The challenge to Drill the depth of the New Offshore Wells

About 80 kilometers from the coast, 1,500 meters below the water surface. The "numbers" of Macondo make an impression: just ten years ago the idea of ​​extracting oil on the high seas, at such high depths, was simply science fiction. And yet, faced with the greatest ecological disaster in the history of the oil industry, there is a comment that recurs with particular frequency among the experts: "BP was not dealing with a difficult well".

Over the course of a few years, the progress of offshore technologies has been so great that it has allowed companies to achieve the limits of the impossible, in front of which Macondo seems almost an amateur exercise. The Deepwater Horizon itself, the platform exploded on April 20, had just broken the submarine drilling record, identifying - again on behalf of BP and always in the Gulf of Mexico - the Tiber field, 10.6 km above sea level, of which over 9 under the backdrop.

There were 33 other offshore installations engaged in exploring the seabed at depths equal to or greater than those of Macondo in the United States. After the Macondo incident, the White House ordered that everyone stay for six months, waiting. of a crackdown on security conditions. The overall number of drills in the Gulf of Mexico, however, is much higher: according to the statistics of Rigzone, in April there were 243, of which about half were in use (in the world they were 578). As for the number of wells, the bottoms in front of Texas and Louisiana are literally studded with holes: it is estimated that there are about 3,500, dug with increasing frenzy as the search for crude oil on the mainland became more difficult, due to the decline of the most "at hand" fields and the spread of so-called resource nationalism. Technology has made it possible to make a virtue of necessity, with progress that in recent years has undergone a truly dizzying acceleration.

Oil was searched for the first time in water in 1938, at a depth of just 4 meters, with a few swimming strokes from Louisiana. The first really "offshore" well, 17 km off the same state, dates back to 1947: the platform was no bigger than a tennis court (the Deepwater Horizon had the size of a couple of football fields) and the crude was transported to land with barges taken by the Navy at the end of the Second World War.

It had to wait until the 1980s before Royal Dutch Shell managed to break the 1,000 foot deep (304.8 meter) threshold and up to 2000 to get to Macondo's 1.5 kilometer, with the Hoover Diana made by Saipem for ExxonMobil. Perdido - inaugurated last March 31 by Shell and capable of producing up to 100 thousand barrels of crude oil and 50 thousand cubic meters of gas per day - sinks its drills into the water for 3 km, more or less like five stacked Empire State Buildings.

But the real breakthrough in the offense is not only linked to the creation of increasingly powerful and sophisticated platforms, but to the new technologies for detecting the deposits, which allow to probe the depths, reconstructing images with three or even four dimensions of the potential deposits of hydrocarbons. This is how great discoveries have been made like that of Tupi, off the coast of Brazil, or Jubilee in the waters of Ghana. Discoveries that represent the future of oil. 

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Fire and Explosion Risk in Oil Gas Drilling

There is always a risk of blowout when perforating a well, with a gas or vapour cloud release, followed by explosion and fire. Additional potential for fire and explosion exists in gas process operations.

Offshore platform and drilling rig workers should be carefully evaluated after having a thorough physical examination. The selection of offshore crew members with a history or evidence of pulmonary, cardiovascular or neurological diseases, epilepsy, diabetes, psychological disturbances and drug or alcohol addiction requires careful consideration. Because workers will be expected to use respiratory protection equipment and, in particular, those trained and equipped to fight fires, they must be physically and mentally evaluated for capability of carrying out these tasks. The medical examination should include psychological evaluation reflective of the particular job requirements.

Emergency medical services on offshore drilling rigs and production platforms should include provisions for a small dispensary or clinic, staffed by a qualified medical practitioner on board at all times. The type of medical service provided will be determined by the availability, distance and quality of the available onshore services. Evacuation may be by ship or helicopter, or a physician may travel to the platform or provide medical advice by radio to the onboard practitioner, when needed. A medical ship may be stationed where a number of large platforms operate in a small area, such as the North Sea, to be more readily available and quickly provide service to a sick or injured worker.

Persons not actually working on drilling rigs or platforms should also be given pre-employment and periodic medical examinations, particularly if they are employed to work in abnormal climates or under harsh conditions. These examinations should take into consideration the particular physical and psychological demands of the job.

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TRAVELLING BLOCK Drilling Rig

The set of sheaves that move up and down in the derrick. The wire rope threaded through them is threaded (or "reeved") back to the stationary crown blocks located on the top of the derrick. This pulley system gives great mechanical advantage to the action of the wire rope drilling line, enabling heavy loads (drillstring, casing and liners) to be lifted out of or lowered into the wellbore. A traveling block is a multisheave pulley used to raise or lower the drill string and casings into a well bore. 

The blocks typically consist of four to six individual sheaves over which the steel cables used to suspend the traveling black are passed. The cables are then attached to the

fixed crown block at the top of the derrick, leaving the lower block free to move up and down the cable fall. A shock absorber and crane hook are attached to the bottom of the traveling block and are used to suspend the drill string. These block assemblies are most frequently encountered in the oil drilling applications and are often capable of handling loads in excess of 1,000,000 pounds (454,000 kg).

Pulley of Travelling Block

Lowering, lifting, and controlling the drill string in deep well bores generally requires an extraordinarily robust hoist arrangement. These hoists usually consist of a crown block mounted in a fixed position at the top of the well derrick and a traveling block at the bottom of the fall of rope. The travelling block sheaves are flat disks with a deep groove machined around their circumference. When grouped together, as they are in the traveling block, they are collectively referred to as a pulley.

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Drill Well with Cable Tool Method

Cable Tool Drilling Bit

Cable tool method has its beginnings 4000 years ago in China. it was the earliest drilling method and has been in continuous use for about 4000 years. The Chinese used tools constructed of bamboo and well depths of 3000 ft are recorded. However, wells of these depth often took generations to complete.

Cable tool rigs are sometimes called pounders, percussion, spudder or walking beam rigs. They operate repeatedly lifting and dropping a heavy string of drilling tools into the boreholes. The drill bits breaks or crushes consolidate rock into small fragments. When drilling in unconsolidated formations, the bit primarily loosens material.

Water, either from the formation or added by the driller, mixes the crushed or loosened into a slurry at the bottom of the borehole. An experienced cable tool driller feels when the accumulated slurry has reached the point where it is reducing bi penetration to an unacceptably slow level. At this point the slurry is removed from the borehole by a bailer. Once the slurry is removed, the bit is reinserted into the hole and drilling continues.

Cable Tool Drilling Rig

Often a cable-tool rig drills only one-tenth as fast as a rotary rig in comparable formations. However, the cost of a cable-tool rig is substantially less than a rotary rig. This tends to compensate for its slower drilling rate. A distinct disadvantage of the cable-tool method is that when high-pressure oil and gas formations are encountered, there is no fluid in the hole to control them. The result is frequent blowouts. 

When a blowout occurs, the oil and gas from the subsurface formation rush to the surface and flow uncontrolled. A blowout may spray the oil and gas several hundred feet into the air, and there is always great danger of a fire. Because of its slow penetration rate and the hazard of blowouts, the cable-tool method is seldom used on wells deeper than (3000 ft or 900 meters). Even on shallower wells, this method has largely been replaced by the rotary method.

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RIG POWER SYSTEM

Most rig power is consumed by hoisting and fluid circulating systems. The other rig systems have much smaller power requirements. Fortunately, the hoisting and circulating systems generally are not used simultaneously, so that the same engines perform both functions.

Total power requirements for most rigs are from 1000 to 3000 hp provided by one or more engines depending on well depth and rig design. Power requirements vary for different drilling jobs, shallow or moderate depth drilling rigs need 500 - 1,000 HP, heavy-duty rigs for 20,000 foot (6000 meters) holes usually need 3,000 hp, Auxiliary power requirements for lighting, etc., may be 100 - 500 hp.

The early drilling rigs were powered primarily by steam. However, because of high fuel consumption and lack of portability of the large boiler plants required, steam-powered rigs have become impractical. 

Modern rigs are powered by internal-combustion diesel (or gas) engines .engines and sub-classified depending on the method used to transmit power to the various rig systems as:

1-Diesel electric type.

2-Direct drive type.

Diesel electric rigs are those in which the main rig engines are used to generate electricity. Electric power is transmitted easily to the various rig systems(the diesel engines generate and deliver electric power by cables to electrical then to electric motors attached to the involved equipments) switch gear then to , where the required work is accomplished through use of electric motors. Direct-current motors can be wired to give a wide range of speed-torque characteristics.

That are extremely well-suited for the hoisting and circulating operations. The rig components can be packaged as portable units that can be connected with plug-in electric cable connectors. There is considerable flexibility of equipment placement, allowing better space utilization and weight distribution. In addition, electric power allows the use of relatively simple and flexible control system. The driller can apply power smoothly to various rig components, thus minimizing shock and vibration problems.

Direct drive rigs accomplish power transmission from the internal-combustion engines using system of pulleys, gears, chains, belts, and clutches rather than generators and motors. The initial cost of a direct-drive power system generally is considerably less than that of a comparable diesel-electric power system. The development of hydraulic drive has improved greatly the performance of this type of power system. Hydraulic drives reduce shock and vibrational problems of the direct drive power system. Torque convertors, which are hydraulic drives designed so that the output torque increases rapidly with output load, are now used to extend the speed-torque characteristics of the internal-combustion engine over greater ranges that are better suited to drilling applications. The use of torque convertors also allows selection of engines based on running conditions rather than starting conditions. Power-system performance characteristics generally are stated in terms of output horsepower, torque and fuel consumption for various engine speeds.

3000hp =2237099.615 watt equal to the power operates 22371 house lamps.

The power on modern rigs is most commonly generated by diesel-electric power units. The power produced is AC current which is then converted to DC current by the use of SCR (Silicon Controlled Rectifier).

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Cellar Purpose in Oil Gas Drilling Onshore

Before We talk about what is Cellar or Cellar purpose, I will mention from rig located in new well location.

Once the site has been selected, scientists survey the area to determine its boundaries, and conduct environmental impact studies if necessary. The oil company may need lease agreements, titles and right-of way accesses before drilling the land. For off-shore sites, legal jurisdiction must be determined.

After the legal issues are settled, the crew goes about preparing the land:

The land must be cleared and leveled, and access roads may be built.

Because water is used in drilling, there must be a source of water nearby. If there is no natural source, the crew drills a water well.

The crew digs a reserve pit, which is used to dispose of rock cuttings and drilling mud during the drilling process, and lines it with plastic to protect the environment. If the site is an ecologically sensitive area, such as a marsh or wilderness, then the cuttings and mud must be disposed of offsite -- trucked away instead of placed in a pit.

Once the land has been prepared, the crew digs several holes to make way for the rig and the main hole. A rectangular pit called a CELLAR is dug around the location of the actual drilling hole. The CELLAR provides a work space around the hole for the workers and drilling accessories. The crew then begins drilling the main hole, often with a small drill truck rather than the main rig. The first part of the hole is larger and shallower than the main portion, and is lined with a large-diameter conductor pipe. The crew digs additional holes off to the side to temporarily store equipment -- when these holes are finished, the rig equipment can be brought in and set up.

Depending upon the remoteness of the drill site and its access, it may be necessary to bring in equipment by truck, helicopter or barge. Some rigs are built on ships or barges for work on inland water where there is no foundation to support a rig (as in marshes or lakes).

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General Step and Procedure Oil Gas Drilling in Onshore

To find oil, you cannot simply punch a hole in the ground. Perhaps, this is what many people believe.

There are many complexities involving multiple service companies and two complete teams of crews. With so much happening (and with so many difficulties regarding scheduling, safety, and environmental practices) drilling for oil is not for the faint of heart.

This is a general 51 steps for drilling in the USA, for example. 

The following steps are necessary in order to produce oil or gas from a well:

1. 10-30 different service companies are required.
2. Each company working on a well must adhere to around-the-clock scheduling, safety and environmental practices.
3. Build a new road to access the rig location.
4. Clear the area for the new rig.
5. Build infrastructure for water and electricity around the rig site.
6. Dig an earthen pit to prevent soil or water table contamination.
7. Dig a pilot hole at the precise location marked by the survey crew.
8. Dig two other holes (the “mouse” hole and the “rat” hole) nearby to hold pieces of equipment and pipe during drilling.
9. A rig that can dig a 10,000 ft. well requires 50-75 people and 35-45 semi-trucks to move and assemble the rig.
10. Assembly of the rig takes around 3 and a half days.
11. A strict inspection of the rig must take place once built.
12. Operations of the rig go on 24/7, typically ceasing only one day each year for Christmas.
13. Two shifts of two complete crews must work the rig every day.
14. There are two stages of drilling: 1. running and cementing of cases and 2. drilling until the bit reaches the depth of the targeted zone.
15. Each drill bit typically lasts 4,500 – 6,500 feet of drilling.
16. Replacing the bit requires the removal of the entire string of drill pipe in a process called “tripping out”.
17. “Tripping out” takes several hours and requires crews to cool the bit and keep the soil and hole intact.
18. To help keep cuttings from plugging the hole, the mud must be sent through shakers to send the cuttings into a separated area.
19. Additional mug system equipment: de-sanders, de-silters and de-gassers, remove smaller particles and gas from the mud.
20. Clean mud is then recirculated back down into the hole.
21. The Blow-Out Preventer (or “BOP”) is installed on top of the casing head before drilling takes place.
22. The BOP must have high-pressure safetly valves designed to seal off the well and block any escaping gases or liquids from the hole beneath in order to prevent a blow-out from occuring.
23. Drilling must begin with a designated surface depth, usually around 50-100 feet below the water table.
24. Special care must be taken to prevent contamination of the water in the water table while drilling by isolating the water table and the wall with concrete and steel encasing.
25. New sections of pipe must be added to the string as the bit drills deeper.
26. When the hole reaches a designated depth, the derrickhands secrete fluid through the hole to condition it for logging.
27. A “logging tool” measures the depth and condition of the hole for the oil company.
28. The tool gives the information of whether or not the well can indeed produce oil or gas.
29. At this point, it must be determined whether the well is to be complete or plugged and abandoned.
30. If the well is designated as a producer, the crew must re-insert the pipe back into the hole to ensure the hole is still intact.
31. To test the hole, mud must be re-circulated.
32. Once everything tests positively, the drill pipe is removed.
33. At this point, the crew must insert the last string of production casing running the entire depth of the hole.
34. Then, the casing is cemented in the hole.
35. The production crew then brings in the work-over unit and rigs it up to prepare the hole for production.
36. The crew runs small diameter tubing into the hole as a conduit for oil or gas to flow through and up the well.
37. Next, the work over unit trips out of the hole and picks up a perforating gun.
38. The perforating gun is lowered into the hole to production depth using a thin metal cable called a “wireline”.
39. An electrical signal is sent down the wireline, firing the gun and igniting explosive charges.
40. These charges create holes through the cement encasing and formation connecting the well bore to the reservoir.
41. To stimulate the flow of hydrocarbons (or oil), sometimes it’s necessary to “frack” the well.
42. “Fracking” involves pumping air, sand and fluids under extreme pressure down the hole and out through the perforations.
43. This fractures or forces cracks into the formation.
44. The remaining particles will hold the cracks open, releasing the flow of oil or gas.
45. Monitoring the flow allows the crew to determine the best location for the “choke”.
46. The “choke” controls the flow of the oil or gas.
47. Once pressure is released, the hydrocarbons are allowed the escape through the fractured zone and flow into the well bore.
48. The oil or gas can now travel up the well casing string.
49. The well bore is isolated from the surrounding formations with casing and cement, preventing any contamination.
50. The final step is to install a pump jack or production well-head, or what’s called the “Christmas Tree”.
51. It’s the time to produce the well and plan for any future field development.

Watch the Video : 

Read More → General Step and Procedure Oil Gas Drilling in Onshore

Preperation Drilling Operation

In the baseline system, all of the equipment necessary for the drilling operation is organized around the derrick, or mast. This is a steel tower , ranging from 50' to 180' in height, which supports the drill pipe with the bit and all the other downhole equipment, and which provides a platform for much of the other equipment necessary to drill the hole. 

Every rig, except for the smallest ones, has a floor just above ground level where most activity required to operate the rig takes place. The driller, who has minute-by-minute control of the rig's operation, has a console here and most pipe handling (adding a new piece of pipe, making and breaking drill string connections, changing bits, etc.) takes place on the floor. In smaller rigs, the mast and the floor are a unit and are simply raised into position in preparation for drilling. 

Bigger rigs, which may require 50 to 60 large truck loads for transportation, are usually assembled at the drill site, a job which may take s e v d days, even in accessible locations on land. offshore, or in locations with difficult access, this assembly is much more complex and time-consuming. Eventually the mast will be erected, the power generation system on-line, the fluidhandling equipment plumbed together, and the myriad other smaller components in place; only then is the rig ready to begin drilling a hole 

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Solids Control Innovations To North American Shale Fields

While the last year has seen a ramping up of onshore drilling in shale fields across North America, it’s clear that “caution” still remains the watchword when it comes to drilling and production budgets.

Anadarko, ConocoPhillips and Hess already have announced reductions in 2017 E&P budgets, and in the words of Anadarko CEO R.A. Walker, “We sincerely believe the volatility of the current operating market requires financial discipline.”

Such volatility and the focus from shale operators and drilling contractors on financial discipline, reduced costs and increased efficiencies is shining the spotlight on a key sector of the drilling market—solids control.

Drilling fluids play a crucial role in drilling activity in shale fields, cooling and lubricating drillbits, carrying drill cuttings to the surface, controlling pressure at the bottom of the well and ensuring that the formation retains the properties defined for that well.

The effectiveness of such fluids is highly dependent on solids control and the ability to separate the mud from rock particles and low-gravity solids so that clean mud is recycled and circulated back into the drilling system. If there are too many solids in the mud, ROP is reduced, and torque, drag and abrasion are increased as well as potential lost circulation and production.

The more capable the drilling rigs and the better the solids control technologies, the greater the drilling efficiencies and levels of potential production.

Current technology limitations

Shale shakers separate drill cuttings by passing the muds through a shale screen with separation achieved by vibrations and high G-forces. But there are limitations to these devices.

First, there is the capex and opex required for the shale shakers—not a one-off cost but a drag on finances throughout operations due to the need for the shale screens to be continually replaced.

There also is more onsite equipment, personnel, and greater costs and HSE risk.

Also, there are the inefficiencies of the shale shaker-based process itself.

The drilled solids are often broken down into fine particles that are difficult to remove, leading to an increase in solids in the drilling fluid, a decline in drilling fluid efficiency and a negative impact on penetration rates and equivalent circulating density.

Another downside of vibrating-type shale shakers is higher volumes of mud being lost and more drilling waste generated. One industry guru working for a major operator once said that 15% of all the mud used per well is lost in some form or another via the shakers.

Viable alternative

It’s with these issues in mind that Cubility’s filter beltbased MudCube technology is proving an effective alternative to shale shakers in shale fields.

The MudCube is an enclosed vacuum-based system that eliminates the traditional process of shaking fl uid and solids. Instead, drilling fl uids are vacuumed through a rotating filter belt that uses high airfl ow to separate the cuttings from the fl uid.

The cleaned drilling fl uids are then returned to the active mud system, and the drilled solids are carried forward on the filter belt for disposal. As opposed to shakers, the MudCube processes 100% of the mud, immediately increasing performance.

The system also eliminates the need for multiple shaker panels, with the solids removal efficiency also ensuring that as much as 80% more mud is recovered than competing technologies, which is a huge benefit when multiplied by several onshore rigs.

The improved separation capabilities of the MudCube also lead to better quality drilling fluid, more drilling fluid recycled back to the mud tanks to be reused for drilling, less waste and improved drilling efficiencies with stable drilling fl uid properties and a decrease in nonproductive time.

There are also the financial benefits of avoiding screen replacements on a regular basis—filter belts need replacing but not at such fast rates.

In addition, the MudCube is a much more compact alternative to shale shakers. A typical three-deck shaker weighs about 3 metric tons compared to 1 ton for the MudCube.

Deployments across North America

The MudCube’s easy installation on drilling pads is ensuring that it can impact the bottom line almost immediately.

In 2016 Cubility partnered with EQT Corp., and the MudCubes were successfully deployed to an onshore fl uid rig that was drilling Marcellus wells in western Pennsylvania. Cuttings were easily lifted out of the wellbore, leading to immediately improved solids control and waste disposal.

The MudCube also has been successfully deployed for Murphy Oil in Canada, and the company is evaluating the service for possible use in the Eagle Ford Shale as well.

New Tech Solids Inc. and the MudCube delivered dry cuttings with Murphy Oil in Canada. (Source: Cubility)

Mending the broken value chain

Cubility also is looking to contractor partnerships and offering the MudCube as a rentable system to enable contractors to embrace the latest solids control innovations and address the broken value chain where operators drive down day rates, leaving contractors with little scope for new equipment.

To this end Cubility is partnering with Houston-based Stage 3 Separation in providing a modular, easy and inexpensive installation and operation of MudCube, a system specifically designed for onshore shale operations and that can be up and running in a matter of days as an integrated part of the rig design.

It’s through exclusive distribution partnerships such as this and also with Canadian-based New Tech Solids Inc. (a recent deployment is taking place with Shell via New Tech Solids) that the next few years is likely to see more and more MudCubes deployed across North American shale fields through these service providers.

In today’s tight but ultrafast land drilling market, any solids control solution must provide immediate “wins” in terms of reduced costs and increased efficiencies. Vacuum and filter belt-based enclosed solid control systems are achieving this. 

Read More → Solids Control Innovations To North American Shale Fields

Rig Service

A service facility is a piece of material that is used for the maintenance of wells such as oil and gas wells. Service facilities are not intended for drilling, but for completing other tasks related to oil and gas wells. Some well-maintained wells maintain their own service facilities, while others prefer to rent them because they can be very expensive. Specialists performed service facilities when they are needed for routine maintenance and emergencies.

Once a well is perforated and productive, it requires periodic maintenance. This is where a service facility enters. When components have to be replaced or a well has to be cleaned, it is done with a service facility. Likewise, when a well is to be closed for any reason, the crew uses a service facility to complete the tasks associated with shutting down the good and fixing it for safety.

Service facilities are loaded on large vehicles that carry them to the site well. The drilling rig is in itself a telescopic tower fixed with tie rods, which keep it in place. Attachments can be mounted on the rig service to complete various tasks related to the activities of the wells. In special circumstances, attachments may be added to a service facility so that it may puncture.

Also known as completions of installations, workover systems, or traction units, service facilities are managed by a crew of people. The crew members gather the rig, confirm it is safe and it works properly, and complete the task assigned to the good. It is necessary to have more people, both for security and why some activities can not be completed by a single person. People who are just beginning are known as thugs and work their way into more advanced positions as tool dealers.

Working on a service desk can be dangerous. The equipment is large and heavy, and when it is not installed and maintained properly, it may pose a safety risk. People are also at risk of electric shock when working with good maintenance equipment and may be endangered by environmental toxins that may be present around oil and gas wells. In recognition of the dangers, oil and gas occupations can come with very high salaries along with the benefits. Employers usually have to pay high civil liability and disability insurance because workers' claims are much more likely than other trades.

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What is Petroleum Well or Oil Well ?

An oil well is a perforated tree through a portion of the eartha crust in order to recover crude petroleum products. From the concept of good to its abandonment, it undergoes several stages of development. Oil wells can be run in a variety of positions and not all produce the same product. They will always produce at least a small amount of natural gas, which may or may not be caught for sale.

The first registered oil well was built in 347 CE in China and technology had spread to Japan since the seventh century. These simple drilling constructions, made of bamboo, have been replaced as technology and processes have been refined. The modern age has brought perforated petroleum wells with a rigid cable and then rotary drills. Modern drilling techniques allow nearly horizontal drilling, providing access to hydrocarbon reserves that are deep in the subsoil.

Perforation starts once a suitable site has been selected and all plans have been finalized. A hole between 5 and 50 inches (12.7-91.4 cm) was exerted. This section is the wider segment of the hole, as each subsequent perforated segment will be slightly smaller so as to reduce the pressure originating from the bottom. After each section is perforated, a casing made of steel is placed inside the hole and cemented in place. There are usually no more than five successive segments practiced in any hole.

The oil well must be completed, ie it must be adapted for oil production and harvesting. Often the pressure accumulated within the reserve is sufficient to force the oil on its own strong, but if the pressure level is insufficient, a pump is installed in place. The oil is then harvested by a series of valves known as production trees set top installation. These keep track of the oil pressure inside the well and adjust accordingly. Eventually, the installation will be abandoned when it is no longer profitable to operate.

A petroleum well can produce mainly petroleum or gas and can produce both. Small amounts of natural gas, which is a byproduct of the oil creation itself, are present in every oil well. Some wells produce almost entirely gas.

Oil wells can be placed either onshore or offshore. The function of the good is the same regardless of the position, but due to the difficulty of drilling and maintaining a well in the sea, offshore wells are much more expensive. These wells are punched only when the presence of a large amount of oil has been proven. They also require more planning and have more security requirements.

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CONVENTIONAL OIL

Definition Oil is a hydrocarbon formed over thousands of years from the decomposition of dead plants and organisms. Intense heat and pressure on this material triggers a reaction, which leads to the creation of oil

Conventional oil is a term used to describe oil that can be produced (extracted from the ground) using traditional drilling methods.  It is liquid at atmospheric temperature and pressure conditions, and therefore flows without additional stimulation.  This is opposed to unconventional oil, which requires advanced production methods due to its geologic formations and/or is heavy and does not flow on its own. 

You may have heard of these terms used to distinguish different types of oil:

​Light vs. Heavy - this refers to the density of oil and its ability to flow.  Lighter oil can be refined with minimal processing due to higher fractions of light hydrocarbons.

Sweet vs. Sour - this refers to the sulphur content of the oil, sulphur must be removed prior to refining.  When oil has sulphur greater than 0.5% it is referred to as "sour."

Because of these variations, oil quality is a spectrum and the distinction between conventional and unconventional is not always black and white. Generally, however, if traditional drilling techniques are used in the oil production it is considered conventional regardless of its physical properties.

Conventional oil is produced using drilling technologies that utilize the natural pressure of an underground reservoir.  Production of a conventional oil well has four main phases[2]:

Exploration: Geological exploration is a series of technologies that are used by geologists and geophysicists to predict the location and extent of underground oil reservoirs.

Drilling: Once a reservoir has been located with sufficient certainty, a drilling rig is used to bore a hole from the surface to the oil reservoir.  Piping is then inserted, allowing the oil to be brought to the surface.  Some of the oil in the reservoir will be produced using the natural pressure of the reservoir.  

Pumping: Gradually the pressure of the well will decrease as oil is produced. At this point a pump will be connected to allow the remaining oil to be extracted.

Abandoning: After all the economically viable oil has been extracted from the well, the well is filled with cement to prevent any hydrocarbons from escaping and a special cap is placed over it to protect the area[3].

Context

Conventional oil tends to be less expensive and complex to extract than unconventional oil due to the routine nature of the production techniques.  This oil is also the most valuable in global markets because it requires the smallest amount of processing prior to refining to create value-added products. Consequently, many of our global conventional oil supplies have already been extracted, limiting the availability of these source for future extraction[2].

Generally, drilling and well abandonment are well-understood and regulated processes but there are always risks with such industrial operations. In drilling, pressure must be regulated carefully to avoid accidents and immediate environmental impacts like land disturbance must be carefully monitored.  After abandonment, well leaks can occur if improper procedures were taken.  

As with all fossil fuel production, there are also concerns with greenhouse gas emissions from their combustion 

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Steerable Downhole Mud Motor - Directional Drilling

Steerable Downhole Mud Motor (SDMM) commonly referred to as Mud Motor or Drilling Motor acts much as a positive displacement motor which provides additional rpm to the drill bit from the flow of drilling fluid (mud).

This drilling motor is far different from an electrical motor in it's working principle and operation.

(A lot of people get confused initially)

Since its introduction, the positive displacement motor has undergone revolutionary changes and improvements. Downhole drilling motors have proven to be successful in the most rigorous of drilling environments. From the time of its inceptions, the mud motors have gone extensive improvements that has enhanced its performance, operational and economical reliability. 

Today there are numerous players in the industry providing mud motors for different operational requirements. Few to name are National Oil Varco (NOV), Schlumberger, Halliburton, Baker Hughes, Weatherford, Cavo, Bico, Jaguar, APS, etc. Different mud motors provided by different companies vary a little from each other but, there basic operating principle remains the same. 

Mud Motors have extensively wide range of applications and few of them are listed below:

Conventional Directional Drilling

Side-Tracking

Performance Drilling

Short/Medium/Ultra-short Radius Wells

Air/Foam or Under-balanced Drilling 

ERD Wells

HP/HT Wells

Coiled Tubing Drilling

Vertical Drilling

Casing Drilling

Milling

Coring

Slim Hole Drilling

Working Principle

Mud motors converts the flow energy of drilling fluid (mud) in rotational motion that's utilized in rotating drill bits at a much higher rpm. 

It's imperative that flow rate can be used to control the rpm of the drill bit as per operational requirements. Flow rates for muds are provided by the mud pumps.

Bit RPM = {Flow rate (in GPM) x RPG (Revolutions Per Gallon)} + Rotary RPM 

Note: 

RPG is defined as the revolutions made by bit box and in turn bit, when one gallon of mud flows through it & is mentioned by the manufacturer for each type of SDMM.

While sliding rotary rpm will be zero.

Parts of SDMM:

Simple classification of SDMM parts can be categorized as: 

Top Sub Options

Power Section

Drive Shaft Assembly

Adjustable Bent Housing Assembly

Bearing Assembly

Bit Box

Top Sub options

Top Sub: 

Top sub is simply a cross over housing at the top end of the motor. The lower connection uses a thread that connects to the upper box of the stator housing.

Dump Sub:

It contains a Dump Valve Assembly. This allows the mud to fill or drain from the drill string while tripping.

To avoid the ingress of solids from the annulus when the pumps are off, it’s normal to run a float sub as close to the motor as possible.

The motor will function perfectly without a dump valve - It can be laid down and replaced by a sub having the same connections or run with the ports blanked-off. 

Failure of the dump valve assembly can cause sometimes serious troubles.

Motor Catch & Rotor Catch Top Subs:

The rotor catch system is designed to retrieve the motor in case of a housing fracture. It will retrieve the motor from the upper stator box connection down to the drill bit. The motor catch system has the additional feature of an integral catch flange within the top sub. It will retrieve the motor from the top sub down to the drill bit.

Power Section

Positive Displacement Motors (commonly called a PDM) are reverse applications of a Moineau pump or screw pump. 

It mainly consists of Rotor & Stator.  

Rotor is chrome-plated alloy steel of spiral-helix shape. 

Stator is a hollow steel housing, lined with a molded-in-place elastomer rubber compound. 

A spiral-shaped cavity is produced in the stator during manufacturing. The rotor is produced with matching lobe profile and similar helical pitch to the stator, but with one lobe less. The rotor can therefore be matched to and inserted inside the stator. When assembled, the rotor and stator form a continuous seal along their matching contact points. Fluid is pumped into the motor’s progressive cavities. The force of the fluid movement causes the shaft to rotate within the stator. Thus, it is a positive displacement motor. The rotational force is then transmitted through the connecting rod and drive shaft to the bit.

  

Stage is the distance measured parallel to the axis between two corresponding points of the same spiral lobe. This distance is commonly referred to as the lead of the stator. A slight interference fit between rotor OD and stator ID controls motor power. 

Mud motors are divided into slow-speed, medium-speed and high-speed types. This is done by changing the pitch of the motor stages, by the number of "lobes" and resultant cavities of the stator. 

The greater the number of lobes, the higher the motor torque and the lower the output RPM. 

Increasing the flow rate through a given power section directly increases the output speed. To increase the output speed of a power section without changing the flow rate, the cavity size is changed. A high speed power section will require a larger fluid inlet area (cavity) to allow more fluid throughput into the cavity.

The torque generated by the power section is proportional to the differential pressure applied across the power section and is independent of fluid flow. Generally, the more weight applied to the bit, the higher the torque needed to keep the bit turning, so the higher the differential pressure across the Power Section.

The maximum recommended differential pressure is limited by the stator elastomer. If pressure increases beyond the limits of the elastomer, the stator elastomer will deform, breaking the cavity seal so the mud flow leaks past the rotor and rotation stops – this is commonly known as a stalled motor.

Drive Shaft Assembly

The drive shaft assembly converts the eccentric motion of the rotor into concentric rotation for the bearing assembly via a connecting rod attached to the lower end of the rotor. It transmits the torque and rotational speed from the rotor to the drive shaft and bit. Universal joints convert the eccentric motion of the rotor into concentric motion at the drive shaft. 

It also accommodates any angle set on the adjustable bent housing (or fixed bend housing) and carries the thrust load from the rotor caused by the pressure drop across the power section.

Adjustable Bent Housing

ABH connects stator to the bearing assembly and also houses drive shaft assembly. It has a field adjustable angle-setting to produce a wide range of build rates.

Angle setting may be set to zero for vertical drilling or may be set to any other angle setting as desired. Once the angle is set for the mud motor, it can't be changed when it's down hole and has to be pulled out of the hole to change the angle-setting.

Higher rotary rpm could be used at low angle-setting as compared to a high angle-setting.

Drilling at a higher rotary rpm provides a drill bit with more torsional force provided by the entire rotating drill string as compared to the torsional force provided alone by the mud motor.

(That's the reason why ROP in rotary mode > ROP in sliding mode)

Bearing Assembly

The drive shaft assembly is supported within the bearing housing by radial and axial thrust bearings. It transmits the rotation of the drive shaft assembly to the drill bit and the compressive thrust load created by the weight of the collars and drill string to the rotating bit box & supports the radial and bending loads developed while directional drilling.  

It also carries the tensile off-bottom thrust load produced by the pressure drops across the rotor and the drill bit, as well as any load caused during back reaming. The high capacity radial bearings readily withstand side loads caused by drilling with a deflection device or uneven cutting action along the drill bit periphery. The tungsten carbide radial bearings and angular contact bearing section supports the radial loads along the full length of the bearing assembly, creating a very stiff, strong assembly

Types of Bearing Assembly-

Mud Lubricated Bearing Assembly

Oil Sealed Bearing Assembly

Mud Lubricated Bearing Assembly regulate the flow of mud through the bearing assembly. This diverted mud (usually 4 - 10%) is used to cool and lubricate the shaft, radial and thrust bearings. It exits to the annulus directly above the bit sub. The exact percentage of mud diverted is determined by the condition of the bearings and the pressure drop across the bit. Mud lubricated bearing assemblies can be used in the hottest holes with the lowest aniline point drilling fluids, as there are no elastomeric seals.

Oil Sealed Bearing Assembly is an alternative to the mud-lubricated bearing. A sealed bearing would be recommended where corrosive muds are used, where a lot of LCM of various sizes is pumped or where there is a requirement for a very low pressure drop across the bit (Pbit).

Bit Sub

At Bit sub the drill bit is make up with the motor and it's the only moving external part of the motor.

  

Note: 

In addition to above, different manufacturers can have more or less parts.

The operating conditions and parameters for the mud motors may vary for different manufacturers.

Read More → Steerable Downhole Mud Motor - Directional Drilling

Oil Exploration

Crude oil is usually located deep below the earth's surface, without any visible traces of being present.

In the early years of the oil industry, one could easily find small amounts of oil in the vicinity of the oil urinating drilling. "Oil Lakes" are small amounts of oil that come up on the surface or in water.

However, a well drilling is very expensive; Therefore, alternative methods have been sought in order to locate oil. Today, geologists determined using a range of techniques where oil could be found. They make use of include seismic and visual observation techniques to determine the geological formations could contain oil.

• Seismic surveys

this case a small amount of underground explosive is detonated. In addition, to be sensitive instruments used which register the shock waves moving across the ground and which are reflected by rock walls. On the basis of the speed and direction of the waves geologists can identify the type of rock formations, and to detect the types of which are known to oil or hydrocarbons (such as gas) may contain.

• Vibro-seismic survey

, with special vibrating trucks are used, which is a controlled signal to submit the bottom. Although this method is more complicated, it is often used in places where explosives can not be used for practical reasons.

• Geophysical research

, this method is used to measure the thickness of sediment and in order to map out the shape of the structures within the sediment. In this way, often underground structures could be located in the last 30 years where oil had gathered.

• Research based on aerial photographs

on the basis of aerial photos, maps can be established in which the main geological properties are shown of an area. The photos are also used to determine oil field pipelines and infrastructure very closely. This information is of great value for planning seismic surveys and other projects.

• Surface Research

Here, specific localized areas on the ground and it is determined their height. One of the tools used therewith, is a theodolite, which is equipped with a telescope that measurement angles horizontally and vertically.

• Gravity investigation

In this method, there is used a highly sensitive gravimeter, which is analyzed to gravity variations. These variations may indeed indicate hidden geological structures. The study is usually performed in an early stage of exploration. The researchers thereby identify areas that may be potentially interesting. At these zones is then carried out, a more detailed seismic survey.

Drilling for oil

When certain areas of potential interest are labeled, are drills used to dig wells. Seismic research shows that the best places to look for oil. In this way, the risk of finding dry wells ( "dry hole") is limited. They contain no oil.

A drill is guided straight into the ground. If the rig can not be drawn directly on the surface, it is placed next to it and is drilled at an angle. The horizontal drilling technology is used to drill into the portion of the source which horizontally through the oil (the "output section") passes along the path from the oil reservoir.

Oil Transport

Crude oil is transported by pipeline from the drilling rig to tank farms. Since the oil is stored in huge tanks. The crude oil is then transported by pipeline to a local refinery or an oil tanker to an overseas refinery.

Read More → Oil Exploration

Work on oil rig

Working on an oil rig? Work on oil rig is possible without a degree. Offshore companies offer excellent career opportunities. Any employee who works on an oil rig must be in good condition and can yield a high concentration for a long time. Working on an oil rig (offshore work) is different from working on land (onshore).

A working on an oil rig

A working on an oil rig is not a traditional working day of eight hours but usually 12 hours a day 7 days a week. To keep these twelve full hours are (usually) four breaks which can be eaten four times. After 12 hours of hard work is quite 12 hours. It is important to find a good rhythm of work and rest 12 hours to 12 hours in order to stay mentally and physically fit. The advice is to catch sleep at least 8 hours. About how workers on an oil rig rest can be read in the following paragraphs. There is no traditional workweek because we work seven days a week with no days off. The big advantage of working on an oil rig is also working a month are released after a month. Often, this is done on 4 weeks and off in a time period of 4 weeks. In the six months of active work there is "enough" money earned for the whole year. Incidentally, all expenses incurred covered by traveling through the employer. On the working conditions of offshore employers you do not have to worry. These are above average. The workday is long and quite heavy by the conditions of cold winds and very hot days. This cuts there if you have to work in these conditions for a long time. This is a good mental and physical condition required.

Work and rest

After working on the rig you have 12 hours of rest. It is important to sleep well in these 12 hours. Of course relaxation is also an important point. There are therefore affected in almost all oil rigs amenities. You can think of a common space with TV, computer, pool table and the like. The facilities on the rig are generally better hotels. So rigs also have sports facilities. Larger rigs even have a soccer field, basketball court, and the like. This makes working for a long time on an oil rig more pleasant. Important to know is that there is also very little privacy making work and life makes on an oil rig also mental strain. Can someone good with these conditions than working on an oil rig is a lucrative and interesting job with many career opportunities.

Read More → Work on oil rig

Horizontal Well

What is 'Horizontal Well'

A well that is transformed into horizontal in depth, providing access to the oil and gas reserves in a wide range of angles. horizontal wells has grown in popularity during the 1980s, such as natural gas and oil exploration turned away from less productive than vertical wells. This type of well is used to gain access to conventional sources of reserves.

horizontal wells became economically viable in 1980, such as computerized mapping and directional localization and holes made access difficult to reach deposits of oil and natural gas, easier and more convenient. Of the three categories of drilling horizontal rays - short, medium and long - average drilling is more prevalent

horizontal wells tend to be much more productive than vertical wells. This is because they allow a single well to reach more points, without the need for further vertical wells. This makes each far more productive individual, since most tanks are more productive throughout their horizontal axis that their vertical access. horizontal wells also reduce the risk of introducing water or gas intrusions in the case of oil exploration.

While more productive than vertical wells, horizontal wells tend to be more expensive. Although this cost has decreased over the years tends to be a learning curve associated with exploring new types of fields, especially for developers and inexperienced.

horizontal wells usually starting with the drilling of a vertical well. Drilling vertically allows engineers to examine rock fragments at different levels, in order to determine where the reserves are located. horizontal wells are then "kicked off" from the auction primary vertical, and enter the tank to an "entry point" after the drilling of an arched hole.

The extraction of oil and gas from conventional sources, such as shale rock formations, often requires the use of horizontal drilling technologies.

Read More → Horizontal Well

Vertical Well

A well that is not converted into horizontally in depth, allowing access to the oil and gas reserves are located directly below the point of surface access. Historically, natural gas and oil exploration has involved the use of vertical wells because the directional drilling technology was expensive and complicated. Drilling of vertical wells is considered a conventional method.

Vertical shafts differ directional wells, such as horizontal wells, deep because they require the use of directional drilling. This makes them less expensive to develop, although less productive because of their limited range.

While vertical wells may be less complicated to bring in line of directional wells, their limited angles make them less able to reach a wider part of the underground area. Because a vertical shaft can access only the reserves of petroleum and natural gas directly under, making a large manufacturing industry requires the drilling of many vertical wells. They are especially handy in case of reserve thin layers located over a wide area. Since a vertical well can be drilled in a single direction, the exploration company must estimate the most productive portion of the reserve from the beginning; a vertical drilled well can go right through the reserve, drawing only a portion of the available energy.

horizontal wells usually starting with the drilling of a vertical well. Drilling vertically allows engineers to examine rock fragments at different levels, in order to determine where the reserves are located. horizontal wells are then "kicked off" from the primary vertical shaft.

The extraction of oil and gas from unconventional sources such as shale rock, often requires the use of horizontal drilling technologies because the source can be executed in the horizontal direction. If the reserves are located in a residential area, well vertical drilling would require both the displacement of residents or require them to live next to a tower.

Read More → Vertical Well