Natural Gas Production and Processing Operations

There are two types of wells producing natural gas. Wet gas wells produce gas which contains dissolved liquids, and dry gas wells produce gas which cannot be easily liquefied

After natural gas is withdrawn from producing wells, it is sent to gas plants for processing. Gas processing requires a knowledge of how temperature and pressure interact and affect the properties of both fluids and gases. Almost all gas-processing plants handle gases that are mixtures of various hydrocarbon molecules. The purpose of gas processing is to separate these gases into components of similar composition by various processes such as absorption, fractionation and cycling, so they can be transported and used by consumers.

Absorption processes

Absorption involves three processing steps: recovery, removal and separation.

• Recovery.

Removes undesirable residue gases and some methane by absorption from the natural gas. Absorption takes place in a counterflow vessel, where the well gas enters the bottom of the vessel and flows upward through absorption oil, which is flowing downward. The absorption oil is “lean” as it enters the top of the vessel, and “rich” as it leaves the bottom as it has absorbed the desirable hydrocarbons from the gas. The gas leaving the top of the unit is called “residue gas.”

Absorption may also be accomplished by refrigeration. The residue gas is used to pre-cool the inlet gas, which then passes through a gas chiller unit at temperatures from 0 to –40 °C. Lean absorber oil is pumped through an oil chiller, before contacting the cool gas in the absorber unit. Most plants use propane as the refrigerant in the cooler units. Glycol is injected directly into the inlet gas stream to mix with any water in the gas in order to prevent freezing and formation of hydrates. The glycol-water mixture is separated from the hydrocarbon vapour and liquid in the glycol separator, and then reconcentrated by evaporating the water in a regenerator unit.

• Removal

The next step in the absorption process is removal, or demethanization. The remaining methane is removed from the rich oil in ethane recovery plants. This is usually a two-phase process, which first rejects at least one-half of the methane from the rich oil by reducing pressure and increasing temperature. The remaining rich oil usually contains enough ethane and propane to make reabsorption desirable. If not sold, the overhead gas is used as plant fuel or as a pre-saturator, or is recycled to the inlet gas in the main absorber.

• Separation.

The final step in the absorption process, distillation, uses vapours as a medium to strip the desirable hydrocarbons from the rich absorption oil. Wet stills use steam vapours as the stripping medium. In dry stills, hydrocarbon vapours, obtained from partial vaporization of the hot oil pumped through the still reboiler, are used as the stripping medium. The still controls the final boiling point and molecular weight of the lean oil, and the boiling point of the final hydrocarbon product mix.

Other Processes

• Fractionation.

Is the separation of the desirable hydrocarbon mixture from absorption plants, into specific, individual, relatively pure products. Fractionation is possible when the two liquids, called top product and bottom product, have different boiling points. The fractionation process has three parts: a tower to separate products, a reboiler to heat the input and a condenser to remove heat. The tower has an abundance of trays so that a lot of vapour and liquid contact occurs. The reboiler temperature determines the composition of the bottom product.

• Sulphur recovery.

Hydrogen sulphide must be removed from gas before it is shipped for sale. This is accomplished in sulphur recovery plants.

• Gas cycling.

Gas cycling is neither a means of pressure maintenance nor a secondary method of recovery, but is an enhanced recovery method used to increase production of natural gas liquids from “wet gas” reservoirs. After liquids are removed from the “wet gas” in cycling plants, the remaining “dry gas” is returned to the reservoir through injection wells. As the “dry gas” recirculates through the reservoir it absorbs more liquids. The production, processing and re circulation cycles are repeated until all of the recoverable liquids have been removed from the reservoir and only “dry gas” remains.

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Properties of Hydrocarbon Gases - Drilling Knowledge

Flaring Gas Testing

According to the US National Fire Protection Association, flammable (combustible) gases are those which burn in the concentrations of oxygen normally present in air. The burning of flammable gases is similar to that of flammable hydrocarbon liquid vapours, as a specific ignition temperature is needed to initiate the burning reaction and each will burn only within a certain defined range of gas-air mixtures. Flammable liquids have a flashpoint (the temperature (always below the boiling point) at which they emit sufficient vapours for combustion). There is no apparent flashpoint for flammable gases, as they are normally at temperatures above their boiling points, even when liquefied, and are therefore always at temperatures well in excess of their flashpoints.

The US National Fire Protection Association (1976) defines compressed and liquefied gases, as follows:

·     “Compressed gases are those which at all normal atmospheric temperatures inside their containers, exist solely in the gaseous state under pressure.”

·     “Liquefied gases are those which at normal atmospheric temperatures inside their containers, exist partly in the liquid state and partly in the gaseous state, and are under pressure as long as any liquid remains in the container.”

The major factor which determines the pressure inside the vessel is the temperature of the liquid stored. When exposed to the atmosphere, the liquefied gas very rapidly vaporizes, travelling along the ground or water surface unless dispersed into the air by wind or mechanical air movement. At normal atmospheric temperatures, about one-third of the liquid in the container will vaporize.

Flammable gases are further classified as fuel gas and industrial gas. Fuel gases, including natural gas and liquefied petroleum gases (propane and butane), are burned with air to produce heat in ovens, furnaces, water heaters and boilers. Flammable industrial gases, such as acetylene, are used in processing, welding, cutting and heat treating operations.

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Optimizing Artificial Lift Through Enhanced Control Systems

Canada is the world’s fifth largest oil producer. This is due in large part to the country’s vast reserves in and around Alberta, which contains the third-largest known oil reserves in the world.

Calgary-based ARC Resources Ltd. has called this oilrich region home for more than 20 years. The company has assets distributed across western Canada and operations that include E&P and development of conventional oil and natural gas.

Just across Alberta’s western border in northeast British Columbia, ARC Resources is one of the largest operators in the Montney region, which is considered one of the best tight gas plays in North America. And it was here that ARC Resources recently decided to begin optimizing the control systems it was using for its large multiwell natural gas production sites. The existing systems in place at these sites didn’t support artificial lift, which would soon be needed to maintain production levels. The systems also presented both expansion and safety challenges that the company wanted to address.

Operations at a crossroad

ARC Resources already had optimization programs at its smaller pads that contained only one to four wells. Control systems in place at these pads supported the use of artificial lift systems to help maintain or increase production as these wells depleted.

Larger pads of five or more wells, however, lacked control systems to support artificial lift systems. As some of these sites approached production milestones of 10 to 15 years, the company knew that it would need to make improvements in the near future.

“We were very successful with using assisted lift to keep production stable in the smaller fields,” said Charlie Kettner, programming specialist for ARC Resources. “We didn’t have the same optimization option in our bigger pads. So our production engineers wanted to find a control solution that would allow us to bring artificial lift to these fields as well.”

The existing controllers were not capable of handling the large amount of integrated operations required to run the entire well pad. As a result, the company had to use multiple controllers hardwired together along with remote terminal units (RTUs). This approach not only made the control infrastructure more complex and thus more prone to mistakes but also limited the amount of information available for control and monitoring.

The use of multiple hardwired controllers also presented safety challenges. ARC Resources relies on its control architecture to monitor toxic and explosive gases and to take actions such as turning on an exhaust fan or blocking wells as conditions dictate. But the controllers could lock up and freeze their outputs and give no indication that there was a fault. This forced the company to add “watch dog” timer hardware to monitor for such conditions.

A ‘canned package’

Kettner reached out to Rockwell Automation to begin discussions about optimization options that would support artificial lift systems at the large multiwell pads as well as simplify control and address safety concerns.

Their talks led them to the ConnectedProduction well manager system from Rockwell Automation, which includes an out-of-the-box Allen-Bradley ControlLogix programmable automation controller (PAC) and FactoryTalk View human-machine interface that requires no custom coding. The PAC gives ARC Resources single-platform control for large sites with up to 32 artificial lift wells and contextualized production information to help operators maintain optimal production levels and troubleshoot issues.

“It’s a canned package,” Kettner said. “You order it, install it and plug in your data to the points it’s looking for, and away you go.”

Kettner and his team decided to pilot the new technology at an eight-well production site named Sunrise near the town of Dawson Creek, British Columbia, before installing it at four other multiwell pad sites.

One of the benefits they first discovered during this trial run was the add-on instructions included in the ConnectedProduction, which helped them save about two days of programming during the installation process. Because the technology uses an open architecture, integration with other vendor hardware at the site was easy.

Enhanced visibility and safety

ConnectedProduction has eliminated the need for multiple controllers and RTUs that were previously in place at the Sunrise site. Now all well pad controls have been consolidated into a single control platform. In addition to simplifying the architecture, this will help lower hardware and software costs for the site.

The system also enables the use of artificial lift systems, including on/off timers and plunger lift systems, and provides visibility into those systems.

“Operators can track events in the Connected- Production solution to see what stage we’re in of the optimization cycle and make better decisions about what to do next,” Kettner said. “Operators can see, for example, that a timer well is not producing anymore and move to the next step of putting a plunger in the hole.”

The new system also is helping ARC Resources enhance safety by reducing the risk of faults going undetected at the Sunrise site.

“Now if something goes wrong with the processor, or if an I/O [input/output] rack comes undone, the ControlLogix platform can fault to a safe state where it shuts down all the processes,” Kettner said. “It takes all the power off the solenoids and essentially results in an emergency shutdown.”

Another benefit of the ConnectedProduction system is that it can support a flow-measurement card within the control panel. This has allowed Kettner to eliminate the use of a separate flow-measurement computer, which is saving his company tens of thousands of dollars at the site.

“We just plug the card into the rack, and it communicates on the backplane,” Kettner said. “It’s given us huge cost savings.”

Looking ahead, Kettner already has orders in to bring the ConnectedProduction system to at least four more large multiwell pads in the area.

“We’ve seen the value of the Rockwell Automation solution and want to bring it to our other sites where we need assisted lift,” he said. “On new pads we’ll implement this right from day one so it’s there and available when it’s needed. And we can just turn it on.”

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Reduced Tubing Wear with Coupling

The economic landscape of the oil and gas industry has shifted and, as a result, operators in U.S. shale plays are increasingly looking for ways to streamline their practices and boost profitability. Coming to grips with production costs is crucial in the $50/bbl environment, and every component used in production should be scrutinized to assess if changes and improvements can be made to reduce wastage, costs and time lost on the well.

For example, nearly all of the wells operating in U.S. shale fields require artificial lift, and nearly half of those wells experience failure as a result of couplings contacting the inner tube wall, which creates friction that leads to considerable wear and damage. These failures are both hazardous and costly, running into the tens of thousands of dollars per well per year. Across the industry workover costs account for hundreds of millions of dollars per year.

To come up with an efficient, more cost-effective solution for well workovers, Materion Corp. partnered with Hess Corp. to develop and field test stronger, more fatigue-resistant sucker rod couplings made of ToughMet 3 TS95 alloy.

Materion developed a new temper of its ToughMet 3 alloy specifically to address the challenges of coupling on tubing wear. This copper-nickel-tin spinodal alloy was originally engineered by Materion for use in drilling equipment. Offering high strength and low friction, this alloy demonstrates corrosion and corrosion-related stress cracking resistance in seawater, chlorides and sulfides.

With its combination of properties, this alloy resists mechanical wear, thread damage, corrosion and erosion. The couplings are non-galling, so they do not damage production tubing, and they retain their strength even at elevated temperatures.

Bakken-tested

Materion partnered with Hess, one of the largest producers in the Bakken, to qualify and pilot the ToughMet sucker rod couplings in deviated wells with higher than normal failure rates. Hess noted that the couplings more than tripled the mean time between failures associated with couplings made of alternative materials.

Encouraged by the results observed in the field tests, the company installed the couplings in more than 400 of its Bakken wells and now uses the couplings as part of its standard production practice.

Materion is expanding the deployment of its ToughMet couplings with additional operators in several different shale plays. Now about 20 operators are running the couplings in the Bakken and Permian and in the Elk Hills Field in California. To facilitate access to the couplings for operators, Materion is establishing distributors in each of these regions so that the couplings are available from local inventory.

Permian perspective

Discovery Natural Resources LLC is a private oil and gas company that operates more than 1,000 wells in the Permian Basin. To date, the company has used the ToughMet couplings in about 20 wells in the Permian and is seeing positive results.

Discovery owns some wells that were failing every 60 to 90 days, specifically due to rod-on-tubing wear as a result of extreme deviation. The company piloted the ToughMet couplings as a solution and as a result significantly increased the run time on those wells.

Discovery reported that its longest running well with these couplings is more than 385 days without a failure. The company has four additional wells with the couplings installed that are past the 300-day mark. In addition, Discovery has doubled or tripled its run times.

Discovery pulled the rods out of one of the ToughMet test wells after a pump failure and inspected the couplings after three months of the well running. It would typically see significant tubing or coupling wear after this period in the ground but saw that the original stencils from the manufacture were still visible on the coupling (see image above). There was minimal wear observed on the couplings. For Discovery that was an early indication that the couplings reduced rod-on-tubing wear.

Sucker rod pumping in long deviated unconventional wells is especially challenging because of side-loading of rods. Sucker rods can buckle due to forces acting in compression at the bottom of the rodstring on downstroke.

If rod side loads are calculated at more than 100 lb, Discovery considers running ToughMet couplings in that area to increase the run time on that particular well. The company reported that ToughMet is becoming increasingly well-established in its operations. Now that the test phase is completed, the company is using more ToughMet couplings.

By utilizing a sucker rod coupling that actively mitigates coupling-on-tubing wear, operators are helping reduce downtime and improve production efficiencies by eliminating the need for more frequent workovers.

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Well’s Production prediction with Microseismic Technology

With efficiency being crucial when every dollar counts, operators in unconventional plays could add microseismic technology to fracture modeling methods to gain insight into permeability advances and better forecast production.

That’s according to Sudhendu Kashikar, vice president of completions evaluation for MicroSeismic Inc.

Understanding drainage volume and improved permeability of stimulated rock are essential to forecasting production, he said. Typically, several models are used to accomplish this, but the approach has its drawbacks.

A single frack model per stage ignores geological variations along the wellbore. Plus, a discrete fracture network (DFN) model is needed to determine how fracturing actually improves the permeability of stimulated rock, Kashikar said.

Microseismic techniques can simplify the workflow and help with production forecasting, Kashikar said during a webcast June 16.

“Technology and procedures were developed to discriminate the microseismic events and fractures described by these events, capturing propped versus unpropped fractures,” Kashikar said while describing Productive-stimulated rock volume (Productive-SRV) technology. “A rock volume capturing the proppant-filled refractures showed much better correlation to the cumulative production than the total stimulated rock volume.”

Productive-SRV technology estimates how much stimulated fracture remains open through proppant placement by using estimated target zone productivity, a DFN, propped fracture estimate and the Fat Fracture drainage estimate, according to MicroSeismic’s website.

Focus is usually on the location of the proppant, but focus should also be on the amount of improved permeability achieved within the SRV or the Productive-SRV, he said.

Understanding and measuring such improvements will lead to the next step in reservoir stimulation and production forecasting, he said.

Using microseismic data has proven beneficial in establishing a deterministic DFN, which shows fractures detected through seismic.

“For every microseismic event we describe a fracture plane. The size is guided by the magnitude, and the orientation comes from the focal mechanism,” he said. “This is much easier to do with surface microseismic.”

The model is calibrated to actual fluid volumes pumped for a well. A mass balance approach is used to fill the fractures with proppant starting from the wellbore moving outward until the proppant is consumed for that stage, Kashikar explained. Once the fracture network and the propped network have been established, a geocellular grid can be superimposed to obtain the SRV and productive SRV to capture the proppant-filled rock volume, he said.

“One advantage of this workflow is the ability to capture fracture intensity—the number of fractures, the orientation of these fractures—to quantify the permeability enhancement achieved,” Kashikar added.

Key steps for the production forecasting workflow are describing three reservoir volumes—the productive SRV (the propped fractures), total SRV (includes propped and unpropped fractures) and the permeability scalar for individual cells within each region to determine how permeability improved for neighboring cells.

This workflow, he said, captures not only the size and shape of the drainage volume but also permeability within the drainage volume.

The process is a big step forward, he said, in understanding and determining the effectiveness of hydraulic fracturing.

“Rather than relying on a single representative fracture model, we can fully and accurately capture the variable fracture geometry and fracture intensity for the entire length of the wellbore, providing a much better production forecast,” Kashikar said. “We can now use the productive stimulated rock volume and the stimulated rock volume with permeability scalars to directly and explicitly describe the reservoir volume in the reservoir simulator.”

Source: www.epmag.com

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Abandoned Well

An abandoned good is a well that has been perforated and then abandoned, for any number of reasons. Abandoned wells pose a health and safety risk around the world and are a cause of concern especially in suburban communities and formerly converting to the use of water wells for municipal water supply. Many regions have specific laws on abandoned wells and how they should be treated, with the aim of reducing the risk of pollution and damage to empty wells.

The risk of injury is clear: someone might fall into an abandoned pit and not be able to get out. The fall could injure or kill someone, and unless the help comes quickly, the victim of the fall could die in the pit. Especially if an abandoned person is in a remote area, it may take days to realize that someone has fallen into the pit. Abandoned water wells also pose a threat to wildlife for the same reason.

In the case of an abandoned well, the well can serve as a pollutant storage site and release these pollutants into the natural environment. These pollutants may include materials leaked from septic tanks, which can pose a threat to human health if groundwater enters an abandoned well. Abandoned oil and gas wells can also serve as a source of pollution, and releases unexpected or rockets of material could pose a risk to safety and health.

If a well is temporarily put out of use, it may be simply limited. Capping involves covering the good so that content is not accessible. Ideally, the cap must be clearly labeled and regularly checked to detect any signs of intrusion or damage that could indicate that the cap is about to fail. Capping is also not intended to be a permanent measure, and people can be penalized for not having to deal with abandoned and adequately if they leave a well covered for too long.

If a well is really abandoned and will not be reused, it must be sealed. The sealing lens is to restore the conditions that were present in the soil before the well was perforated. The seal is run by a well-drilled drill, and typically requires permission from any local authority to handle excavation and sealing of wells. Sealing should be done with care to avoid injuries and to properly seal the good so that the problems with abandoned good will not emerge in the future.

• Pumpjacks are often used in wells that produce little oil. Once it is more expensive to remove the oil than it earns, a well is often abandoned.
• An abandoned well can serve as a storage site for pollutants, which includes laundered septic tanks.

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How Much Methane Hydrates in the Earth

One can not fail to make a nod in the described picture, to a perspective that in the long run could potentially mitigate concerns, at least on the physical consistency of METAN's resources .

We're talking about HYDRATES of NATURAL GAS : solid compounds formed by water and gas (mostly CNG ), similar in appearance to dry ice.

It is estimated that in the oceans there are about 60 billion of billions of cubic meters of HYDRATES gas, from which, potentially you could get METHANE far exceed 100 times RESERVES estimated to CNG .

The HYDRATES of NATURAL GAS (or gas hydrates) are widespread in large areas of the planet.

They are predominantly formed under low temperature conditions and high pressures typical of oceanic seabed; but are also present in polar and sub-polar continental areas.

They are the result of the decomposition of organic material by the microorganisms present in the sediments, a process that determines the formation of METHANE .

In particularly low temperatures and high pressures - parameters that occur precisely in the seabed or in the areas covered by icy soil - METHANE molecules remain trapped in the ice resulting in hydrated gases.

The main sources of HYDROGEN gas are located along the margins of virtually all ocean platforms, at depths of between 500 and 4000 meters, with thicknesses of even hundreds of meters.

Any commercial exploitation of this hidden treasure at the bottom of the sea is anything but simple.

The problems are due not only to the marine environment and to the depth of the deposits, but above all to the difficulty of managing the present METHANE to bring it to the surface.

Hydrated gases are of metastable nature: if they change the ambient temperature and pressure conditions they pass quickly from solid to gaseous state, dissociating violently into the two water and methane components .

The problem is currently being investigated in many countries, with particular focus on Japan, Canada, the USA and Norway.

Italy is also doing research, thanks in particular to the activity of the National Oceanographic and Experimental Geophysical Institute (OGS), which has been involved in the development of geophysical methods for the purpose of identifying and quantifying the presence of hydrated gases for about ten years.

Research is carried out in numerous ocean areas, including Antarctica, where OCT researchers have recently discovered the first continental WATER gas field .

As for the concrete possibility of recovering this METAN and considering it as an energy reserve for the future, the first steps are moving now and there are still no short-term solutions that can be expected, even if the technological issues to solve do not seem to be prohibitive.

Apart from the great POTENTIAL of available energy, the greatest incentive for research into possible exploitable GIRATI gas fields is represented by their already widespread geographic location, which makes them particularly attractive at a time when, in the international energy market growing geopolitical variable.

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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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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.

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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.

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What is Drilling Mud

Fluid used in the drilling of wells. Drilling mud, also referred to as drilling fluid is one of drillingknowledge, is used to clear the hole of debris created during the drilling process, to cool the tip, and maintain the pressurized hole. The composition of the drilling mud used in the drilling process depends on the type of hole being drilled and the material to be bore. 

Drilling muds have been used to improve drilling operations for most of modern history. The water was used to smooth the surface material and remove scraps when they were drilled groundwater wells. contemporary drilling activities are much more sophisticated, and wells can reach miles below the surface in order to reach oil and natural gas.

The type of drilling mud used depends on the material drilled through, the technical requirements of the mud performance (viscosity and speed), cost and regulations. One of the primary functions of the drilling mud is to remove the shavings created by the drill hole. Because the wells are so deep it is impossible to remove the debris on the bottom without the use of some form of liquid. specialized Liquids are often used because they have high speed and viscosity, which allows them to move more easily when a drill both materials is in operation and to keep cutting suspended in the liquid when the drill is stopped.

The use of drilling mud, particularly specialized sludge using potentially hazardous chemicals is regulated. Regulations are used to ensure that the waste material is kept away from ground water, rivers and lakes, where pollution could cause the water to be safe and unusable for the public. Used drilling mud and sediment created during the drilling process can be used as pool treatments pumping in large pools.

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What Mud Fluid in drilling for ?

The drilling mud are primarily for:

1. to lubricate and cool the drill drilling that would otherwise warming, for the friction with the rock , quickly arrive at break.
2. Pipe on the surface of earth and rock fragments (commonly known by the English technical term for cutting ) produced by the action of the chisel.
3. Exercise a counter pressure hydrostatic hole at the bottom and along its walls discoveries (ie not tubate) to contain the leakage of the fluid layer and to avoid the risk of kick or in more severe cases the real eruption of the well.
4. Supporting walls of the hole (thanks to the pressure exerted by the hydrostatic load), in order to prevent landslides and loss of the punched hole. This feature is said that the mud must do "panel" that must practically "plaster" the walls of the well.
5. The most important properties of the drilling mud must be the "thixotropy", namely the characteristic that, at the time that the circulation in the pit stops, the sludge to be gelled fluid holding imprisoned in suspension the cutting resulting from the drilling. Otherwise these debris, stopping the circulation of the fluid, would fall to the bottom hole imprisoning the chisel and the "battery terminal part" drilling.

In the oil exploration monitoring geological of drilling muds, by analyzing the microscope of fragments of rock it allows to recognize the stratigraphy of the perforated rocky succession and provides the first indications of the characteristics petrophysical properties of the reservoir . 

Furthermore, the analysis by means of gas chromatographs , of the fluids contained in the outgoing mud from the well, provides important clues for the detection and recognition of mineralized levels to hydrocarbons.

In some cases similar muds are used temporarily to support the walls of trenches or over works of excavation of civil engineering within loose soil, prior to the implementation of their final completion.

Read More → What Mud Fluid in drilling for ?

Drilling Rigs Type

There are many different types of drilling rigs. Which rig selected depends on the specific requirements of each drill site. Roll your mouse over each picture to see what kind of rig it is.Its a good for drilling knowledge

Land Based Drilling Rigs - The land-based drilling rig is the most common type used for exploration. This site is using a conventional, land-based drilling rig that is smaller and more efficient than those used in the past.

Slim Hole Drilling Rig - A conventional drill bore might be 18 inches in diameter; a slimhole bore can be as little as 6 inches. A slimhole well drilled to 14,760 feet may produce one-third the amount of rock cuttings generated by a standard well. The size of the drill site can be as much as 75 percent smaller, since slimhole equipment requires less space than conventional equipment. However, slimhole drilling is not technically feasible in all environments.

Coiled Tubing Drill Rig - Conventional wells are drilled using sections of rigid pipe to form the drill string. In some cases, coiled tubing technology can replace the typical drill string with a continuous length of pipe stored on a large spool. This approach has many benefits, including reduced drilling waste and minimized equipment footprints, so it is especially useful in environmentally sensitive areas. This technology is best suited to re-entering existing wells, and when multiple casing wells are unnecessary.

Jackup Drill Rigs – These rigs may be used in relatively shallow water -- less than 300 feet deep. A jackup rig is a floating barge containing the drilling structure that is outfitted with long support legs that can be raised or lowered independently of each other. The jackup, as it is known informally, is towed onto location with its legs up and the barge section floating on the water. Once at the drilling location, the legs are jacked down onto the seafloor, and then all three legs are jacked further down. Since the legs will not penetrate the seafloor, continued jacking down of the legs raises the jacking mechanism attached to the barge and drilling package, and slowly lifts the entire barge and drilling structure to a predetermined height above the water. These rigs are extremely strong, since they have to withstand ocean storms and high waves. These rigs are moved by simply by moving the legs up and down, which makes them cost-effective and easily shifted out of harm's way during storms.

Semi-Submersible Rigs – Drilling in water deeper than 300 feet demands some kind of floating platform to hold the rig. Semi-submersible rigs are floating vessels supported on large pontoon-like structures that are submerged below the sea surface. As with jackup rigs, the operating decks are elevated as much as 100 or more feet above the pontoons on large steel columns. This design has the advantage of submerging most of the area of components in contact with the sea and minimizing loading from waves and wind. Semisubmersibles can operate in a wide range of water depths, including deep water. Semi-submersibles can either be attached to the ocean bottom using strong chains and wire cables or may utilize dynamic positioning to remain stationary during drilling without anchors.

Drill Ship - For exploration targets farther offshore, specially designed rigs mounted on ships can drill a well in water depths up to 10,000 feet. These rigs float and can be attached to the ocean bottom using traditional mooring and anchoring systems, or utilize dynamic positioning to remain stationary during drilling without anchors.

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Maritime transport on oil tankers

The shipping of oil on board tankers (tankers and super tankers carrying up to 400,000 tons of crude oil), represents more than half of world maritime trade. One can imagine the consequences of oil shortage on commercial! (On others for that matter ...).

Initially the oil was transported aboard wooden casks (barrels). The barrel has remained the unit of exchange used. It is 159 L. Now tankers are designed as huge reservoirs, sometimes divided into several compartments to store oil of different characteristics (including density). So we can better manage the weight distribution on the ship.

Over the past 30 years, many maritime disasters involving super-tankers have been held. They have caused ecological and economic disasters along the coast affected by oil spills. Most of the cleanup costs and compensation were supported by local e local governments. The Coastal Cleanup is in turn often provided by volunteers.

Since then, new oil transport ships are equipped with double hulls, which are supposed to reduce disaster risks. But they do not prevent the practice of degassing, responsible for oil spill at sea ... The single-hulled tankers still represent the vast majority of the park. 

The gigantic size of the super-tankers creates monstrous consumption of fuel, but which are reasonable compared to their carrying capacity. Currently, more than 600 tankers with a tonnage greater than 200,000 tonnes in circulation.

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Conclusion on the processing of oil

The oil must undergo many changes to be exploitable in the context of a specific use. These transformations involve multiple energy consumption, little known today (no doubt the oil industry have information on this issue). In the end, the multitude of products can be used in various ways (fuel, fuel, petrochemical, plastics, etc.).. 

These byproducts are sometimes directly recyclable (gasoline, diesel, etc.). sometimes they will suffer from further processing to be usable, some are even-products, which have no real opportunities. 

The tendency is to a maximum value of by-products, and the proportion of products derived is relatively fixed, Indutries oil must seek additional outlets for products produced in over-quantity. For example, the French fleet dieselisation pushes the quantities of products for which we must be sure the application or to find new markets.

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EOR - Enhanced Oil Recovery

When the reservoir pressure is insufficient, we proceed to the injection of fluid (s) to force oil to rise. These fluids may be gas (one of the deposit, or liquefied petroleum gas), or water.

Techniques more advanced (and more energy-intensive), such as thermal methods or fluid drive missible, allow to exploit the deposits difficult.

The thermal method involves heating the oil to the fluid (that is to say, reduce its viscosity). The heat comes from the injection of steam or underground combustion.

The fluid drive missible is performed using carbon dioxide or liquefied petroleum gas, lighter. Finally, chemical methods attempt to limit the capillary that holds the oil in the rocks. This is done using polymers or micro-emulsions of oil, water, alcohols and surfactants.

Read More → EOR - Enhanced Oil Recovery

State of the World's Oil Reserves

A simplified figure and relatively speaking: a cube of 7 kilometers from the side, half empty (or half full, it depends), with a leak rate equivalent to the Rhone is the current state of reserves and world oil consumption.

Proven reserves are generally estimated at between 140 and 160 Gt, or 1,050 to 1,200 Gbl. But taking into account technological advances and a recovery rate above 30%, the reserves could reach 266 Gt (or 1'996 GBL). The truth is that the reserves are not well known, and that in addition to proven reserves, it is quite inappropriate to make hypothetical assumptions about the probable reserves and ultimate.

Fairly coarse (and varies according to findings nouvaux oilfields), proven reserves are geographically distributed as follows:

• 55-60% in the Middle East;
• 15-18% in North America;
• 7-8% in Central and South America;
• 6-7% in Eastern Europe and Former Soviet Union;
• 6-8% in Africa;
• 3-5% in Asia and Oceania;
• 1-2% (!) In Western Europe;

I'll let you calculate how many tons or barrels this is by geographic area.

The countries of OPEC account for approximately 75-80% of total world proven reserves. Several sources say, however, that the state reserves of many countries been an overestimate: these optimistic data are primarily used to sit supremacy and economic influence of the major producing countries.

The rise in oil prices led to interest in deposits unconventional oil , such as oil sands, whose operation is known as energy-intensive, highly polluting, and catastrophic for the environment (despite some methods that allow to avoid the creation of open pits).

Global warming also affects some plan to use: the melting of arctic ice led some companies (such as Arctic Oil & Gas Corp) interest in the exploitation of hitherto inaccessible deposits.

Finally, the exploitation of new (types of) deposits appears to be the preferred track to generate more wealth to the detriment of the fight against global warming and more generally the protection of the environment. Or how to cut ever more ardently the branch on which we sit ...

Read More → State of the World's Oil Reserves