Well stimulation (or simply stimulation) is a treatment process to enhance or repair the productivity of a well. It basically creates or improves the flow of the mineral underneath the ground. The minerals flow from the reservoir in the formation to the wellbore, from where they are pumping out of the ground and will go transportation.
What is the purpose of well stimulation?
Dec 11, 2020 · Well Stimulation Treatment (WST) refers to processes performed on oil and gas wells to increase production. The various types of WST enhance the permeability of the geologic formation containing oil and gas. The Geologic Energy Management Division (CalGEM) oversees WST in California.
What is a stimulation treatment?
well stimulation. 1. n. [Enhanced Oil Recovery, Well Workover and Intervention, Well Completions, Shale Gas] A treatment performed to restore or enhance the productivity of a well. Stimulation treatments fall into two main groups, hydraulic fracturing treatments and matrix treatments. Fracturing treatments are performed above the fracture pressure of the reservoir formation and …
What are well stimulation vessels?
Well stimulation treatment is defined in regulation as “a treatment of a well designed to enhance oil and gas production or recovery by increasing the …
What type of acid is used in well stimulation?
Well stimulation (or simply stimulation) is a treatment process to enhance or repair the productivity of a well. It basically creates or improves the flow of the mineral underneath the ground. The minerals flow from the reservoir in the formation to the wellbore, from where they are pumping out of the ground and will go transportation.
What is the purpose of well stimulation?
What are the well stimulation methods?
What is well activation?
What is reservoir well stimulation?
What is an oil well workover?
Which of the following well stimulation technique is performed below the fracture pressure of the formation?
Why is nitrogen well activated?
What is skin in well?
What does workover mean in oil and gas?
What is a stimulation vessel?
Also known as "Multipurpose drilling vessels", these ships replace the conventional drilling oil rig, thus resulting in considerable savings in cost.
What is fracturing fluid?
What is completing a well?
How does horizontal well stimulation work?
Horizontal well stimulation usually involves creating multiple fractures along the wellbore using different well completion techniques. These multiple fractures generate large contact areas with the reservoir and also increase reservoir permeability. The multistage fracturing of a single or multiple horizontal wells is usually carried out either in simultaneous or sequential manner. In simultaneous fracturing, the multiple fractures are initiated and propagated at the same time ( Fig. 1.1 ), whereas in sequential fracturing the fractures are created from one cluster after another in a well, usually by keeping the previously created fractures either propped or pressurized with fluid ( Rodrigues et al., 2007; Soliman et al., 2008 ). Simultaneous or sequential fracturing is carried out in multiple wells and is called the “zipper” fracturing technique.
Can well stimulation cause formation damage?
Significant formation damage can occur during well stimulation operations, much of which is associated with incompatibility between the fracturing fluids and the formation water and/or the reservoir mineralogy. Methods to mitigate this effect include modifying the composition of the injected fluids in various ways.
What is the main threat to corrosion?
The main corrosion threat here is related to high concentration of hydrogen ions present at the low inherent acid pH. Acid formulations may use corrosion inhibitors developed for carbon steel or for CRAs such as 13% chromium steels.
What is hydraulic fracturing?
Hydraulic fracturing is a well-stimulation technique that is most suitable to wells in low- and moderate-permeability reservoirs that do not provide commercial production rates even though formation damages are removed by acidizing treatments. Hydraulic fracturing jobs are carried out at well sites using heavy equipment including truck-mounted pumps, blenders, fluid tanks, and proppant tanks. A hydraulic fracturing job is divided into two stages: the pad stage and the slurry stage. In the pad stage, fracturing fluid is injected into the well to break down the formation and create a pad. During the slurry stage, the fracturing fluid is mixed with sand/proppant in a blender and the mixture is injected into the pad/fracture. This chapter presents a brief description of hydraulic fracturing treatments covering formation fracturing pressure, fracture geometry, productivity of fractured wells, hydraulic fracturing design, and post-frac evaluation.
What is the process of acidizing a well?
Acidizing a well consists of injecting acid (usually hydrochloric acid) into the well. In limestone or carbonate formations, the acid dissolves portions of the rock in the formation, opening up existing spaces to allow for the flow of petroleum.
How to get hydrocarbons out of a formation?
Another method of ensuring the efficient flow of hydrocarbons out of a formation is well treatment, which is a type of well stimulation that consists of injecting acid, water, or gases into the well to open up the formation and allow the petroleum to flow through the formation more easily.
What is well stimulation?
Well stimulation is a well intervention performed on an oil or gas well to increase production by improving the flow of hydrocarbons from the reservoir into the well bore. It may be done using a well stimulator structure or using off shore ships / drilling vessels, also known as " Well stimulation vessels ".
What is hydraulic fracturing?
Hydraulic fracturing, also called fracking, fracing, hydrofracking, fraccing, frac'ing, and hydrofracturing, is a well stimulation technique involving the fracturing of bedrock formations by a pressurized liquid. The process involves the high-pressure injection of "fracking fluid" (primarily water, containing sand or other proppants suspended with the aid of thickening agents) into a wellbore to create cracks in the deep-rock formations through which natural gas, petroleum, and brine will flow more freely. When the hydraulic pressure is removed from the well, small grains of hydraulic fracturing proppants (either sand or aluminium oxide) hold the fractures open.
When was hydraulic fracturing first used?
Hydraulic fracturing began as an experiment in 1947, and the first commercially successful application followed in 1950. As of 2012, 2.5 million "frac jobs" had been performed worldwide on oil and gas wells, over one million of those within the U.S.
What are the environmental impacts of fracking?
Opponents of fracking argue that these are outweighed by the environmental impacts, which include groundwater and surface water contamination, noise and air pollution, and the triggering of earthquakes, along with the resulting hazards to public health and the environment.
What is gas lift?
Gas lift is sometimes considered a form of stimulation, particularly when it is only used for starting up the well and shut off during steady state operation. More commonly though, lifting as a stimulation refers to trying to lift out heavy liquids that have accumulated at the bottom, either through water entry from the formation or through chemicals injected from surface such as scale inhibitors and methanol (hydrate inhibitor). These liquids sit at the bottom of the well as can act as a weight holding back the flow of reservoir fluids, essentially acting to kill the well. They can be removed by circulating nitrogen using coiled tubing .
Noteworthy papers in OnePetro
Clinkenbeard, P., Bozeman, J. F., & Davidson, R. D. 1958. Gas Well Stimulation Increases Production and Profits. Society of Petroleum Engineers. http://dx.doi.org/10.2118/1067-G .
External links
Xiong, Hongjie. "Optimizing Cluster or Fracture Spacing: An Overview." The Way Ahead. Society of Petroleum Engineers. 25 May 2017. https://www.spe.org/en/twa/twa-article-detail/?art=3007
What is a horizontal well?
A directionally drilled well that drills down vertically and then turns to become near parallel with the ground surface is considered a horizontal well. Of the wells stimulated in 2014, 15, or 2.2%, were reported as horizontally drilled.
What is the WST requirement?
The WST regulations require operators to evaluate the casing, tubing, and cement lining of the wellbore borehole to ensure that the well’s construction is more than adequate to withstand operations that are intended to increase the permeability of the hydrocarbon producing formation.
What is hydraulic fracturing?
Hydraulic fracturing, (also known as hydrofracturing, “fracking”, or “fracing”) is the process of creating small cracks, or fractures, in underground geological formations to allow oil or natural gas to flow into the wellbore and thereby increase production. Prior to initiating hydraulic fracturing, engineers and geologists study and model ...
What is Well Stimulation?
Well stimulation (or simply stimulation) is a treatment process to enhance or repair the productivity of a well. It basically creates or improves the flow of the mineral underneath the ground. The minerals flow from the reservoir in the formation to the wellbore, from where they are pumping out of the ground and will go transportation.
Types of Oil Well Stimulation
Well stimulation falls under two categories: hydraulic and matrix. Essentially, there are three types or methods of well stimulation.
Why is Well Stimulation Important?
As discussed above, stimulation may not only be necessary for new wells but also existing ones. A reservoir that requires stimulation is classified as unconventional because it doesn’t have a consistent or speedy natural flow.
Conclusion
Well stimulation or reservoir stimulation is crucial for initiating and restoring the productivity of an oil or gas well. Hydraulic fracturing is the most common method today, especially with the advent of shale oil.
How does horizontal well stimulation work?
Horizontal well stimulation usually involves creating multiple fractures along the wellbore using different well completion techniques. These multiple fractures generate large contact areas with the reservoir and also increase reservoir permeability. The multistage fracturing of a single or multiple horizontal wells is usually carried out either in simultaneous or sequential manner. In simultaneous fracturing, the multiple fractures are initiated and propagated at the same time ( Fig. 1.1 ), whereas in sequential fracturing the fractures are created from one cluster after another in a well, usually by keeping the previously created fractures either propped or pressurized with fluid ( Rodrigues et al., 2007; Soliman et al., 2008 ). Simultaneous or sequential fracturing is carried out in multiple wells and is called the “zipper” fracturing technique.
Can well stimulation cause formation damage?
Significant formation damage can occur during well stimulation operations, much of which is associated with incompatibility between the fracturing fluids and the formation water and/or the reservoir mineralogy. Methods to mitigate this effect include modifying the composition of the injected fluids in various ways.
What is hydraulic fracturing?
Hydraulic fracturing is a well-stimulation technique that is most suitable to wells in low- and moderate-permeability reservoirs that do not provide commercial production rates even though formation damages are removed by acidizing treatments. Hydraulic fracturing jobs are carried out at well sites using heavy equipment including truck-mounted pumps, blenders, fluid tanks, and proppant tanks. A hydraulic fracturing job is divided into two stages: the pad stage and the slurry stage. In the pad stage, fracturing fluid is injected into the well to break down the formation and create a pad. During the slurry stage, the fracturing fluid is mixed with sand/proppant in a blender and the mixture is injected into the pad/fracture. This chapter presents a brief description of hydraulic fracturing treatments covering formation fracturing pressure, fracture geometry, productivity of fractured wells, hydraulic fracturing design, and post-frac evaluation.
How is shale oil extracted?
Extracting shale oil from the ground uses a drilling method known as “hydraulic fracking.” It is a well stimulation technique in which shale rock is fractured by a pressurized liquid. The process involves the high-pressure injection of “fracking fluid” (primarily water, containing sand or other proppants (either sand or aluminum oxide) suspended with the aid of thickening agents) into a wellbore to create cracks in the deep-rock formations through which natural gas, petroleum, and brine will flow more freely. When the hydraulic pressure is removed from the well, small grains of the hydraulic fracturing proppants hold the fractures open. Hydraulic fracturing in the USA basically began commercially around 1950. As of 2012, approximately 2.5 million “frac jobs” had been performed worldwide on oil and gas wells with over 1 million of those were located within the United States.
Why is stimulation performed on a well?
Stimulation is performed on a well to increase or restore production. Sometimes, a well initially exhibits low permeability, and stimulation is employed to commence production from the reservoir. Other times, stimulation is used to further encourage permeability and flow from an already existing well that has become under-productive.
What is the process of acidizing a well?
Well acidizing is achieved by pumping acid into the well to dissolve limestone, dolomite and calcite cement between the sediment grains of the reservoir rocks. There are two types of acid treatment: matrix acidizing and fracture acidizing.
How does matrix acidizing work?
While matrix acidizing is done at a low enough pressure to keep from fracturing the reservoir rock, fracture acidizing involves pumping highly pressurized acid into the well, physically fracturing the reservoir rock and dissolving the permeability inhibitive sediments .
What is HCI used for?
Also, HCI can be combined with a mud acid, or hydrofluoric acid (HF), and used to dissolve quartz, sand and clay from the reservoir rocks. In order to protect the integrity of the already completed well, inhibitor additives are introduced to the well to prohibit the acid from breaking down the steel casing in the well.
What is matrix acid?
A matrix acid job is performed when acid is pumped into the well and into the pores of the reservoir rocks. In this form of acidization, the acids dissolve the sediments and mud solids that are inhibiting the permeability of the rock, enlarging the natural pores of the reservoir and stimulating flow of hydrocarbons.
Overview
Extending the perforation tunnels and fractures
In cased hole completions, perforations are intended to create a hole through the steel casing so that the reservoir can be produced. The holes are typically formed by shaped explosives that perforate the casing and create a fractured hole into the reservoir rock for a short distance. In many cases, the tunnels created by the perforation guns do not provide enough surface area and it becomes desirable to create more area in contact with the wellbore.
Cleaning the formation
The assortment of drilling fluid pumped down the well during drilling and completion can often cause damage to the surrounding formation by entering the reservoir rock and blocking the pore throats (the channels in the rock throughout which the reservoir fluids flow). Similarly, the act of perforatingcan have a similar effect by jetting debris into the perforation channels. Both these situations reduce the permeability in the near well bore area and so reduce the flow of fluids int…
Lifting the well
Some stimulation techniques do not necessarily mean altering the permeability outside the well bore. Sometimes they involve making it easier for fluids to flow up the well bore having already entered. Gas liftis sometimes considered a form of stimulation, particularly when it is only used for starting up the well and shut off during steady state operation. More commonly though, lifting as a stimulation refers to trying to lift out heavy liquids that have accumulated at the bottom, either …
Well stimulation vessels
In more recent times, due to the temporary nature of well stimulation, specialized drilling ships known as "well stimulation vessels" have been used for deep sea well stimulation. Offshore companies such as Norshore and Schlumberger operate a fleet of such specialized ships. Also known as "Multipurpose drilling vessels", these ships replace the conventional drilling oil rig, thus resulting in considerable savings in cost. Some WSV's such as the "Norshore Atlantic" are able t…
See also
• Well intervention
• Well kill
• Oil reservoir
Common Stimulation Treatments
- Acid injection to dissolve formation damage
Consider adding a description.
Multimedia
- Published on Oct 16, 2014 Gerrit Nitters, Head of Well Stimulation and Impairment Prevention Research at Shell, presented “Well Stimulation – A New Challenge” during the 2005-2006 Society of Petroleum Engineers Distinguished Lecturer Series.
Noteworthy Papers in OnePetro
- Clinkenbeard, P., Bozeman, J. F., & Davidson, R. D. 1958. Gas Well Stimulation Increases Production and Profits. Society of Petroleum Engineers. http://dx.doi.org/10.2118/1067-G. Dusterhoft, R. 2006. Overview: Well Stimulation (July 2006). Society of Petroleum Engineers. http://dx.doi.org/10.2118/0706-0050-JPT. Nnanna, E. J., & Ajienka, J. A. (2005, January 1). Critic…
External Links
- Xiong, Hongjie. "Optimizing Cluster or Fracture Spacing: An Overview." The Way Ahead. Society of Petroleum Engineers. 25 May 2017. https://www.spe.org/en/twa/twa-article-detail/?art=3007