Co2 Enhanced Oil Recovery Process
Melia Hazinski
Crude oil development and production in U.S. oil reservoirs can include up to three distinct phases: primary, secondary, and tertiary (or enhanced) recovery. During primary recovery, the natural pressure of the reservoir or gravity drive oil into the wellbore, combined with artificial lift techniques (such as pumps) which bring the oil to the surface. But only about 10 percent of a reservoir's original oil in place is typically produced during primary recovery. Secondary recovery techniques extend a field's productive life generally by injecting water or gas to displace oil and drive it to a production wellbore, resulting in the recovery of 20 to 40 percent of the original oil in place.
However, with much of the easy-to-produce oil already recovered from U.S. oil fields, producers have attempted several tertiary, or enhanced oil recovery (EOR), techniques that offer prospects for ultimately producing 30 to 60 percent, or more, of the reservoir's original oil in place. Three major categories of EOR have been found to be commercially successful to varying degrees:
The EOR technique that is attracting the most new market interest is CO2-EOR. First tried in 1972 in Scurry County, Texas, CO2 injection has been used successfully throughout the Permian Basin of West Texas and eastern New Mexico, and is now being pursued to a limited extent in Kansas, Mississippi, Wyoming, Oklahoma, Colorado, Utah, Montana, Alaska, and Pennsylvania.
Until recently, most of the CO2 used for EOR has come from naturally-occurring reservoirs. But new technologies are being developed to produce CO2 from industrial applications such as natural gas processing, fertilizer, ethanol, and hydrogen plants in locations where naturally occurring reservoirs are not available. One demonstration at the Dakota Gasification Company's plant in Beulah, North Dakota is producing CO2 and delivering it by a 204-mile pipeline to the Weyburn oil field in Saskatchewan, Canada. Encana, the field's operator, is injecting the CO2 to extend the field's productive life, hoping to add another 25 years and as much as 130 million barrels of oil that might otherwise have been abandoned.
In September 2010, DOE competitively selected seven Next Generation CO2 EOR research projects. Four projects are developing techniques for mobility control of the injected CO2. Novel foams and gels have the potential to prevent the highly-mobile CO2 from channeling through high-permeability areas of a reservoir, leaving un-swept, unproductive areas of the reservoir. The four projects are:
Enhanced Oil Recovery (EOR) injection wells are used to increase production and prolong the life of oil producing fields. Secondary Recovery is an EOR process, commonly referred to as waterflooding. In this process, salt water co-produced with oil and gas is reinjected into the oil producing formation to drive oil into pumping wells, resulting in the recovery of additional oil. Tertiary Recovery is an EOR process that is used after secondary recovery methods become inefficient or uneconomical. Tertiary recovery methods include the injection of gases, enhanced waters and steam in order to maintain and extend oil production.
Statewide Rule 46 governs fluid injection into reservoirs productive of oil, gas, or geothermal resources. Applications for a permit is on Railroad Commission Forms H-1 and H-1A. The rule also addresses matters regarding: the application process; notice and opportunity for hearing; protested applications; special equipment requirements (e.g., tubing and packer) and modification, suspension, or termination of permits for one or more of several causes. Also included in Statewide Rule 46 are requirements regarding records maintenance monitoring and reporting testing plugging, and penalties for violations of the rule. Permit revocation may result as a consequence of noncompliance.
Class II wells are used only to inject fluids associated with oil and natural gas production. Class II fluids are primarily brines (salt water) that are brought to the surface while producing oil and gas. It is estimated that over 2 billion gallons of fluids are injected in the United States every day. Most oil and gas injection wells are in Texas, California, Oklahoma, and Kansas.
During oil and gas extraction, brines are also brought to the surface. Brines are separated from hydrocarbons at the surface and reinjected into the same or similar underground formations for disposal. Wastewater from hydraulic fracturing activities can also be injected into Class II wells.
The injected fluids thin (decrease the viscosity) or displace small amounts of extractable oil and gas. Oil and gas is then available for recovery. In a typical configuration, a single injection well is surrounded by multiple production wells that bring oil and gas to the surface.
The UIC program does not regulate wells that are solely used for production. However, EPA does have authority to regulate hydraulic fracturinghydraulic fracturingThe process of using high pressure to pump sand along with water and other fluids into subsurface rock formations in order to improve flow of oil and gas into a wellbore. when diesel fuels are used in fluids or propping agents. During hydraulic fracturing, another enhanced recovery process, a viscous fluid is injected under high pressure until the desired fracturing is achieved, followed by a proppant such as sand. The pressure is then released and the proppant holds the fractures open to allow fluid to return to the well.
Extraction of oil and gas usually produces large amounts of brine. Often saltier than seawater, this brine can contain toxic metals and radioactive substances. Brines can damage the environment and public health if discharged to water or land. Deep underground injection of brines in formations isolated from underground sources of drinking water prevents soil and water contamination.
When states began to implement rules preventing disposal of brine to surface water bodies and soils, injection became the preferred way to dispose of this waste fluid. All oil and gas producing states require the injection of brine into the originating formation or similar formations.
Under Section 1422 enhanced recovery wells may either be issued permits or be authorized by rule. Disposal wells are issued permits. The owners or operators of the wells must meet all applicable requirements, including strict construction and conversion standards and regular testing and inspection.
In 2014 EPA released information clarifying UIC program requirements for underground injection of diesel fuels in hydraulic fracturing. The Agency also released guidance for EPA permit writers implementing UIC Class II requirements.
We have remained at the forefront of medicine by fostering a culture of collaboration, pushing the boundaries of medical research, educating the brightest medical minds and maintaining an unwavering commitment to the diverse communities we serve.
Enhanced Recovery After Surgery (ERAS) at Massachusetts General Hospital is a patient-centered, evidence-based approach to surgical care that empowers you, the patient, to be a partner in your own care. Because all commonly performed procedures at Mass General set their standards to ERAS, you can be confident that you will receive best-known care before, during and after your procedure.
The ERAS team consists of clinicians involved in your care throughout the entire process, including pre-procedure preparation, the procedure itself, anesthesia, perioperative services, pharmacy, nursing, post-operative care and follow-up.
Mass General teams shares more about how the ERAS program is designed to ensure better preparation and recovery following colorectal procedures. Below, please access these videos in multiple languages:
The Center for Outcomes and Patient Safety in Surgery (COMPASS) combines clinical collaboration and data to ensure, amongst all surgical and procedural colleagues, the safest, most appropriate and effective and highest quality procedure for every patient, every time.
We use cookies and other tools to enhance your experience on our website and to analyze our web traffic. For more information about these cookies and the data collected, please refer to our Privacy Policy.
The components of ERAS may be broadly divided into preadmission, preoperative, intraoperative, and postoperative phases, each of which includes various distinct components (see the image below). In emergency settings, the limited preadmission and preoperative periods pose challenges to the management of ERAS pathways; however, a multidisplinary approach enables the maximum possible implementation of care elements in all phases of an ERAS protocol. [1, 2, 3]
A number of subspecialties have started implementing ERAS in their patients and have shown improved postoperative outcomes. However, there remains some hesitation to implement ERAS in emergency settings, arising from the expected difficulty of properly executing all of the components of an ERAS protocol, especially the preoperative components (see below).
A better understanding of ERAS principles has led to the publication of many studies reporting on the use of ERAS in emergency settings. [4, 5, 6, 1, 2, 7] The pioneers in this regard were Gonenc et al, who studied the outcomes of ERAS in patients undergoing laparoscopic repair of a perforated duodenal ulcer. [6] They reported a better outcome in the ERAS group with implementation of only the postoperative components of ERAS. This report was followed by a few other studies that evaluated the applicability and feasibility of ERAS in emergency surgical settings ranging from simple closure of a perforated peptic ulcer to major abdominal operations. [1, 2, 7, 3]
A study by Roulin et al comparing patients who underwent elective colectomy and urgent colectomy found that most of the ERAS elements could be applied to emergency colectomy. [8] In a retrospective cohort of 370 patients undergoing emergency major abdominal procedures, Wisely et al reported shorter hospital stays and better outcomes in the ERAS group. [7]
c80f0f1006