Enhanced Oil Recovery Lecture Notes
Sinikka Curz
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.
Transit worker and rider safety is a top priority for the Biden-Harris Administration and the U.S. Department of Transportation. Public transit is a safe form of transportation. Transit workers should expect a safe workplace and riders should expect a safe trip.
FTA resources can be used by transit agencies to prevent and address crime in their systems and protect transit workers and riders. These resources also can be used for overtime pay for enhanced security personnel presence, mental health and crisis intervention specialists.
Transit Customer Assault Prevention
To improve transit safety for riders, FTA recently published a new Transit Customer Assault Prevention webpage for transit agencies to provide more resources to help prevent and address crime in their systems, which includes research on the factors contributing to customer assault events, trends in assault data and mitigations.
The virtual Assault Awareness and Prevention for Transit Operators (Direct Delivery) course provides transit bus operators with prevention strategies necessary to reduce the likelihood of assault incidents.
The virtual Assault Awareness and Prevention for Transit Operators (Train the Trainer) course is designed to provide transit agency instructional staff with the support necessary to deliver the Assault Awareness and Prevention course within their agencies. Each registered participant will receive an electronic instructor package that will include an instructor guide, course slides, instructor notes and the participant workbook.
The goal of this course is to provide participants with knowledge and skills to prevent, respond to and recover from workplace violence. Prevention methods covered include implementing system and personal security measures, recognizing and reporting the warning signs of potentially violent behavior and using effective interpersonal skills for dealing with different types of people. Response strategies focus on self-preservation and the importance of accurate reporting. The recovery module addresses the stress associated workplace violence and what employees can do to address the impact of it on themselves and co-workers.
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]
Studies from our center on emergency ERAS for perforated duodenal ulcer [1] and emergency small-bowel surgery [2] also established its feasibility and safety and documented its successful implementation. In both studies, there was a significant reduction in the length of hospital stay in the ERAS group with no increase in postoperative complications. In contrast to other studies that used limited intra- and postoperative care elements, the authors maximized the use of ERAS care elements in the study population, including the preoperative components whenever feasible and most of the intraoperative and postoperative components.
Subsequently, a study by Sharma et al documented the use of ERAS in emergency settings in patients with perforation and intestinal obstruction and found it to be safe and feasible. [9] In a report examining the safety and efficacy of an ERAS program in patients undergoing emergency laparotomy for trauma, Purushothaman et al found that the ERAS group had significant reductions in duration of hospital stay (3.3 1.3 vs 5.0 1.7 d) and in time to removal of nasogastric tubes (1.1 0.1 vs 2.2 0.9 d), urinary catheters (1.1 0.1 vs. 3.5 1.6 d), and drains (1.0 0.2 vs 3.7 1.6 d), indicating that ERAS can be successfully used in abdominal trauma, as in other abdominal emergency conditions. [10]
Greater awareness, additional trials with larger populations, and further work on identifying and eliminating the factors hindering implementation of ERAS will be the keys to integrating emergency ERAS into day-to-day practice. Every effort should be made to implement as many components of ERAS as possible in the context of an emergency setting.
In this article, we will summarize the various pre-, intra-, and postoperative components of emergency ERAS. We will also briefly discuss discharge criteria, further follow-up, and complications, with a final note on barriers to and limitations of implementation of ERAS protocols in emergency settings.
The body goes into a catabolic state during surgery, as various stress hormones and inflammatory mediators are released in response to stress, which in turn leads to insulin resistance. [11, 12] The resistance largely depends on the complexity of the surgical procedure: the more complex the procedure, the greater the resistance, with the greater resistance leading to increased morbidity and prolonged recovery. Hyperglycemia correlates directly with reduction in muscle mass, which leads to infections, cardiovascular events, and poor mobilization. [13] Implementing ERAS care elements reduces surgical stress and aims at maintaining normoglycemia, thereby reducing morbidity.
In a conventional ERAS protocol, the preoperative phase includes various components, such as preadmission counseling, fluid and carbohydrate loading, no prolonged fasting, no or selective bowel preparation, antibiotic prophylaxis, thromboprophylaxis, use of nonopioid analgesics, and no premedication. [14]
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