No abstract

In many cases, carbonate oil wells are stimulated with open hole acid flush or acid fracturing treatments to increase productivity. Some of the challenges with fracturing stimulation are reservoir related, such as consistently stimulating all targeted intervals and intersecting the natural fracture network. The growth of hydraulic fractures in the vertical direction is difficult to predict, leading to the risk for entering unsought gas or water-bearing formation. Operations can be complex, costly and pose environmental challenges. A multilaterals stimulation technology (MST) has been developed and field tested to be a simple, efficient and more controllable method of stimulation with less environmental impact. The method uses less fluid, reduces the risk of groundwater contamination and eliminates stimulation fluid flowback disposal. This paper discusses the evolution of the technology, leading to the first pilot installation in a horizontal well in the Austin Chalk carbonate reservoir in Texas, during April of 2014. The pilot installation proved the stimulation technology's efficiency by creating 60 laterals, each 40 feet long, in a few hours pumping time. This installation is believed to be a world record for creating 60 laterals in less than 5 hours. The well's production response was significant, and productivity index was increased by 30 times compared to before the stimulation.

The ubiquitous challenge that is faced by chemical stimulation techniques, of any kind, has always been achieving an economic and efficient distribution of the stimulation solution across the exposed reservoir interval. Many have approached this problem from a chemical perspective and others from the use of additives for mechanical diversion; however the very nature of stimulation itself means that a changing injection profile will make efficient diversion by such techniques uncertain and unpredictable. Instead, rather than relying on serendipitous deployment techniques, the approach described and reported here places true mechanical diversion as part of the well construction process. This paper will completely describe the process and achievements to date, including successful application in a number of horizontal wells completed in the Austin Chalk, as part of an overall deployment plan.Essentially, this new completion system comprises of multiple pressure actuated assemblies, distributed along the liner/casing. These assemblies, when activated, allow the lateral deployment of forty-foot needles, radially distributed at ninety-degree phasing around the casing, into the unstimulated reservoir. These subs can be precisely located across pre-selected intervals and thereby provide certainty of acid treatment distribution. The acid is pumped through the needles themselves during stimulation; however production takes place through a suite of ports. A bespoke debris basket may be run, after the stimulation treatment, in order to recover a suite of needle deployment indicators. This run, if performed, effectively establishes the success of the deployment.In order to demonstrate the concept and avoid the high-cost environment of the North Sea, a low cost field trial location was sought and identified. An Austin chalk operator was looked for that had an extensive horizontal candidate well set available for re-completion in open-hole. A number of candidate wells were then identified and the wells were recompleted and stimulated with this new system. This paper will present the entire suite of data related to these deployments, stimulation operations, lessons learned, production impact and potential. This novel technology was greatly assisted, supported and delivered via the Joint Chalk Research (JCR) council, comprising of some ten operating companies that encourage, fund and drive the development of carbonate completion and stimulation solutions.

Introduction: We evaluated correlates of seeking treatment among ACS patients in a rural, medically underserved community. This study is unique because patient data came from medical records and physician-administered structured interviews and it is the first to evaluate correlates of treatment delay in a rural and medically underserved patients. Methods: A physician-administered structured interview was administered to 170 consecutive ACS patients. Patients were recruited from June 2010-December 2012. Inclusion criteria were: 1) chest pain or discomfort with onset outside hospital; and 2) fulfilling the criteria for ACS (i.e., chest pain or discomfort, changes on the ECG and/or an increase in at least one biochemical marker. The structured interview was composed of standardized questions with pre-defined answer categories covering 10 domains: 1) Patient demographics; 2) Presenting symptoms (e.g., first symptoms and type of symptom; symptom intensity/progression, symptom description and knowledge, etc.); 3) Responses to symptoms (e.g., informed someone, summoned help); 4) Symptom context (e.g., activity at time of AMI, place it occurred); 5) factors associated with decision to seek help (e.g., distance to hospital, transportation available, how transported, money, etc.); 6) Psychological/Personality factors (e.g., current depression, anxiety, denial patterns, personality types A or B); 8) Technology use (e.g., time spent watching TV or using smart devices/internet, etc.); 9) Prior cardiac history and risk factors (e.g., history of hypertension, diabetes, obesity, hyperlipidemia, medications, ER laboratory data); and 11) Post admission clinical course (e.g., ECG, arrhythmias, lytic therapy, CCU days, PCI, CABG, TIMI score , complications). Late presentation was defined as greater than 90 minutes for STEMI patients and greater than 180 minutes for NSTEMI patients. Results: Among STEMI patients (n=98), only marital status (currently married vs. not married; OR=0.3; CI=0.1-0.9) and concerns about money (OR =26.3; CI = 1.2-500.0) were significantly associated with late presentation for treatment. For NSTEMI patients (n=73), several presenting symptom variables were associated with seeking treatment early including whether they experienced pain radiating to the arms (OR=0.1; CI=0.0-0.59), describing their chest pain as heavy (OR=0.04; CI=0.0-0.4), and reporting that nitroglycerin relieved chest pain (OR=0.2; CI = 0.1-0.9). One post-admission variable (whether they had Acute PCI post-MI; OR=0.1; CI=0.0-0.7) also was associated with late treatment. Conclusions: Being unmarried or having concerns about money were associated with delays in treatment for STEMI patients, while mostly symptom-related variables were associated with treatment delays among NSTEMI patients in this cohort of low-income, medically underserved patients.

In many cases, carbonate oil wells are stimulated with open hole acid flush or acid fracturing treatments to increase productivity. Some of the challenges with fracturing stimulation are reservoir related, such as consistently stimulating all targeted intervals and intersecting the natural fracture network. The growth of hydraulic fractures in the vertical direction is difficult to predict, leading to the risk for entering unsought gas or water-bearing formation. Operations can be complex, costly and pose environmental challenges. A multilaterals stimulation technology (MST) has been developed and field tested to be a simple, efficient and more controllable method of stimulation with less environmental impact. The method uses less fluid, reduces the risk of groundwater contamination and eliminates stimulation fluid flowback disposal. This paper discusses the evolution of the technology, leading to the first pilot installation in a horizontal well in the Austin Chalk carbonate reservoir in Texas, during April of 2014. The pilot installation proved the stimulation technology's efficiency by creating 60 laterals, each 40 feet long, in a few hours pumping time. This installation is believed to be a world record for creating 60 laterals in less than 5 hours. The well's production response was significant, and productivity index was increased by 30 times compared to before the stimulation.