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Results
Summary Newly developed drilling automation systems locate a computer interface between commands issued by the driller and instructions transmitted to the drilling machinery. Such functions are capable of faster and more precise control than can be achieved by an unaided operator and thus can help drilling within narrow margins. To ensure that these systems work properly in all circumstances, an advanced drilling simulator has been developed to enable testing under a wide range of simulated conditions. The environment described in this paper uses hardware in the loop (HIL) simulation to verify that the automation techniques being tested respond correctly in real time. Rigorously validated physical models of the drilling process simulate the response of the well to the commands given to the drilling machines. Abnormal drilling conditions (e.g., packoffs, kicks) and equipment or machine-related problems (e.g., plugged nozzles, power shortage) are convincingly recreated. The drilling simulator models the behavior of surface equipment such as the activation of gate valves to line up different pits or the flow in the mud return. It simulates changes in the drilling fluid properties when mixing additives to the mud. It is therefore possible to focus training sessions on cooperation between different groups at the wellsite. This is particularly useful when planning the introduction of drilling automation that involves new work procedures as a result of automation and adaptation of the drilling team to a new operational environment. Drilling operations are becoming more and more complex. Automation has the potential to provide large improvements in efficiency and safety, but automation technologies must be implemented correctly at the workplace. Just as the aviation industry has used simulated environments for decades, drilling simulation environments are the key to the safe and successful implementation of drilling automation and the development of crew skills to face future challenges.
- North America > United States (1.00)
- Europe > Norway (0.94)
- Information Technology > Communications (1.00)
- Information Technology > Architecture > Real Time Systems (0.35)
Summary During drilling operations, downhole conditions may deteriorate and lead to unexpected situations that can result in significant delays. In most cases, warning signs of the deterioration can be observed in advance, and by taking proactive actions, drillers can avoid serious incidents such as packoffs or stuck pipes. A new analysis methodology, relying on an automatic real-time computer system, has been developed to detect those early indicator conditions. The methodology involves constantly computing the various physical forces acting inside the well (mechanical, hydraulic, and thermodynamic). These physical forces are coupled by an automatic model calibration, which then gives a reliable picture of the expected well behavior. Through analysis of the deviations between modeled and measured values, an estimation of the current state of the well is derived in real time. Changes in the well condition are an early warning of deteriorating well conditions. This paper precisely describes the real-time analysis and the results during some drilling operations. The software has been used for monitoring 15 unique wells located in five different North Sea fields. All major situations were signaled in advance at different event time scales: Rapidly changing downhole conditions (such as pulling a drillstring into a cuttings bed) were typically detected 30 minutes ahead of the actual event, medium-duration deteriorations were detected up to 6 hours before the incident, and slow-changing downhole conditions were signaled up to 1 day in advance. Several examples that illustrate the detected incidents over distinct time periods are described. The availability of good-quality real-time data streams makes it possible to implement such analysis tools in an integrated operation setup. Early symptom detection can be used to make decisions in a timely fashion, on the basis of quantitative performance indicators rather than subjective feelings and personal experience.
- North America > United States (1.00)
- Europe > United Kingdom > North Sea (0.61)
- Europe > Norway > North Sea (0.61)
- (2 more...)
Summary The Schoonebeek heavy-oil field was first developed by Nederlandse Aardolie Maatschappij B.V. (NAM) in the late 1940s. Because of economics, it was abandoned in 1996. In 2008, the Schoonebeek Redevelopment Project, using a gravity-assisted-steamflood (GASF) design concept, was initiated with 73 wells (44 producers, 25 injectors, and 4 observation wells). Steam injection and cool-down cycles subject a cement sheath to some of the most severe load conditions in the industry. Wellbore thermal modeling predicted that surface and production sections would experience temperatures in excess of 285°C (545°F) and considerable stress across weak formations. A key design requirement was long-term integrity of the cement sheath over an expected 25- to 30-year field life span. Complicating this requirement was the need for lightweight cementing systems, because lost-circulation issues were expected in both hole sections, particularly in the mechanically weak Bentheim sandstone. The long-term integrity challenge was divided into chemical and mechanical elements. Prior research on high-temperature cement performance by the operator provided necessary guidance for this project. Laboratory mechanical and analytical tests were conducted to confirm the high-temperature stability of the chosen design. In addition to using lightweight components, foaming the slurry allowed the density, mechanical, and economic targets to be met. A standardized logistical plan was put in place to allow use of the same base blend for the entire well, adjusted as needed, using liquid additives, and applying the foaming process when necessary. This single-blend approach greatly simplified bulk-handling logistics, allowing use of dedicated bulk-handling equipment. The first well was constructed in January 2009; all 73 wells have been successfully cemented to surface. The steaming process, initiated in May 2011, has progressed with no well integrity issues to date.
- North America > United States (1.00)
- Europe > Netherlands > North Sea > Dutch Sector (0.50)
- Geology > Petroleum Play Type > Unconventional Play > Heavy Oil Play (1.00)
- Geology > Geological Subdiscipline > Geomechanics (0.93)
- Geology > Rock Type > Sedimentary Rock > Clastic Rock > Sandstone (0.35)
- Europe > Netherlands > North Sea > Dutch Sector > Schoonebeek License > Bentheim Sandstone Formation (0.99)
- Europe > Netherlands > North Sea > Dutch Sector > Schoonebeek Field > Bentheim Sandstone Formation (0.99)
- Europe > Netherlands > Coevorden Field > Z3 Carbonate Formation (0.98)
- (6 more...)
- Well Drilling > Wellbore Design > Wellbore integrity (1.00)
- Well Drilling > Pressure Management > Well control (1.00)
- Well Drilling > Drilling Operations (1.00)
- (7 more...)
Summary A 52-well heavy-oil field development that targeted shallow—a 3,400- to 4,000-ft true vertical depth (TVD)—sands on the North Slope of Alaska was initiated in 2008. Horizontal wells of 11,000- to 13,000-ft measured depth (MD) were drilled early in the program. These initial wells served as "data-gathering and technology-proving" opportunities leading up to the eventual 23,000-ft-MD wells. Key technical challenges include equivalent-circulating-density (ECD) and drag management. ECD management became essential in the 8½-in. production-hole section of the longer wells. A relatively narrow (<600 psi) mud-weight (MW) window necessitated changes to casing, drillstring, drilling fluids, and operational parameters. Lighter-weight production casing allowed the drilling of a larger production hole (8¾-in. vs. 8½-in.). A tapered drillstring, reduced mud rheology, and reduced flow rate all became a necessary part of the ECD-management solution. Advanced drag-management techniques are required to install the 9⅝-in. production casing, 5½-in. production liner, and 4½ × 3½-in. intelligent inner-string completion. The 9⅝-in. casing is installed by use of the "buoyancy assist" method (i.e., "flotation") so it may be "pushed" and reamed in the hole beyond the point of negative weight. The lower completion consists of a 5½-in. slotted liner with swell packers. Centralizers on the liner were changed from nonrotating to fixed, which allowed breaking axial drag while reaming the liners to depth. Extensive torque-and-drag modeling was used to plan intelligent inner-string completions on the injector wells, which included injection control devices, swell packers, and a fiber-optic distributed temperature sensor (DTS) to monitor injectivity. This full-length paper discusses the technical challenges, well-design solutions, and operational practices that were trialed and implemented to enable extended-reach wells to be successfully drilled on the edge of the industry-experience envelope, with all wells meeting targeted objectives.
- North America > United States > Alaska > Nikaitchuq Field > Schrader Bluff Formation (0.99)
- North America > United States > Alaska > Schrader Bluff Formation (0.98)
Surge-and-Swab Pressure Predictions for Yield-Power-Law Drilling Fluids
Crespo, Freddy (University of Oklahoma) | Ahmed, Ramadan (University of Oklahoma) | Enfis, Majed (University of Oklahoma) | Saasen, Arild (Det norske oljeselskap and University of Stavanger) | Amani, Mahmood (Texas A&M University at Qatar)
Summary Surge and swab pressures have been known to cause formation fracture, lost circulation, and well-control problems. Accurate prediction of these pressures is crucially important in estimating the maximum tripping speeds to keep the wellbore pressure within specified limits of the pore and fracture pressures. It also plays a major role in running casings, particularly with narrow annular clearances. Existing surge/swab models are based on Bingham plastic (BP) and power-law (PL) fluid rheology models. However, in most cases, these models cannot adequately describe the flow behavior of drilling fluids. This paper presents a new steady-state model that can account for fluid and formation compressibility and pipe elasticity. For the closed-ended pipe, the model is cast into a simplified model to predict pressure surge in a more convenient way. The steady-state laminar-flow equation is solved for narrow slot geometry to approximate the flow in a concentric annulus with inner-pipe axial movement considering yield-PL (YPL) fluid. The YPL rheology model is usually preferred because it provides a better description of the flow behavior of most drilling fluids. The analytical solution yields accurate predictions, though not in convenient forms. Thus, a numerical scheme has been developed to obtain the solutions. After conducting an extensive parametric study, regression techniques were applied primarily to develop a simplified model (i.e., dimensionless correlation). The performance of the correlation has been tested by use of field and laboratory measurements. Comparisons of the model predictions with the measurements showed a satisfactory agreement. In most cases, the model makes better predictions in terms of closeness to the measurements because of the application of a more realistic rheology model. The correlation and model are useful for slimhole, deepwater, and extended-reach drilling applications.
- Europe (1.00)
- Asia (0.68)
- North America > United States > Texas (0.29)
- North America > United States > California (0.28)
- Research Report > Experimental Study (0.67)
- Research Report > New Finding (0.46)
- Well Drilling > Wellbore Design > Wellbore integrity (1.00)
- Well Drilling > Pressure Management > Well control (1.00)
- Well Drilling > Drilling Operations (1.00)
- (2 more...)
Unique Process and Tool Provides Better Acid Stimulation and Better Production Results
Al-Saqabi, Mishari (Kuwait Oil Company) | Gazi, Naz (Kuwait Oil Company) | Vishwanath, Chimmalgi (Kuwait Oil Company) | Al Bahrani, Hasan (Kuwait Oil Company) | Turkey, Naween (Kuwait Oil Company) | Abdul-Razaq, Eman (Kuwait Oil Company) | Al-Zankawi, Omran (Kuwait Oil Company) | Bouland, Ali (Kuwait Oil Company) | Surjaatmadja, Jim B. (Halliburton) | Al Hamad, Abdulla M. (Halliburton) | Brand, Shannon (Halliburton)
Abstract There are many ways to stimulate an unlined openhole horizontal well using acid. The simplest way is to just pump acid into the well (i.e., bullhead) without placement control. However, this can often be ineffective. Although still used, such approaches can create massive enlargements at the entry point or high injectivity area, thus causing ineffective treatments and re-entry issues. Wellbore collapse often follows. The use of coiled tubing (CT) as a "pin-point" delivery method is therefore preferred. Using CT allows dispersal of the acid either uniformly or intermittently along the lateral, as desired. CT also allows acid washing to be performed, which is another common process that can improve stimulation without much additional expense to the operator. Using a jetting tool with many jets, acid can be sprayed onto the wellbore wall, and the active agitation caused by the acid-wash process increases the chemical reactivity of the acid at the desired locations. Another beneficial approach of using CT is the hydrajet assisted acid fracturing (HJAAF) method. With focused jetting of acid at much higher pressures, the process initiates microfractures in the wellbore walls. When etched with acid, this approach effectively bypasses near-wellbore (NWB) damage much deeper than common washes, thus providing much better results. Further modification of the process by exerting high annular pressures offers the capability of delivering medium to large fractures. This paper discusses two HJAAF processes uniquely combined into one process used in two large horizontal wells. Because of the large dimension of the inner diameter (ID) of the wells combined with the small production tubing the tool must pass through, the implementation had to be further improved by using a unique jetting mechanism, which positioned the jet nozzles closer to the target. Actual results of such stimulations are presented.
- North America > United States (0.94)
- Asia > Middle East > Kuwait (0.30)
Abstract Fracture ballooning usually occurs in naturally fractured reservoirs and is often mistakenly regarded as an influx of formation fluid, which may lead to misdiagnosed results in costly operations. In order to treat this phenomenon and to distinguish it from conventional losses or kicks, several mechanisms and models have been developed. Among these mechanisms under which borehole ballooning in naturally fractured reservoirs take place, opening/closing of natural fractures plays a dominant role. In this study a mathematical model is developed for mud invasion through an arbitrarily inclined, deformable, rectangular fracture with a limited extension. A governing equation is derived based on equations of change and lubrication approximation theory (Reynolds's Equation). The equation is then solved numerically using finite difference method. Considering an exponential pressure-aperture deformation law and a yield-power-law fluid rheology has made this model more general and much closer to the reality than the previous ones. Describing fluid rheology with yield-power-law model makes the governing equation a versatile model because it includes various types of drilling mud rheology, i.e., Newtonian fluids, Bingham-plastic fluids, power-law, and yield-power-law rheological models. Sensitivity analysis on some parameters related to the physical properties of the fracture shows how fracture extension, aspect ratio and length, and location of wellbore can influence fracture ballooning. The proposed model can also be useful for minimizing the amount of mud loss by understanding the effect of fracture mechanical parameters on the ballooning, and for predicting rate of mud loss at different formation pressures.
- Asia > Middle East (0.93)
- North America > United States > California (0.46)
- Overview > Innovation (0.50)
- Research Report (0.34)
Abstract The success of recent applications in underbalanced drilling (UBD) and managed pressure drilling (MPD) has accelerated the development of technology in order to optimize drilling operations. The increased number of depleted reservoirs and the necessity for reducing formation damage has also increased the need to apply UBD/MPD to such candidate fields. Several methods used the latest mechanistic multiphase flow models in order to predict bottomhole circulation pressure when performing UBD/MPD operations. A new model is developed that utilizes the latest mechanistic multiphase flow models; the developed model calculates the bottomhole circulation pressure as a function of surface injection rates, choke pressure and time. The developed model can be used in designing and optimizing UBD/MPD operations in terms of determining the correct injection rate and/or choke pressure. In addition, the developed model is used to utilize the reservoir energy to attain correct bottomhole conditions. The developed model in addition to utilizing the latest mechanistic models also reduce the error in calculating the bottom hole pressure by incorporating an algorithm in which the injection rates are calculated in-situ rather than assuming constant injection rates. The model is validated against data from literature and against a commercial simulator. Results show that the developed algorithm has increased the accuracy in predicting bottomhole pressure by incorporating the changes in new gas and liquid injection rates.
- North America > United States > Texas (0.95)
- Europe (0.94)
- Research Report > New Finding (0.48)
- Research Report > Experimental Study (0.34)
Abstract Root cause analysis (RCA) is a class of problem solving methods aimed at identifying the root causes of problems/ incidents. By directing corrective measures at core causes, it is hoped that the chances of problem recurrence will be minimized. Thus, RCA is frequently considered to be an iterative process, and is frequently viewed as a tool of continuous improvement. RCA, initially is a reactive method of problem detection & solving. This means that, the analysis is done after an incident has occurred. By gaining proficiency in RCA it becomes a pro-active method. This means that RCA is able to estimate the possibility of an incident even before it could occur. Root cause analysis mainly consists of three steps A): Define the problem. B): Analyze the problem. C): Find the solutions for the problem. In view of the accident which took place recently i.e. Gulf of Mexico oil spill 2010, there were eight catastrophic failures which led to the explosion that destroyed the Deepwater Horizon drilling rig in the Gulf of Mexico. These failures included the sending of unofficial cement by specialist cementing services, no indications of testing done on the surface by drilling rig provider company before deploying it, pressure test which would have revealed problems in the drill was incorrectly deemed as a success by operator company and drilling rig provider company rig personnel. A complex and interlinked succession of mechanical failures, human judgments, engineering design, operational implementation and team interfaces caused this tragedy. Consequences of these plain errors were quite hazardous. It affected the humanity, environment, economy and also the settlements. The core objective of the paper is to bring about a detailed analysis so as to throw light on new techniques and how they can be utilised to prevent such disasters. To achieve this objective we acknowledged all the possible solutions for this issue so that the most excellent solutions can be selected and the challenges that are to be faced are studied thoroughly and examined to prevent future errors. However, it is recognized that complete prevention of reappearance by a single intrusion is not always possible. On the belief that problems are best solved by attempting to correct or eliminate root causes, as opposed to merely addressing the immediately obvious symptoms.
- North America > United States > Gulf of Mexico > Central GOM > East Gulf Coast Tertiary Basin > Mississippi Canyon > Block 252 > Macondo Field > Macondo 252 Well (0.99)
- North America > Canada > Alberta > Fire Field > Acl Et Al Fire 8-15-114-7 Well (0.89)
- Europe > Norway > Norwegian Sea (0.89)
Abstract The development of arctic resources requires wells to be drilled, cased, andcemented through permafrost. Permafrost presents unique challenges, especiallyto cementing operations, requiring a cement system with the capability toperform in the subfreezing permafrost environment. The performance required isthat the cement provides isolation, exhibits low heat of hydration, and setswith sufficient strength to provide casing support. There are also specifictesting requirements detailed in API recommended practices. In the polar region, there are several approaches used in the design of cementsystems. The approaches used in Russia, Canada, and USA (Alaska) areillustrated. The design considerations take into account local conditions andrequirements and use knowledge from cementing practices employed in thedrilling industry. It is important to understand the current cementing practices in use withinthe arctic region. This will allow future improvements as more developmenttakes place and the resources become exploited. Introduction To be successful, hydrocarbon resource development in arctic regions mustmeet the challenges posed by drilling, casing, and cementing wells throughpermafrost layers in the remote arctic environment. The Russian Far East, forexample, is almost completely covered in permafrost and holds significant gasreserves that remain largely untapped due to the remoteness of the area and thecomplexity of drilling through the permafrost layers. Offshore operations areadditionally impacted by sea ice, which does not directly affect cementingoperations; however, the short operational window certainly requires detailedplanning and reliable performance. The remoteness of arctic locations affects all aspects of development, impacting overall logistics: access, timing, and materials delivery andstorage. In addition, several of the challenges faced during the initialdevelopment phases affect the subsequent cement job and cementing practices. These challenges need to be addressed as part of the overall development plan;they include borehole maintenance, casing centralization, and mud conditioningand removal, and all require careful consideration of the permafrost.
- Europe (1.00)
- North America > United States > Texas (0.46)
- North America > United States > Colorado (0.28)
- (2 more...)
- Well Drilling > Drilling Fluids and Materials > Drilling fluid selection and formulation (chemistry, properties) (1.00)
- Well Drilling > Drilling Fluids and Materials > Drilling fluid management & disposal (1.00)
- Well Drilling > Casing and Cementing > Cement formulation (chemistry, properties) (1.00)
- Well Drilling > Casing and Cementing > Casing design (0.94)