The severe loading conditions experienced by the casing strings in thermal wells used in Cyclic Steam Stimulation (CSS) and Steam Assisted Gravity Drainage (SAGD) operations pose a significant challenge in terms of the casing connection sealability performance and integrity. The industry has recently developed standards and protocols for assessing and qualifying connection sealing performance for such applications. The comprehensive programs include both Finite Element Analysis (FEA) evaluations and a series of full-scale physical tests. The FEA evaluations are required to determine the worst-case connection design scenarios, in terms of geometry, material properties and make-up torque, for fabrication of the specimens to be assessed in the physical tests. The scope of the FEA work includes analyzing the connection sealability performance under selected load cases representative of the intended field service conditions. A suitable minimum sealability criterion is required to assess the adequacy of the predicted connection sealing performance for the specific application. This paper presents the results from an experimental metal-to-metal seal investigation and describes their use to establish a simplified sealability criterion for premium casing connections. The leakage response of several different seal samples was determined as a function of contact stress level for differential gas pressures of 3.3, 7.4, 12.1 and 16.5 MPa, corresponding to Application Severity Levels (ASL) of 240, 290, 325 and 350 per ISO/PAS 12835. The test results were used to characterize the relationship that existed between the leakage rates recorded in the tests and the selected control variables: differential pressure; seal length; tubular size; and seal contact stress level. The paper also demonstrates the use of the proposed sealability evaluation criterion in conjunction with the FEA results established for a 244.5 mm, 59.5 kg/m L80 premium connection subjected to thermal cycle loading.

Thermal well service conditions have presented a significant challenge to the sealability of casing connections. Over the years, industry has established various standards, protocols and guidelines for assessing the sealability performance of casing connections to be used in thermal well applications. The use of Finite Element Analysis (FEA) has been increasingly incorporated into the connection performance evaluation process. FEA evaluation requires the use of an appropriate criterion that relates the connection seepage rates to the applied internal pressure differential, contact stress profile on the radial seal surface, surface roughness, thread compounds and various other factors such as environmental impacts. This paper presents experimental work that has been undertaken to investigate the metal-to-metal seal behavior in premium casing connections. The physical tests simulated a series of metal-to-metal seals under various levels of gas pressure and seal contact stress. The impacts of seal length, tubular diameter, surface roughness, thread compound and corrosive medium were investigated. The experimental results were used to validate the sealability criterion which is proposed for use in evaluating thermal well casing connections.

Technology Focus This feature focuses on the development and trial evaluation of selected new technologies to improve recovery, reduce energy use and environmental impacts, and enhance the overall economics of in-situ extraction of heavy-oil and bitumen resources. Facing formidable technical challenges and lower returns relative to conventional oil plays, the heavy-oil industry traditionally has demonstrated creativity, embraced innovation, and supported the assessment of bold new approaches to achieve improved recovery. The nonthermal, in-situ recovery method called slurrified heavy-oil-reservoir extraction (SHORE) described in one summarized paper certainly represents a novel approach with potential to achieve very high recovery in certain reservoir settings. The complexities involved in modeling and testing this recovery process push several technical-capability limits, and learnings from the rigorous feasibility assessment will undoubtedly provide ancillary benefits in these areas. While the use of downhole electrical-heating systems as a means to enable or improve heavy-oil recovery is certainly not a new idea—extensive patent and technical literature exists on this subject—there is growing interest by operators in state-of- the-art system designs and approaches for use in a variety of applications. This includes the most basic application where resistive heating systems are deployed in long horizontal wells to reduce flow losses and achieve more-uniform inflow through the active heating of the wellbore and near-wellbore region of the reservoir. This approach has been applied recently by several different operators in both onshore and offshore heavy-oil applications. Another summarized paper demonstrates that the use of even these relatively simple systems in an offshore well can be very challenging but also very effective. Other recent SPE papers describe ongoing technology developments and field piloting efforts to assess the performance/success of various forms of in-well electromagnetic systems for direct reservoir heating and oil recovery. The application of such systems represents an example of the changing oil field where the scientific and technological knowledge involved extends well beyond traditional petroleum-engineering boundaries. Also garnering attention is a new generation of autonomous inflow-control devices that passively adapt to changing downhole conditions to restrict the entry of unwanted fluids (e.g., water or steam) into horizontal wells. Operators are also exploring new steam-assisted-gravity-drainage and cyclic-steam-stimulation well-optimization capabilities that rely on the combined use of inflow-control-device completions and feedback-controlled injection and production operations. Several recent papers describe workflows and present results from comprehensive reservoir simulations that suggest this approach can be effective in achieving more-uniform recovery and lower steam/oil ratios in highly heterogeneous bitumen reservoirs. It will be interesting to watch the pace of development and uptake of these technologies. Finally, one additional-reading paper describes technology developments that address the ongoing challenges heavy-oil operators face in obtaining accurate flow measurements. JPT Recommended additional reading at OnePetro: www.onepetro.org. SPE 165064 First Heater Cable Installed in Colombia by W. Acosta, Hocol, et al. SPE 165547 A Performance Comparison Study of Electromagnetic Heating and SAGD Process by Manyang Liu, University of Regina, et al. OTC 24503 ICD/AICD for Heavy Oil—Technology Qualification at the Peregrino Field by I. Leitao Junior, Statoil, et al. SPE 167414 Inflow-Control Devices Improve Production in Heavy-Oil Wells by Brandon Least, Halliburton, et al. SPE 165388 Control of Reservoir Heterogeneity in SAGD Bitumen Processes by Terry W. Stone, Schlumberger, et al.

Technology Focus With interest in heavy oil continuing to grow rapidly worldwide, SPE has responded to the need for increased dissemination of technical information related to the exploitation of these unconventional hydrocarbon resources. In one new initiative, SPE joined forces with the Canadian Society for Unconventional Gas to organize the 2010 Canadian Unconventional Resources and International Petroleum Conference in Calgary, in October. SPE also organized heavy-oil advanced-technology workshops and expanded heavy-oil content of regularly scheduled conferences in several Middle East countries, Russia, and China in 2010, signaling the growing importance of heavy-oil reserves to these regions. I often get asked: “What is the best recovery method to use for this heavy-oil reservoir?” The answer can vary substantially, depending on the reservoir setting and fluid properties. Therefore, as with any new field, the process of determining the preferred development strategy begins with a detailed and accurate characterization of the reservoir and fluid properties. However, in the case of heavy oil, unanticipated technical challenges are encountered routinely in accomplishing this basic exercise. For example, while tools and equipment are readily available and proved for capturing live downhole-fluid samples in conventional-oil reservoirs, this is not the case for heavy oils, especially those with in-situ viscosities exceeding several hundred centipoises, let alone thousands or tens of thousands of centipoises. Many heavy-oil reservoirs consist of unconsolidated sand formations, which also makes it difficult to acquire either fluid or undisturbed core samples and then to obtain accurate permeability and porosity data. For thermal projects, determining accurate rock and fluid properties as a function of temperature is important but is not an easy task. Specialized equipment and field-sampling/laboratory-testing techniques along with ample experience typically are required to obtain reliable data. It is also worth noting that the trend over the past few years has been to give much more attention during initial development planning to the sequencing of different enhanced-oil-recovery (EOR) strategies to maximize recovery from heavy-oil reservoirs. On the basis of the many papers written this past year related to polymer flooding of heavy-oil reservoirs, it appears that recent technological advancements and application successes have led to this becoming a viable EOR alternative for a wide range of in-situ fluid viscosities. Finally, the need for conducting pilot operations to establish actual reservoir and well performance and to validate expectations cannot be emphasized enough. Heavy Oil additional reading available at OnePetro: www.onepetro.org SPE 137639 “Thermal Properties of Formations From Core Analysis: Evolution in Measurement Methods, Equipment, and Experimental Data in Relation to Thermal EOR” by Y.A. Popov, Schlumberger, et al. SPE 134849 “In-Situ Heavy-Oil Fluid-Density and -Viscosity Determination Using Wireline Formation Testers in Carbonates Drilled With Water-Based Mud” by Ridvan Akkurt, Saudi Aramco, et al. SPE 136665 “Viscosity of Foamy Oils” by A.B. Alshmakhy, SPE, Weatherford, et al.

Summary Understanding of material properties for tubular design under high-pressure/high-temperature (HP/HT) conditions goes well beyond the basics of the classic methods routinely used in the industry. Coupon test results of high-strength tubulars commonly used in HP/HT wells are presented to demonstrate the temperature and strain-rate dependencies of the stress-strain response. Based on the coupon test results, analytical equations and advanced nonlinear Finite Element Analysis (FEA) are used to illustrate the substantial impact that the temperature and rate-dependent material properties have on pipe body and connection performance in HP/HT applications. This paper raises an awareness of the importance of strain-rate effects, and recommendations are made on a few special considerations to account for these effects in well tubular design for elevated temperature applications. In addition, the findings also provide the basis for a critical discussion of the applicable American Society for Testing and Materials (ASTM)/American Petroleum Institute (API) test standards and the need to understand the effect of different strain/loading rates that may be used in material characterization and full-scale testing of tubular products at elevated temperatures. Collectively the information and results presented in the paper are expected to be very useful to the new generation of engineers charged with the tubular design for challenging well applications involving elevated temperature and severe load conditions.