The papers in this month’s issue relate to the manner in which an oil field is developed, and provide contributions in the areas of improving well stimulation, improving fracturing performance, and improving fractured reservoir productivity. Appropriate to the current low oil price environment, each of these papers represent timely contributions that increase our body of practical knowledge on how to maintain or increase oil reservoir productivity while minimizing costs.
Field Treatment To Stimulate an Oil Well in an Offshore Sandstone Reservoir Using a Novel, Low-Corrosive, Environmentally Friendly Fluid addresses the challenge of acidizing sandstone formations effectively with environmentally-sustainable chemical formulations in the face of varied mineral components, acidic gases, corrodible well tubulars, elevated temperatures, and, of course, crude oil. Hisham Nasr-El-Din et al. demonstrate the applicability of a novel chelating agent that has already shown promise in carbonate reservoirs, and which extensive testing, development, and laboratory-scale proof-of-concept work previously had shown should also work well in sandstone reservoirs. In the present work, they describe the culmination of this work in a real-world stimulation field test in a sour oil well in an offshore sandstone reservoir.
Tight Cardium Multistage-Fractured Horizontal-Oil-Well-Performance Study Focusing on the Effectiveness of Various Fracture-Fluid Systems is intended to improve the productivity of Canada’s largest conventional light oil field, the Pembina Cardium, for which the overall recovery factor is quite low (approximately 17%), leaving a large target for future production. Murray Reynolds et al. have focused on the growing interest in multistage-fractured horizontal wells as a means to increase recovery from this field. Between the early 1990s and 2013, more than 1,400 horizontal wells were drilled in the Pembina Cardium, and the fracture-fluid systems used span a range of non-energized and energized (gas containing) fluids, including ‘slickwaters,’ gels, and foams. This provides a rich body of approaches and production histories from which the authors have derived new best-practice recommendations.
Efficiency of Steam-Over-Solvent-Injection-in-Fractured-Reservoirs (SOS-FR) Method Considering Oil Recovery and Solvent Retrieval: Core-Scale Experimentation deals with a thermal/solvent enhanced-oil-recovery process that can be applied to fractured carbonates or to oil-sand reservoirs following a cold production phase. The potential is to increase oil-recovery efficiency while using less steam than a solely thermal process, but effective solvent retrieval is essential. The SOS-FR method involves three phases: steam and/or hot water injection to reduce the oil viscosity (with oil recovery mainly by thermal expansion and gravity drainage); then solvent injection to further reduce the viscosity (with oil recovery mainly by gravity); then steam and/or hot water injection to retrieve the solvent (and possibly further increase oil recovery). M. Almojtaba Mohammed and Tayfun Babadagli address the optimization of the most important process performance factors: oil recovery, recovery rate, and solvent retrieval. I think you will find that each of these papers is relevant to today’s operating environment as well as tomorrow’s, and I believe that each one succeeds in answering some questions from the past, providing new knowledge that can be applied now, and identifying new questions for further work that may provide keys to future technology advances. I recommend that you take the time to read and consider them all.
Laurier L. Schramm, Ph.D., P.Chem., C.Dir., FCIC
President and CEO, Saskatchewan Research Council,
Issue Coordinator, JCPT
About the Issue Coordinator
Laurier Schramm has more than 35 years of research and development experience spanning each of the industry, not-for-profit, university, and government sectors. He is currently President and CEO of the Saskatchewan Research Council (SRC), which he has led to become one of Canada’s premier innovation-enabling organizations with exponential revenue growth, and a solid track-record of over CDN 6 billion-worth of demonstrable economic impacts in Saskatchewan alone. Schramm’s previous positions have included Vice-President, Energy with the Alberta Research Council, President and CEO with the Petroleum Recovery Institute, and Senior Research Scientist with Syncrude Canada Limited. His interests include technological innovation, management and leadership, colloid and interface science, and nanotechnology. Schramm holds 17 patents, and has published 11 books and more than 350 other publications and proprietary reports. Many of his inventions have been adopted into commercial practice. Schramm has served on many expert advisory panels and boards, is cofounder of Innoventures Canada Incorporated (I-CAN), and cofounder of Canada’s Innovation School™. He has received national scientific and engineering awards for his work, and is a Fellow of the Chemical Institute of Canada and is an honourary member of the Engineering Institute of Canada. Schramm is currently focused on helping SRC to become Canada’s leading technological innovation enabler.
Field Treatment To Stimulate an Oil Well in an Offshore Sandstone Reservoir Using a Novel, Low-Corrosive, Environmentally Friendly Fluid discusses the application of new chelant to remove formation damage caused by calcium carbonate particles. Field treatments highlight the capability of the chelant to remove the damage effectively, while maintaining the integrity of well tubulars and without causing sand production or sludges, which are common when HCl is used. Chelants can be used in sandstone wells when these wells are equipped with corrosion-resistant alloys, have an electrical submersible pump, or smart completion.
Tight Cardium Multistage-Fractured Horizontal-Oil-Well-Performance Study Focusing on the Effectiveness of Various Fracture-Fluid Systems is a case study reviewing one of the key aspects of any hydraulic-fracturing campaign—does fracture-fluid design make a difference in well ultimate recoveries, and is there any value in using premium fracture fluids vs. slickwater? This study reviewed the production performance of 148 horizontal oil wells located in five major Cardium areas in Alberta, from cost, ultimate recovery, and net present value perspectives. The results showed that in four out of the five areas studied, there was significant value in using a premium energized fracture-fluid system.
Efficiency of Steam-Over-Solvent-Injection-in-Fractured-Reservoirs (SOS-FR) Method Considering Oil Recovery and Solvent Retrieval: Core-Scale Experimentation provides a new experimental design to measure the solvent retrieval during solvent-based heavy-oil recovery processes. After immersing the core samples to hydrocarbon solvents to recover heavy oil, they were exposed to hot water to retrieve the solvent. The retrieval of solvent diffused into matrix was mainly caused by the evaporation of the solvent at elevated temperatures and imbibition of hot water into rock if the originally oil-wet samples become more water-wet during the solvent immersion phase. The amount of solvent retrieved through these processes were determined and the efficiencies were analyzed for different parameters including rock wettability, oil viscosity, solvent type, solvent-soaking period, rock type, boundary conditions, and different combinations of steam-solvent cycle, and temperature applied.