The success of organic shale development in North America has brought a great interest in organic shale exploitation internationally. The employed drilling and completion practices are based on the techniques that have been successful in US, and hydraulic fracturing treatments are primarily dominated by slickwater owing to its low cost and benefit in maximizing the stimulated reservoir volume (SRV). However, the international shale plays are usually in high tectonic stress environment, complex geological structures, and frequently contain natural fractures, which are quite different from most of the plays in US with relatively simple structure and more relaxed stress environment. These complexities have resulted in additional challenges in both reservoir understanding and completions, and ultimately production performance. Proppant placement issues and casing deformation are commonly experienced in slickwater treatments in these tectonically active plays, and production results were below expectations in the early phase of the development. Numerous studies have been performed and revealed the stress sensitivity in all the wells in which the fracture system starts to deteriorate when the effective stress reaches the critical value, resulting in many perforation clusters not contributing to production. This leads to an important conclusion that fracture conductivity is equally important as the SRV for high stress organic shale plays, and the treatment strategy shall be recalibrated from current slickwater treatments. The presentation provides an overview of challenges in these organic shale plays with high tectonic stresses, and highlights a few important findings and practices that would address the problem and improve production performance.
Liu Hai is Technical Advisor on production and stimulation in Schlumberger, and Domain Manager for Middle East and Asia region. He has been with the company for 17 years and worked in various positions in Asia, Middle East and Texas. Previously he was with the Production Technology Research Institute of PetroChina Xinjiang for 6 years. His primary areas of expertise are in reservoir, production and stimulation. He has authored or coauthored more than 20 technical papers. He holds a BS degree in computer science from Xi’an Petroleum College of China, and a MS degree in petroleum engineering from Heriot-Watt University.