Theoretical understanding and technical practice of shale oil development in continental faulted basins in eastern China： A case study of Jiyang shale oil

Abstract

The shale oil in the continental faulted basins in eastern China，represented by Jiyang shale oil，has made a breakthrough in production capacity. However，Jiyang shale oil faces great challenges in achieving high and stable production due to the large burial depth and thickness，low maturity，high formation temperature and pressure，and poor oil flow capacity. Based on the production practice of more than 90 horizontal wells and 10 000-meter cores，the ternary-element storage and flow theory of “storage，fracture，and pressure” was deepened，and the key technology system of Jiyang shale oil development，such as three-dimensional fine evaluation of sweet spots of shale oil development，policy optimization for three-dimensional development technology，and three-dimensional balanced fracturing technology，was formed under the guidance of the theory. Theoretical research and practice show that pores and multi-scale and multi-type micro-fractures constitute a double reservoir system，which is the material basis for high and stable production and controls the reservoir space and the law of oil and gas accumulation. The support fractures and the hydraulic fractures are coupled to form a double fracture system with a scale of nanometer to centimeter. It has the characteristics of a cascade start-up and is the flow path of high and stable production. Energy increase by fracturing can effectively improve the flow capacity of pores and increase the imbibition displacement efficiency under the premise of good formation pressure retention. At the same time，fine pressure control can realize collaborative coupling of energy fields，which can further release the production capacity of shale oil reservoirs. The double pressure coordination of pressure retention and pressurization is the energy guarantee for high and stable production. The key development technology system guided by the theory of ternary-element storage and flow provides effective technical support for the production capacity breakthrough of multi-sag multilayer systems，which is of great significance for promoting the large-scale beneficial development of shale oil in continental faulted basins in eastern China.

Keywords

• faulted basins
• jiyang shale oil
• ternary-element storage and flow theory
• sweet spot evaluation
• development optimization
• balanced fracturing