Progress and development suggestions of deep normal pressure shale gas engineering technology

Abstract

Compared with the exploration and development of medium-shallow shale gas, deep shale gas is deeply buried, with complex structures and variable pressure systems, making it difficult to increase drilling speed. The reservoirs are of poor compressibility and it is difficult to transform the volume. How to improve drilling and completion efficiency and reduce drilling and completion costs is the largest challenge in achieving the economic benefits of deep shale gas development. In order to clarify the current technical level and existing problems of deep normal pressure shale gas drilling and completion, the technical indicators and progress of deep shale gas in drilling and completion engineering at home and abroad are summarized and analyzed in this paper and it points out the existing problems and puts forward suggestions. SINOPEC has realized the economic benefit development of deep normal pressure shale gas in blocks such as Weirong and Yongchuan and has basically formed a high-efficiency drilling technology system for long horizontal wells with low-cost high-performance oil-based drilling fluid, enhanced drilling parameters, high-torque positive displacement motor, personalized drill bit, precise guidance and efficient control of long horizontal wells, real-time drilling monitoring and intelligent optimization technology as the core. The maximum horizontal section length and one-trip footage have been extended to 4 386 m and 4 225 m respectively. However, compared with the advanced records in North America, there is still a certain gap between the life of positive displacement motor, stability and reliability of rotary steering tools, super one-trip drilling technology and ratio, and near-bit push tools. Therefore, it is necessary to research and develop the core tools to further improve the drilling efficiency. Due to the limitation of economic development benefits, the deve-lopment of deep shale gas in North America is less than 4 200 m. In China, we have broken through the 4 700 m deep shale gas fracturing technology and formed an independent 4 700 m deep shale gas fracturing technology system with fracturing technology, segmented tools, main materials, and monitoring technology as the core. However, for deep and ultra-deep shale in complex structural areas, it is difficult to form complex fracture nets. It is extremely necessary to further improve the fracture propagation mechanism, develop a fracturing fluid system with better drag reduction and 175 MPa fracturing equipment to break through the bottleneck of efficient fracturing technology for 4 700-6 000 m shale gas.

Keywords

• deep shale gas
• super one-trip drilling
• volume fracturing
• 175 mpa fracturing equipment