不动管柱多层分层加砂压裂技术及其应用

针对川西中浅层气藏低渗低孔，纵向上多层系、多砂体叠置等特点，开发了不动管柱多层分层加砂压裂工艺。确定了适应不同储层温度的低伤害压裂液配方，各配方低伤害压裂液均具有较好的抗剪切性能，对岩心伤害率仅4％～12％；不动管柱多层分层加砂压裂工艺可一次性完成三层甚至四层分层压裂，其配套低密度钢球及捕球工艺可大大减少因钢球留在井内对天然气产量和后期作业的影响。该技术现场应用于三层或四层分层13井次，单井平均加砂量92．5m^3，返排率均达62％以上，低密度钢球捕获率72．4％，压裂前平均天然气产量0．3529×10^4m^3／d，压裂后平均天然气产量11．6698×10^4m^3／d，增产效果显著。该技术为同类气藏的高效开发提供了依据，具有较好的推广应用前景。

Immobile String Multiple Separate Layers Sand Fracturing Technology and Its Application

In view of the characteristics like low permeability, low porosity, multi - layer system and superimposition in longitudinal direction of the shallow to middle layers gas reservoir in western Sichuan, an immobile string multiple separate layers sand fracturing technology was developed. The low damage fracturing fluid formulations suitable for the temperatures of different reservoirs were identified. Each of the low damage fracturing fluid formulations has exhibited good shear resistance performance with the core damage rate of only 4% to 12%, that is only half or less of that of conventional fracturing fluid. Three or four separate layers fracturing can be accomplished one time with the immobile string multiple separate layers sand fracturing technology, and the influence of the retention of steel balls in wells on natural gas production rate and subsequent operation can be minimized by making use of the auxiliary low density steel balls and the ball catching technology. This technology has been applied in field to three layers or four layers fracturing for 13 times. The average sand filling volume of one single well was 92.5 m^3, the flowback rate was more than 62%, and the low density steel balls capture rate was 72.4%. The average natural gas production rate before fracturing was 0. 352 9 × 10^4 m^3, and that after fracturing was 11. 669 8 × 10^4 m^3, showing that the production increase was significant. This technology is preferable for the effective development of the gas reservoir of the same kind, and has a bright future of promotion and application.