中江气田致密砂岩体积压裂应用

Volume Fracturing Application of Tight Sandstone in Zhongjiang Gas Field

四川盆地川西中江气田致密砂岩具有河道砂体展布不均、水平应力差大、脆性指数低、天然裂缝不发育、延伸压力梯度高的特点,前期施工压力较高排量偏低,使得改造整体加砂强度偏低,压后产量不理想。借鉴“流动距离最短,流动阻力最小,控制范围最大”理念,依托地质-工程一体化,以多向量强支撑体积改造为关键,研究川西致密砂岩体积改造工艺。基于均衡扩展精细布缝技术,优化川西致密砂岩双甜点分段分簇,大幅度增加横向动用率。以二级组合支撑、高排量连续加砂及变黏液体实时调控的强加砂技术,实现复杂裂缝耦合支撑剂组合的多向量强加砂。通过簇间多粒径暂堵球、缝内多组合暂堵剂的双重复合暂堵强制分流提高横向裂缝复杂程度。研究成果在川西中江气田已成功应用并逐步进行推广,加砂强度由前期0.50 t/m提高到4.18 t/m,加砂强度提高7倍多,已实施井平均无阻流量55.7×104 m^(3)/d,平均有效控制储量1.33×10^(8)m^(3),改造效果较前期显著提高。

The tight sandstone in Zhongjiang Gas Field in Western Sichuan has uneven distribution of channel sand bodies,large horizontal stress difference,low brittleness index,undeveloped natural fractures,and high extensional pressure gradient.The characteristics result in the low sand adding intensity of the transformation,high construction pressure,which makes the output after compaction is not ideal.This paper draws on the concept of“the shortest flow distance,the smallest flow resistance,and the largest control range”,relying on the integration of geology and engineering,with multi-vector strong support volume stimulation as the key makes a study on the volume stimulation technology of tight sandstone in Western Sichuan.Based on the balanced expansion of fine seam technology,the segmented clustering of tight sandstone double sweet spots in Western Sichuan is optimized,and the lateral production rate is greatly increased.With two-stage composite support,high-displacement continuous sand adding and real-time control of variable viscosity liquid,the high sanding strength technology realizes multivector forced sand with multi-fracture coupled proppant combination.The double compound temporary plugging and forced diversion of multi-particle size temporary plugging balls between clusters and multiple combined temporary plugging agents in fractures improves the complexity of transverse fractures.The research results have been successfully applied and gradually promoted in the Zhongjiang Gas Field.The research results have increased the sanding intensity from 0.50 t/m to 4.18 t/m in the early stage,increased by 8 times.The average unblocked flow rate has been implemented at 557000 cubic meters per day.EUR is 133 million cubic meters,and the transformation effect is significantly improved compared with the previous period.