致密气藏非均质水平井分段压裂关键技术

Staged Fracturing of Heterogeneous Horizontal Wells in Tight Gas Reservoir

MS地区蓬莱镇组气藏属于致密砂岩气藏，非均质性强，水锁伤害严重，多数井砂泥岩交互。针对水平并分段压裂布缝难度大，压裂液储层适应性差，压后效果差等难题，研究形成了考虑启动压力梯度的基于独立渗流单元的裂缝间距优化技术；优化出低伤害防水锁压裂液体系，残渣含量下降了17％-20％，润湿接触角从39.9°提高至91.5°，水锁伤害后气测渗透率恢复率从33.1％提高至71.98％；研究了液氮增能及伴注工艺，现场试验7口井，施工成功率100％，有效率100％，压后平均测试产量3.617×10^4m^3／d，是前期分段压裂的2.2倍，平均返排率为68.3％，较前期提高了17.4％。

In MS area, the Penglaizhen Formation is a tight sandstone gas reservoir, which is characterized by strong heterogeneity, severe water- locking damage, and sandstone mostly interbedded with mudstone. There are some problems existing in horizontal-well staged fracturing, including large difficulty in fracture deployment, fracturing fluid poorly available for reservoir, and disappointing effect after fracturing. So, considered starting pressure gradient, a technology is presented to optimize fracture space based on independent percolating unit. A fracturing-fluid system with low damage and water-locking prevention is optimized. And after this optimization, residual content fell 17 %~20 %, wetting contact angle increased from 39.9 ° to 91.5 °, permeability recovery rate raised to 71.98 % from 33.1 %. Some techniques of both liquid N2 energization and accompanying injection are developed. And after their application to 7 wells, operational success rate and efficient factor achieved 100%; average testing production after fracturing was 3.617×104m3/d, 2.2 times of that at the early staged fracturing; average flowback rate was 68.3 %, increasing by 17.4 %, respectively.