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裂缝—孔隙型致密砂岩气藏具有低孔低渗、高毛管压力、裂缝发育、水湿性、高束缚水饱和度等地质特征。在钻井完井、增产改造及气藏开发过程中,滤液和边底水等侵入会导致气井近井地带含水饱和度上升,气相渗透率下降,致使发生水相圈闭损害。针对裂缝—孔隙型致密砂岩气藏的地质特征,对裂缝—孔隙网络系统在钻井和开发过程中不同的水相圈闭损害模式进行了研究,探讨了基块和裂缝系统中工作液和边底水侵入导致水相圈闭损害的形成过程和损害机理,提出在钻井、完井、修井、增产改造及开采过程中,通过屏蔽暂堵及欠平衡等技术减少工作液侵入量、优化工作液、增大返排压差、减少界面张力、蒸发或加热降低含水饱和度以及排水采气、均衡开发等措施防治水相圈闭损害。
Fracture-pore type tight sandstone gas reservoirs have such features as low porosity and low permeability, high capillary pressure, fracture development, water wettability and high irreducible water saturation. In drilling and completion, stimulation and gas reservoir development, the intrusion of filtrate and edge-bottom water will lead to the increase of water saturation near gas well and the decrease of gas permeability, resulting in water phase trapping damage. In view of the geological characteristics of fractured-porosity tight sandstone gas reservoirs, the different trap modes of water-phase traps in the fracture-pore network system during drilling and development are studied. The influences of working fluid and edge Water intrusion leads to the formation process and damage mechanism of water phase trapping damage. It is proposed to reduce the intrusion of working fluid through technologies such as shielding temporary blockage and underbalanced during drilling, completion, workover, stimulation and recovery, and optimize working fluid , Increase the backpressure, reduce the interfacial tension, evaporation or heating to reduce water saturation and drainage gas, balanced development and other measures to prevent and control water traps damage.