苏里格深部煤系致密气储层绒囊流体控水压裂

Applying fuzzy-ball fluid to the water control fracturing in deep coal-measure tight gas reservoirs in Sulige

苏里格深部煤系致密气储层厚度较小,压裂过程中易沟通水层致使气井产水,因此在压裂深部煤系致密气藏同时需要实施控水。利用封堵性绒囊流体进行控水压裂,既可以提高产量又可以减少出水。对室内配制的绒囊流体开展评价实验,将绒囊流体分别与前置液、地层水等体积混合测试其配伍性,然后利用岩心驱替装置测试气、水突破绒囊封堵岩心基质和造缝岩心柱塞的突破压力,表征绒囊的增气堵水性能。发现绒囊流体与前置液和地层水分别混合后无沉淀生成,绒囊流体封堵含裂缝岩心的气、水的突破压力梯度分别为0.02 MPa/cm、0.04 MPa/cm,绒囊流体封堵基质岩心的气、水的突破压力梯度分别为0.03 MPa/cm和0.2 MPa/cm,皆满足现场施工要求。在苏里格气田A、B两井实施控水压裂,两井在注入前置液造缝后分别泵入50 m3绒囊流体进行堵水,控水压裂后对比同层邻井161 d内平均日产量分别提高了13.71%和6.99%,邻井C、D两井分别泡排3次、63次,而A和B两井投产后无积液产生。研究认为利用绒囊流体在深部煤系致密气层进行控水压裂可以实现增气减水。

The reservoirs of the deep coal-measure tight gas reservoirs in Sulige are thinner,so water layers can be connected easily in the process of fracturing,which leads to water production of gas wells.Therefore,it is necessary to carry out water control while the deep coal-measure tight gas reservoirs are fractured.In this paper,the plugging fuzzy-ball fluid was used for water control fracturing,which can improve the gas production while reducing the water production.Evaluation experiments were conducted on the fuzzy-ball fluid prepared in the laboratory.The fuzzy-ball fluid was mixed with preflush fluid and formation water respectively in the equal volume to test its compatibility.Then,the pressure of gas and water to break through the fuzzy-ball plugged matrix core and fracturing core plunger was measured by using the core displacement device,so as to characterize the ability of fuzzy ball to increase gas production and plug water.It is shown that no settlement is formed after fuzzy-ball fluid is mixed with preflush fluid and formation water respectively and the breakthrough pressure gradient of gas and water is 0.02 MPa/cm and 0.04 MPa/cm respectively in the fracture-containing core plugged with fuzzy-ball fluid and 0.03 MPa/cm and 0.2 MPa/cm respectively in the matrix core plugged with fuzzy-ball fluid,all of which meet the requirements of field construction.Water control fracturing is carried out in Well A and B of Sulige Gas Field.After preflush fluid is injected into both wells for fracturing,50 m3 fuzzy-ball fluid is pumped to plug water.And compared with the neighboring wells in the same layer,average daily production within 161 days of Well A and B is 13.71%and 6.99%higher respectively after water control fracturing.Foam drainage is carried out 3 times and 63 times respectively in the neighboring wells(C and D),but no liquid loading occurs in Well A and B after they are put into production.In conclusion,applying fuzzy-ball fluid to the water control fracturing in deep coal-measure tight gas reservoirs can realize gas production increase and water production reduction.