球状凝胶复合封堵剂的研制与应用

为解决涪陵地区页岩气储层层理、裂缝发育导致的油基钻井液漏失严重的问题,通过分析页岩气地质特征及油基钻井液特性,研制出纳微米级可变形球状凝胶,辅配优选出的片状、纤维状封堵材料,合成了球状凝胶复合封堵剂。室内评价表明,在油基钻井液中加入2.4%球状凝胶复合封堵剂后,高温高压滤饼厚度由4.0 mm减小至1.5 mm,高温高压滤饼渗透率降低97.66%,20/40目石英砂床封堵承压能力由2 MPa提高至17 MPa。该球状凝胶复合封堵剂在涪陵地区66口井的现场应用结果表明,其与油基钻井液的配伍性好,可随钻封堵微孔、微裂缝,防止或减少钻井液漏失,从而有效降低油基钻井液的钻进损耗。 

The Development and Application of a Microsphere Gel Composite Plugging Agents

During drilling shale gas wells in the Fuling Area, the oil-based drilling fluid is often lost seriously due to bedding and developed fractures. To address this problem, a nano-micron deformable spherical gel was developed after the geological characteristics of shale gas and properties of oil based drilling fluid were analyzed, and sheet or fibrous plugging materials were selected additionally to form the composite microsphere gel plugging agent on the basis of compatibility and sealing performance evaluation. Laboratory evaluation showed that the thickness of mud cake at high temperature and high pressure (HTHP) decreased from 4.0 mm to 1.5 mm, permeability reduced by 97.66%, and the pressure-bearing capacity of quartz sand bed (20 to 40 mesh) increased from 2 MPa to 17 MPa after adding microsphere gel plugging agent by 2.4% into oil based drilling fluids. This agent was applied to 66 wells in Fuling Area, and the results indicated that composite microsphere gel plugging agent was well compatible with oil-based drilling fluids, and it can prevent or reduce the loss of drilling fluid by plugging micropores and microfractures in drilling operation, so as to decrease the loss of oil based drilling fluids effectively.