高分子聚合物凝胶的性能研究与应用

传统的修井作业井筒内流体容易进入地层，造成储层的污染。针对储层的污染问题，以天然大分子纤维素为骨架分子，接枝共聚水溶性丙烯酰胺单体，研制出一种高分子聚合物凝胶，并对该聚合物凝胶进行机理分析和性能评价。结果表明，该聚合物凝胶的成胶时间在30～600 min可控，破胶时间在1～30 d；在160℃下表观黏度仅为100 mPaws，便于现场施工注入。通过加入交联剂和催化剂控制合理的成胶时间，成胶后的聚合物凝胶完全失去流动性，能够形成高强度的凝胶塞，具有较高的承压强度。聚合物凝胶具有较好的抗污性能，对强酸、强碱、高矿化度盐水以及原油污染能保持较强的稳定性。聚合物凝胶在施工结束后能够破胶为低黏度的流体，通过连续油管或者泥浆泵循环出井筒。该聚合物凝胶在威远区块204H7-3页岩气井的修井作业中进行了应用，在120℃、45 MPa下，80 m聚合物胶塞，最高承压达72.82 MPa。聚合物凝胶较传统机械封堵，及水泥塞封堵有比较明显的优势，在修井作业、恶性漏失、封堵出水层等方面具有较好的应用前景。 

Study on Performance of High Molecular Weight Polymer Gel and Its Application

In workover operations, wellbore fluids go into reservoir formations, resulting in formation damage. This problem can now be resolved with a high molecular weight polymer gel developed by grafting water soluble acrylamide onto the backbones of natural high molecular weight celluloses. Mechanism analyses and performance evaluation of the high molecular weight polymer gel showed that the gel time of the polymer gel is adjustable between 30 min and 600 min, and time for the gel to break is between 1 d and 30 d. The highest temperature at which the polymer gel functions normally is 160℃. Low apparent viscosity (100 mPa·s) renders the polymer gel good injectability. Using crosslinking agent and catalyst, the gel time can be controlled within a reasonable range, and the gelled polymer gel will lose its flowability, forming a high strength gel plug with high pressure bearing capacity. This polymer gel has good contamination resistance ability, and is resistant to contamination from strong acids, strong bases, saltwater of high salinity and crude oils. After operations, the polymer gel can be broken into low viscosity fluid which can then be circulated out of hole. Compared with conventional mechanical sealing and cement sealing methods, polymer gel has much better application prospects in well workover, lost circulation control and water kick control.