一种耐高温交联淀粉钻井液降滤失剂的制备与评价

针对常规钻井液降滤失剂耐高温性能不足的缺点，以玉米淀粉为原料，以三偏磷酸钠为交联剂，采用交联反应的方法，合成了一种耐高温的交联淀粉钻井液降滤失剂，并采用六速旋转黏度计、泥浆失水测定仪等设备评价其性能。实验结果表明：采用三偏磷酸钠为交联剂制备的交联淀粉具有良好的耐温性能，当钻井液中交联淀粉质量分数为1.5%时，在160℃的条件下仍具有较好的降滤失性能，API滤失量为11.0 mL,黏度为33.5 mPa·s,与羧甲基淀粉降滤失剂相比，该降滤失剂抗高温效果明显，且不增黏。在西南油田元坝区块某评价井应用结果表明，在150℃条件下有效降低了钻井液的滤失量，同时控制了钻井液黏度，提高了钻井液整体耐温性能，现场应用效果良好。该研究成果对交联淀粉钻井液降滤失剂的制备具有一定的参考价值。

Preparation and Application of Cross-linked Starch as Filtrate Reducer with High Temperature Tolerance for Drilling Fluid

In view of the poor high-temperature tolerance of conventional filtrate reducers for drilling fluid, a cross-linked starch as filtrate reducer with high temperature tolerance for drilling fluid was synthesized by cross-linking reaction method with corn starch taken as raw material and sodium trimetaphosphate as cross-linking agent. As found in the test results, the cross-linked starch prepared by using sodium trimetaphosphate as the cross-linking agent was highly tolerant to temperature; when the mass fraction of cross-linked starch in the drilling fluid was 1.5%, it was still effective in filtrate loss reduction at 160 ℃, with an API filtrate loss of 11.0 mL and a viscosity of 33.5 mPa·s; compared with carboxymethyl starch used as filtrate reducer, this filtrate reducer was distinctly effective in high temperature tolerance without viscosity increase. The results of its application on an appraisal well in Yuanba Block of Southwest Oilfield showed that it effectively reduced the filtrate loss of drilling fluid at 150 ℃, and at the same time controlled the drilling fluid viscosity and improved the overall temperature tolerance of the drilling fluid. The field application effect was excellent. The results of the study can serve as references for the preparation of cross-linked starch as filtrate reducer for drilling fluid.