Objective In view of the serious problem of well leakage during drilling in high-temperature fractured oil reservoirs,the organic basic chromium cross-linked gel plugging agent was studied to plug the drilling leakage.Methods The rheological property,thermal stability,thickening property,breakthrough pressure gradient and plugging property of the gel plugging agent after core plugging were evaluated by viscosity test,high temperature aging test,thickening test and simulated plugging test.Results The experimental results showed that the apparent viscosity of the gel plugging agent was very low by using AM/AANa binary copolymer as base fluid,organic basic chromium OACrC-1 as cross-linking agent,and lactic acid as retarder before gelling.The thickness was less than 110 mPa·s.The thickening transition period was short,the agent showed right angle thickening property,and had good thermal stability at 120 ℃.The injection effect of gel plugging agent became better with the increase of fracture width within the experimental range.The core breakthrough pressure gradient and plugging performance showed that the gel plugging agent had good plugging performance for cores with different fracture width,and the plugging rate was more than 85.9％.Conclusions The gel plugging agent has good plugging performance in high-temperature fractured reservoirs,and its temperature resistance reaches 120 ℃.It has important application value and guiding significance in plugging lost circulation layer during drilling.
fractured oil reservoirsgel plugging agentright-angle thickeningperformance evaluationhigh temperature
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