Research on Combined Chemical and Physical Leakage Plugging Technology in Complex Leakage Formations in Bozhong Oilfield
The deep faults in Bozhong Oilfield developed,and the fracture openings are large,which belongs to the malignant loss with a very high loss rate.The plugging effect of the conventional plugging technology is not ideal,the pressure bearing capacity is weak,and the problem of repeated leakage occurs.Combining the advantages of chemical plugging and physical plugging,the combination of the two formed a composite plugging technology,which can effectively solve the problem of difficult plugging in malignant leakage formations.Experiments showed that the nanocomposite gel could maintain good rheological properties within 240 min,and the viscosity was controlled between 43 000 mPa·s and 35 000 mPa·s.The viscosity of the gel itself could also suspend the bridging plugging material very well,and the sedimentation ratio in 240 min was less than 20%.Compared with the single plugging technology,the composite plugging technology could achieve a good plugging effect for large cracks of 7 mm,and the pressure bearing capacity could reach 8 MPa.
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