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A New Dynamic Fracture Plugging Evaluation Method and Its Application in Cementation for Mudstone and Sandstone Formation with Narrow Pressure Range in China South Sea

One of the difficulties in high temperature and high pressure wells and deepwater well cementation in China South Sea is that the pressure range is very narrow. In the drilling or cementation process, the formation is easy to form sharp crack leakage. In general, the traditional simulation of bottom-hole mud or cement slurry leakage is to use the mesh plate or fixed width at a certain temperature and pressure difference. However, when there are wedge cracks in the formation, it will cause repeated "huff and puff" dynamic leakage of fluids. Dynamic leakage puts forward higher requirements for evaluation methods and plugging materials. In view of the problems, a new dynamic fracture plugging evaluation instrument was developed, and the new hydraulic wedge plugging material and matching cementing technology were optimized, which solved the problem of cement slurry leakage and return in China South Sea. The results of this paper have been successfully applied in cementing operations of high temperature and pressure wells and deepwater wells in the China South Sea, effectively solving the problem of hydraulic wedge leakage in sandstone formation cementing with narrow safety pressure window.