Plugging technology optimization of coalbed methane infill well in mature block
In order to solve the problem of lost circulation during infill drilling in mature blocks of the Qinshui Basin,a 3D well bore fracture model was developed based on the study of the actual well bore structure in the blocks,Ansys-Fluent software was used to simulate the flow of conventional plugging,pressurized plugging,gel plugging in formation fractures,and the simulation results were verified in field construction.The results show that,the time of plugging ranks as:gel plugging<pressure plugging<conventional plugging;the return height of cementing annulus cement ranks as:gel plugging>pressure plugging>conventional plugging.Combining with the advantages and disadvantages of the three lost circulation techniques,it is shown that the effect of gel plugging is better if a single point loss occurs and the lost circulation location is clear;if it is a multi-points leakage,and the leakage location is not clear,then the pressurized plugging is better.In addition,compared with the conventional static plugging technology,the optimized plugging technology combining with wellhead pressure technology has the advantages of less plugging time,higher pressure bearing capacity of the lost formation and better plugging effect,and the required pressure bearing equipment is easy to make on the spot,which is of simple operation and stronger applicability.
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