A method of plugging the lost formation

Abstract

The present invention relates to a method for plugging lost formation, comprising: S10, bridging material plugging; S20, judging whether the plugging is successful; ~S60; S30, plugging while drilling and drilling through the lost formation; S40, controlling the ground squeezing pressure calculated by the pressure bearing capacity of the lost formation, and plugging the leakage with cement; S50, holding back the pressure and waiting for setting, and drilling through the cement plug; S60, The formation pressure bearing capacity test is carried out, and if the test fails, steps S40 to S50 are performed again until the formation pressure bearing capacity test is qualified. The invention can be used to guide drilling and plugging of lost formations, reduce operation risks, improve operation efficiency, and at the same time improve the pressure bearing capacity of lost formations, reduce the risk of repeated leakage, and ensure safe drilling.

Description

technical field [0001] The present invention relates to the technical field of drilling, and more particularly, to a method for plugging lost formations. Background technique [0002] In the process of offshore oil exploration and development, due to the needs of the wellbore trajectory, the drilling often encounters faults, limestone layers and other lost formations. After the lost circulation, it is difficult to plug the lost circulation. The possibility of re-leakage is extremely high. After re-leakage occurs, in order to drill safely, it is necessary to stop the leakage again, which will seriously affect the operation period and increase the operation cost. At the same time, due to the low pressure bearing capacity of the lost formation, during the drilling process after drilling through the lost formation, with the increase of drilling fluid density, the density of the equivalent drilling fluid exceeds the equivalent drilling fluid density of the pressure bearing capaci...

AI Technical Summary

Problems solved by technology

[0002] In the process of offshore oil exploration and development, due to the needs of the well trajectory, drilling often encounters lost formations such as faults and limestone layers. The possibility of re-leakage is very high. After re-leakage occurs, in order to drill safely, it is necessary to plug the leak again, which seriously affects the operation period and increases the operating cost.

At the same time, due to the low pressure bearing capacity of the lost formation, during the continuous drilling process after drilling through the lost formation, with the increase of the drilling fluid density, the equivalent drilling fluid density exceeds the equivalent drilling fluid density of the pressure bearing capacity of the lost formation, resulting in repeated leakage of the lost formation. Not only will it affect the operation schedule and cost, but in severe cases, it will also cause well control risks, formation collapse, pipe sticking accidents, and even wellbore scrapping

Images