Analysis of geologic factors affecting wellbore stability of CBM horizontal wells

This paper intuitively describes the features of instability and collapse of coalbed horizontal wells by downhole measurement, analyzes the relation between the coalbed horizontal well stability and burial depth and coal sturdiness, and compares and analyzes the actual drainage data of the available CBM horizontal wells in Jincheng District. This paper identifies the main geologic factors affecting the CBM horizontal well stability as below: small and micro structures, ground stress and burial depth. The small and micro structures cause the horizontal hole to easily penetrate the soft coalbed, and ground stress and burial depth may increase the stress on the well wall and hence cause wellbore instability and collapse. The conclusions in this paper provide theoretical basis for preventing wellbore instability from geology.