Cavings’ role in representing the type of wellbore failures in fractured reservoirs

Analyzing wellbore stability is a key component in awell-drilling plan. Therefore, identifying the parameters which leadto understanding the wellbore failure is very important. Cavings anddrill cuttings are useful sources that give very great informationabout the wellbore condition, lithology, etc. Also, by analyzingcuttings and cavings, recognizing the failure type, wellboregeometry, and formation pressure might be more likely. The mostimportant parameters which affect the wellbore instability aredivided into three groups including (i) mechanical parameters of thewellbore and the formation (e.g., state of in-situ stresses, rockstrength), (ii) chemical effects, and (iii) the drilling fluid. In case oflacking the well-logging data such as caliper, image logs, or LWD(logging-while-drilling), analyzing cavings is a very effectiveapproach to identify the failure reason. Different phenomena likeexisting natural fractures or weak planes, in-situ stresses, anddrilling procedures may lead to the production of cavings. Thispaper aims to present the cavings’ role in demonstrating thewellbore failures and discusses causes, indicators, and diagnosing ofwellbore instability. Meanwhile, the paper describes the role of theMechanical earth model (MEM) in predicting and preventingwellbore failure.

کلیدواژه ها:

Cavings ، Mechanical Earth Model ، Wellbore Stability ، Safe Mud Weight Window