Application of Digital Core Technology in Wellbore Stability Research

Abstract

Using core to conduct laboratory experiments is one of the important methods for wellbore stability research. However, as the objects of petroleum exploration gradually shift to areas with complex geological conditions, core acquisition is restricted by many problems, such as irregular shapes of cores obtained, low core acquisition rate, long construction time, and increasing operational cost. In recent years, exploration work in the southwest Tarim Basin has been further strengthened. Due to the complex strata and the frequent occurrence of complex well conditions during the drilling process, the problem of on-site coring has become more prominent, which seriously limits the analysis of rock properties. Therefore, scientific and effective cuttings analysis technology is urgently needed. This paper used digital core CT scanning technology to reconstruct the rock skeleton and its mineral facies using drill cuttings. The digital core was established, and the Poisson’s ratio and elastic modulus were calculated. The wellbore stability was analyzed, and the well sections, which were prone to wellbore instability, were determined. On this basis, KCl-polysulfonate drilling fluid was introduced. The influence of drilling fluid on rock strength was evaluated by digital core technology, and water immersion experiments were introduced to verify the experimental results. The results obtained by digital core CT scanning technology were compared with those obtained by triaxial compression experiments and well-logging data calculation, and the feasibility of digital core technology in the wellbore stability study and drilling fluid evaluation was verified.