Well logging-based anti-drilling property evaluation of igneous rock in Bozhong 34-9 oilfield

The igneous rock of the Dongying Formation in the Bozhong 34-9 oilfield is found with a low average penetration rate and the drilling time-efficiency is severely impacted. Given this, this research investigated the rock mechanical properties of igneous rock. The rock mechanical properties of the igneous rock interval were calculated using the well logging data. The correlation between the anti-drilling property and interval transit time of sonic logging of the igneous rock in the study area was modeled in a mathematical-statistical approach, for evaluating the anti-drilling characteristics. Our research shows that the formation profile of anti-drilling characteristic parameters, based on well logging and rock properties, can truly represent the igneous rock in the study area. The prediction accuracy of the rock drillability, compressive strength, and shear strength reaches about 90%. Based on the above analysis, the bit and bottomhole assembly were optimized and then applied in several ten wells, which were found to increase the average penetration rate of the igneous rock by about 20%. The drilling rate and efficiency of the study area are effectively improved.