Best Practice of Bit Optimization in a Strong Heterogeneity Conglomeratic Sandstone Reservoir: 8 Years Case History from Juggar Basin, West China

Abstract

MH oilfield, located in the Junggar Basin, in Xin Jiang Province of northwest China, is the world largest conglomerate reservoir with a fan-delta sedimentary environment. This long-term project can be traced back to 2012, and since then has gone through many technology revolutions and optimizations. At the end of 2017, the drilling performance of one main block inside MH oilfield, M18, was not optimistic when compared with other blocks. The extremely high formation hetergenity of the field made it very challenging to choose the right bit at the right time. This long-term project has brought to light the dedicated, quantifying study of the rock property differences throughout this field and inside each block. To solve this tough bit selection problem, geologic data was interpreted for engineering use. Two lines of data were processed. One was offset analysis based on the current run records to optimize bit designs, and the other was rock property interpretation and simulation to predict the formation variation, which covers the unconfined compressive strength (UCS), confined compressive strength (CCS) abrasion, impact simulations, layer correlations, statistical analysis and contour mappings of interest zones. This paper will summarize the field history, delineate the bit design lineage in this long-term project, and then mainly focus on geology simulations. The objective of this paper is bring to light the importance of CCS simulations to predict the bit performance and help the bit design and selection; provide a bit design lineage and bit optimization workflow for the drilling operation to optimize the inventory utilization and streamline the decision-making loop; provide a case study with coordinating multiple disciplinary teams to achieve specified objective; and provide a concept of integration of geology and engineering in the