Application of Conformal Coring Tool in Complex Formation of Block Structure

Due to complex geological structure, strong formation heterogeneity, intermixed sand mudstone in H6 block of eastern oil field, which caused low core recovery. To solve this problem, new conformal core drilling tool which is suitable for fault block oil reservoir is designed. First, the shape of drill bit crown and the way of tooth arrangement are changed. Furthermore, we replace the inner tube with aluminum alloy tube, set the core measures and optimize the drilling parameters. The result shows that the number of bit crown blade is decreased from 10 to 8 and size of cutting teeth is decreased from Ф13 to Ф10 mm, which increases cutting efficiency and drilling rate in coring section. The application of aluminum alloy inner tube and conformable coring technology overcome the problem of inhomogeneity of borehole and lithology inequality. Finally, the core recovery is increased from 54.43 to 80.97%. It proves that the new coring tool can effectively improve core recovery in complex fault block formation and open a new way for coring in deep well of complex geological structure.