Shaped Cutter Performance Optimization Through Advanced Drilling Simulations

Abstract

Historically polycrystalline diamond compact cutters have consisted of a planar cutting face on a cylindrical diamond table. For decades industry has been aware of the potential drilling performance gains from forming these cylindrical cutters into other geometrical shapes. These early generation shaped cutters did not gain traction due to limitations in diamond technology, and high manufacturing costs associated with shaping the cutters. Recently PDC drill bits with shaped cutter designs are becoming more prolific in worldwide drilling applications. Often, the novelty in the design of the cutter shapes is enticing enough to merit opportunities for field runs. However, without an informed understanding of shaped cutter behaviors, there is risk of diminished drilling performance if the cutter shapes are not applied properly to the bit and application. The objective of this paper is to develop methods to evaluate two critical behaviors for shaped PDC cutter designs, overload integrity and aggressivity, and apply these methods to a full bit drilling model. The cutter overload integrity characterization methods are developed using finite element analysis and the aggressivity characterization is based on high pressure visual single point cutter laboratory test data. The information is fed into a full bit drilling numerical model to predict bit performance and ability to avoid cutter breakage in a simulated drilling environment, accounting for factors such as lithology, interbedded transitions, bottom hole assembly type, and operating parameters. The models enable optimization of shaped cutter design and fit for purpose cutter selection. The full bit model is tested and validated against field runs. Case studies include interbedded drilling in the Haynesville and Permian Basins. In both applications, bits were run with different shaped cutter designs, using drilling performance and dull photos to compare to the model outputs. ROP gains of 35% were seen in the Haynesville application, while the cutter survival rate more than doubled in the Permian application by using optimally selected shaped cutters. The methods presented in this paper provide new pathways for shaped cutter design and selection. Digital tools are demonstrated to perform the multi-faceted analysis efficiently for pre-well planning and post-run analysis.

Modeling and Investigation of the Velocity-Dependent Cutting Process with PDC Cutters Using the Discrete Element Method

“…To characterize the rate dependency in the rock cutting process, single cutter tests under hydrostatic confning pressure were conducted on a test rig [22]. Te test rig mainly consists of a pressure vessel and a cutter shaft.…”