An Innovative Design for Drillstring Testbed for High Pressure High Temperature Drilling

Abstract In this paper, a novel design for a full-scale, industrial-size, and high pressure high temperature (HPHT) drillstring test rig is presented. The test more accurately replicates the downhole environment with regards to bit performance limiters. The facility has a high-power drill string with side loading, reasonably sized mud pumps, a HPHT sample that generates a hot pressurized rock-bit interface and the ability to easily replicate specific drilling scenarios. This provides a step change in drilling research. Replicating down-hole HPHT conditions in a surface level drilling test rig is challenging but will deliver significant benefits for downhole tool and instrument development. The proposed test rig will provide these test conditions for developing longer lasting and more efficient bits, more effective drilling fluids, and lower friction tool joints to increase weight on bit (WOB) and rate of penetration (ROP). A secondary benefit is for identification of bit-rock interaction laws that will assist in implementing successful automated drilling (AD) approaches to reduce drillstring and bit failures from stick-slip, bit-bounce and other drilling anomalies. AD has the potential for increasing efficiency as well as reliability of drilling. The force and torque laws will also be utilized in drillstring dynamics simulation software for operator training and hardware development. The proposed test rig gives the industry a unique opportunity to couple experimental work that is representative of downhole conditions with actual industry problems and concerns. By using data sets from actual drilling operations, we will be able to replicate what is occurring downhole but in a controlled, measurable environment on the surface. The system will be highly automated with a remotely operated control room, to increase safety in the high temperature, pressure, force and torque environment of the test rig. The system is to be fully enclosed with an API rated pressure containment system. The description of the test rig here is intended to convey the complexity of the hardware needed to meet functionality requirements and operating conditions. The design is purposely configured to accommodate the inevitable small requirement modifications, with minimal delays in rig completion.