Extended footage capabilities and high rate of penetration give PDC bits a distinct advantage over rollercone bits in many applications. However, the fixed PDC element creates an inherent limitation because only a small portion of the cutter contacts the formation, and as the cutters wear/chip drilling efficiency declines. The industry requires new technology that can effectively utilize the entire 360° diamond cutting edge to reduce frictional heat/wear while increasing drilling efficiency and bit life. A plan was initiated to rotate the cutter while drilling and engineers investigated different retention methods and cutting structure designs to create the optimal driving force to accomplish the objective. Several designs were implemented that hold the cutter securely in place and allow full cutter rotation. These assemblies were extensively modeled using FEA and laboratory tested to evaluate function and strength. In a test apparatus, the new shearing element (rolling cutter/RC) was able to cut an extended section of rock with a consistent force level (lbs). Conversely, the traditional fixed-cutter assembly required steadily increased force to drive the cutter the same distance. Examination of the rolling cutter's dull condition clearly indicated significantly improved durability and cutting efficiency. Initial field testing targeted the highly abrasive Granite Wash formation in Western Oklahoma/Texas Panhandle where cutter wear is the predominant failure mechanism. Application challenges include slow ROP and premature tripping for a new bit. A six-bladed prototype PDC bit was manufactured with three rolling cutters positioned in the shoulder area. The bit was run on a steerable motor through the horizontal interval with good results. The next prototype was equipped with additional RCs and drilled more footage compared to offset average. Additional experiments are being conducted with RCs which will continue to increase performance. The authors will present several case studies which will document performance improvement in challenging drilling environments.
Inconsistent roller cone/PDC bit performance drilling horizontally through the hard/abrasive Granite Wash reservoir in western Oklahoma has resulted in low ROP, increased operating days, and escalating drilling costs. The difficult Marmaton age wash formation is encountered at 11,000-13,000ft TVD and has unconfined compressive strength (UCS) in excess of 30,000 psi. The typical well requires drilling a curve to horizontal, then 4,000 ft of 6-1/8-in lateral borehole. Offsets analysis revealed that 1-4 RC/PDC bits are required to drill the curve in addition to 1-13 bits to finish the lateral. The operator required a technological solution to minimize bit consumption/trips to lower well construction costs while achieving directional requirements. An analysis of the most troublesome wells was conducted and a mathematical-based predictive analysis software identified the changes required to efficiently deliver the directional objectives. The study indicated that using a 4¾-in high-power steerable turbodrill, with two bends and a specific stabilization setup coupled with an application-specific 6 1/8-in diamond impregnated bit would significantly increase BHA performance and enhance section economics. The operator's drilling team studied the recommendation and concluded the BHA had the potential to increase reliability and reduce operating costs drilling the difficult Marmaton Wash. This new turbodrill/impregnated bit BHA was run in several Washita and Beckham County wells with outstanding results. In one well the BHA drilled 4,040ft of 6 1/8-in lateral hole section in a single-run saving the operator eight drilling days and $348,000USD vs plan. The assembly required steering only 17% of the time. The borehole was completed in 589hrs at an average ROP of 6.9ft/hr. This performance set several new world drilling records. The authors will present case histories that illustrate performance achievements in the horizontal section and provide details that contributed to the success of the unique BHA.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
customersupport@researchsolutions.com
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.