NEWS FROM SPE/IADC 2013: Drilling time, cost issues solved in Granite Wash of Oklahoma
BY KURT ABRAHAM, Executive Editor
AMSTERDAM -- A technical paper presentation at the SPE/IADC Drilling Conference in Amsterdam described how Apache Corp. and Schlumberger solved bit performance problems that had hampered drilling efficiency. As described by Apache’s Chris Jamerson, inconsistent roller cone/PDC bit performance, drilling through the hard/abrasive Granite Wash reservoir in western Oklahoma had resulted in low ROP, increased operating days and escalating drill costs. Apache had encountered the difficult Marmaton wash at about 11,000-13,000-ft TVD, where unconfined compressive strength (UCS) was 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. An offsets analysis had revealed that one to four RC/PDC bits were required to drill the curve, in addition to one to 13 bits to finish the lateral. Apache required a technological solution to minimize bit consumption and trips, to lower well construction costs while still achieving directional requirements.
Jamerson said Apache and Schlumberger conducted an analysis of the most troublesome wells, and used mathematically based, predictive analysis software to identify the changes need to efficiently deliver the directional objectives. Results indicated that using a 4 ¾-in. high-power, steerable turbodrill, with two bends and a specific stabilization set-up, paired with an application-specific 6 1/8-in., diamond-impregnated bit, would raise BHA performance significantly and improve section economics. Apache’s drilling team studied the proposed solution and agreed that it should work.
The new turbodrill/impregnated bit BHA was run in several Marmaton wells with noticeably better results, said Jamerson. In one well, the BHA drilled 4,040 ft of 6 1/8-in. of lateral hole section in a single run, saving Apache eight drilling days and $348,000 vs. plan. Also, the assembly required steering only 17% of the time. The borehole was completed in 589 hr at an average ROP of 6.9 ft/hr. Apache and Schlumberger claim that this performance set several new world drilling records.