Pushing the Extended-Reach Envelope: Drilling a Record-Reach Well

Abstract

This article, written by Editorial Manager Adam Wilson, contains highlights of paper SPE 151046, ’Pushing the Extended-Reach Envelope at Sakhalin: An Operator's Experience Drilling a Record-Reach Well,’ by Michael W. Walker, SPE, ExxonMobil, prepared for the 2012 SPE/IADC Drilling Conference and Exhibition, San Diego, California, 6-8 March. The paper has not been peer reviewed. Extended-reach drilling (ERD) has become a common means to access reserves economically from existing infrastructure, provide access to reserves that were previously out of reach, and reduce the environmental footprint of drilling and production facilities. ExxonMobil, as operator for the Sakhalin 1 project, recently completed drilling operations at the Odoptu field, located offshore Sakhalin Island, Russia. The Odoptu development drilled nine extended-reach wells from shore, culminating with the world-record-reach OP-11. This record-setting extended-reach well reached a total depth of 12 345-m measured depth (MD) (40,502 ft) and 1784-m true vertical depth (TVD), with 11 479 m of vertical section in 60 days with less than 1% nonproductive time. Introduction The Sakhalin 1 project comprises the Chayvo, Odoptu, and Arkutun Dagi fields, located off the east coast of Sakhalin Island, Russia (Fig. 1). As of January 2011, 15 of the 20 longest-reach wells in the world had been drilled in the Sakhalin 1 project, with the Odoptu Well OP-11 surpassing the 2008 Maersk Well BD-04A in Qatar. Because of limited exploration-drilling data from the Odoptu field, the development was designed to be performed in stages. The first stage of development was designed to ascertain drilling and production performance, thereby allowing future development operations to be optimized. Hence, the project included drilling a vertical disposal well and seven ERD wells, with two additional ERD wells added subsequently. Following the drilling of a vertical cuttings-reinjection well, the first two ERD wells at Odoptu were designed to ascertain the height of the oil column, thereby refining the remaining drilling objectives. The first well, Well OP-8, drilled an 8½-in. pilot hole that penetrated the reservoir section horizontally in the oil column and was geosteered updip to locate the gas/oil contact, measure reservoir pressures (and determine fluid gradients), and exit the top of the reservoir again at a 99° inclination. The pilot hole was then plugged, and a horizontal production hole was drilled and completed. The second well, Well OP-7, was drilled downdip to determine the pressure and fluid gradient in the aquifer leg of the reservoir. It was subsequently sidetracked horizontally through the oil column and placed into production. Using the pressure and fluid-contact data from these two wells, the height of the oil column was deter-mined and vertical placement of subsequent wells in the reservoir sections was highgraded.