Remotely Operated Guideposts Reduce Drilling Time and Costs

Abstract

Summary Remotely operated guideposts were successfully used to establish, release, and re-establish guidelines for a template installation in 1,758 ft [536 m] ofwater in the Gulf of Mexico. The guideposts were used to reduce thedrilling-template weight, to improve accessibility of the remotely operatedvehicle (ROV) around the well slots, and to reposition the blowout preventer(BOP) stack on a new well without tripping the stack to the surface. Beforefield installation, procedures were developed and the guideposts and runningtools were function tested. Wet tests verified the reliability of the ROV andguidepost interface. This testing contributed to the successful use ofguideposts. Drilling-template costs dropped significantly. The approach helpedsave about 36 days of drilling time. The guideposts were also used to tie backthe tendons and production risers for the tension-leg well production risersfor the tension-leg well platform (TLWP). platform (TLWP). Introduction The Jolliet Project has been under development since June 1987 in 1,758 ft[536 m] of water in Green Canyon Block 184 of the Gulf of Mexico. Drillingthrough a template in this depth requires safe, cost-effective subsea-guidelineanchoring techniques. Therefore, guideposts and associated equipment weredesigned to be used with an unmanned ROV. The guideposts were used to install the template well pod and to positionthe BOP stack (Fig. 1). Because of the importance of reliable procedures andequipment, especially in a deepwater environment, contingency planning wasemphasized. This included operational testing before field use. This paper discusses objectives for guidepost use, the remotely installedguidepost, guidepost running tools, and equipment testing. It also presentsfield performance results, conclusions, and performance results, conclusions, and recommendations for future applications. Objective and Results Use of removable guideposts improved drilling-template design and optimizedprocedures. The elimination of permanent procedures. The elimination ofpermanent guideposts reduced the template weight and decreased the materialcosts because only four primary and four backup guideposts were required. Italso provided an uncluttered template work area. This increased the ROV'spossible work scope while reducing the complexity of its operations. Procedures that allowed the BOP stack to be kept on bottom for 90 days bymoving from well to well were simplified by a topaccess guidepost design. Stackrepositioning, including raising and relatching, was completed in about 9hours, which saved 1.8 days/well. With minor modifications, the guideposts were also used to optimize twoother operations (Fig. 2). When the production riser is run, special shearbolts that break with a reduced tensile load on the guidepost are used. Toassist in the installation of the tendons for the TLWP, the guidepost wasfitted with an outer sleeve that has a sheave Fig. 3). Equipment Guideposts. Skeels and Landeis described the design of the remotely operatedguidepost (Fig. 4). The post has an 8.62-in. [219-mm] -diameter outer body witha latching profile on top and a landing ring near the bottom that lands in thefunnel receptacles on the template. Two spring-loaded, outwardly biased latchdogs at the bottom of the post anchor the guidepost to the receptacle. Theguidepost has an inner sleeve and cam mechanism so that a top-access tool canretract the latch dogs and release the post. A backup release mode is providedby four shear bolts. The tensile force to shear the bolts is applied byattaching a strong wire rope to the guidepost or latching onto the guidepostwith a steel drillpipe tool. Tools. Two types of guidepost tools can be used to release a guidepost fromits funnel receptacle. Both types have a collet that slips over the latchingprofile at the top of a post. Hydraulic cylinders in the tool move a ring downover the collet to lock the tool to the post (Fig. 5). Continued movement ofthe post (Fig. 5). Continued movement of the ring depresses the guidepost innersleeve, which causes the cam mechanism in the guidepost to retract the latchdogs for release of the post from its funnel receptacle. The steel version of the tool is run on drillpipe with two hydraulic linesconnecting it to a 3,000-psi [21-MPa] hydraulic pump on the rig. TheROV-compatible version of the tool was made for this project by usinglightweight materials and adding flotation elements. The ROV positions the tooland then supplies the hydraulics to operate it. Ancillary tools, such as guideframes and remote cable anchors, allowflexibility in procedures. To re-establish a guideline, for procedures. Tore-establish a guideline, for example, the remote cable anchor can be latchedto a guidepost with the guidepost tool. Equipment Testing Guideposts and tools of this basic design were developed and tested in 1985and successfully used in 1,400 ft [427 m] of water in the Gulf of Mexico. Additional testing was needed for the Jolliet Project because of the concernfor ROV dependability and use of prototype ROV tool designs. P. 272