Real-Time Development of New Technology Saves Operator U.S. $5.1 Million

Abstract

This article, written by Assistant Technology Editor Karen Bybee, contains highlights of paper SPE 91862, “Real-Time Development of New Technology Saves Operator $5.1 Million Drilling Deep Exploration Well, Colombia,” by Andrew Frazelle, SPE, and Reynaldo Vargas, SPE, BP plc; Raul Krasuk, SPE, Baker Hughes Oasis; and MacLean Price, SPE, Hughes Christensen, prepared for the 2005 SPE/IADC Drilling Conference, Amsterdam, 23–25 February. A vertical well had never been completed successfully in the Llanos foothills of Colombia. On the basis of the success of this type of well in Argentina, the operator requested the technical assistance of a drilling-optimization service. The operator and service company developed a flexible, yet detailed, strategy to address the anticipated challenges. Because of slower than forecast penetration rates using conventional bit technology, the operator and ser-vice company decided to build a new-style diamond-impregnated bit that had been discussed during the planning phase. The resulting 14¾-in. impregnated Intl. Assn. of Drilling Contractors (IADC) M842 set a new world single-run-footage record drilling 499 ft at 3.9 ft/hr. Introduction The Niscota E-1 exploration well (30 km from nearest production) was a critical prospect for BP and the Colombian petroleum industry. The Niscota prospect is in the northeast part of Colombia on the most productive trend in the country. The project was a major exploratory effort and presented the operator with a number of distinctive challenges including high geological uncertainty, first well in the structure, dip angle greater than 65°, and highly abrasive formations. Because of the mountainous nature of the Andes foothills, options for surface location were extremely limited. This increased well-bore complexity because engineers could not use the “natural drift” strategy where the sur-face location is offset from the target and the bottomhole assembly (BHA) is permitted to drift updip to the target reservoir. Unlike previous BP operations in the region, the Niscota wellbore would have to be near vertical. Implementing Solutions To address the vertical-hole-section challenge, the operator elected to use a vertical drilling system (VDS) that has solved similar challenges in Argentina. The major components include a high-torque power section, the control subassembly, and the pulser housing. The VDS tool is an individual closed-loop system with the option of two-way communication with the driller at surface. Three hydraulically controlled spring-loaded steering ribs are positioned at the upper bearing housing approximately 2 ft behind the bit. The short distance to the bit and the ability to control each rib individually keeps the BHA on its desired vertical path. To maintain a near-vertical well path in this challenging drilling environment, the VDS can apply as much as 6,600 lbf of side force against the borehole wall. A continuous steering process minimizes local doglegs, resulting in a high-quality in-gauge wellbore. The VDS mainly is operated without rotating the drillstring. This lack of drillstring rotation reduces the power available at the bit. To compensate for this power loss, the VDS downhole motor features a precontoured steel stator tube. This technology enables the tool to generate as much as 50 to 100% more power than conventional existing stators.