Connector/Conductor Wells: Multiple Wellbores With Downhole Connections

Abstract

This article, written by Technology Editor Dennis Denney, contains highlights of paper SPE 111441, "Connector-/ Conductor-Wells Technology in Brunei Shell Petroleum Achieve High Profitability Through Multiwellbores and Downhole Connections," by Shaikhan Al- Khodhori, SPE, Petroleum Development Oman; Hamoud Al-Riyami and Philip Holweg, SPE, Brunei Shell Petroleum; and John Wright, SPE, John Wright Company, prepared for the 2008 IADC/SPE Drilling Conference, Orlando, Florida, 4-6 March. The paper has not been peer reviewed. Connector/conductor (CC) wells were implemented in Brunei. The conductors (feeders) are horizontal wellbores drilled through the oil rims, with the section of the wellbore above the top of the reservoir abandoned. These conductor wellbores act as horizontal flow conduits in the reservoir. Production to the surface is through dedicated connector (producer) wells designed to connect several conductor wellbores and provide shared completion equipment to surface. Success of the Darat CC-wells project proved technically feasible for implementation in other fields. Introduction The Champion West field has several oil rims that are displaced vertically and laterally from each other. The volumes in these rims are too small to justify a dedicated producing well for each rim. The CC-well concept shown in Fig. 1 was proposed to develop these marginal oil rims. Also, it was recommended that the concept be proved further in the Darat asset before full implementation in the Champion West field because Darat is a lower-cost environment, has less-complicated subsurface features compared with Champion West, and has existing suspended exploration wells for intersection and connection. Fig. 2 shows the plan for the Darat CC well, where Well S-840 is a land well acting as the connector and Well S-833 is an offshore well acting as the conductor. Well S-833 was drilled at the end of 2005 and completed in November 2006, with two gravel-packed completion zones. The Darat CC well was to prove the following.The ability to "home in" and achieve a close proximity with the existing well of less than 40 cm at approximately 90° incidence angle without a plugback.The ability to connect the two wells (conductor and connector) mechanically and hydraulically and sustain sufficient flow through the connection. Two technical challenges or key technology areas that were critical for success were improving ranging accuracy and making a hydraulic connection between the two wellbores. Technical Solutions Homing-in and Bypass Strategy. Borehole-surveying instruments [e.g., measurement-while-drilling (MWD) and gyro technology] do not have sufficient accuracy to achieve the required trajectory and proximity to make a perforated connection. To close this gap, homing-in or ranging technology would be required. Two techniques were selected: single-wire guidance sys-tem (SWGS) and rotating-magnet ranging system (RMRS).