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Technical Paper: Geo-Stopping Using Deep Directional Resistivity LWD

Society: SPE
Paper Number: 173169
Presentation Date: 2015
 Download: Technical Paper: Geo-Stopping Using Deep Directional Resistivity LWD (2.26 MB PDF) Login | Register

 

Abstract

The Wheatstone LNG Project in Western Australia utilizes subsea big-bore gas wells for producing the Wheatstone and Iago gas accumulations. These wells employ a 9-5/8" production conduit from the top of the gas pay zone to the ocean floor to maximize their productive capacity. A critical design requirement is that the 9-5/8" production conduit must be set as close as possible to the gas pay zone (i.e., within 3m or less) without actually penetrating into the productive core of the gas zone. The wells must also intersect the horizontal top of the gas zones at inclinations (inc) of 45-60°. these design requirements impose a significant challenge for the efficient execution of a Wheatsone well. Traditional "ahead-of-the=bit" logging-while-drilling (LWD) solutions are capable of detecting resistivity fluctuations up to 1m in front of the drill bit. This, however, was considered and insufficient look-ahead distance to prevent premature penetration of the gas reservoir. Alternative solutions, such as pilot holes and biostratigraphic analysis of drilled cuttings, were also considered but fond to be either too expensive and/or operationally impractical.

During and exhaustive search for a potential solution to this dilemma, Wheatstone Project team reviewed a new Reservoir Mapping-While-Drilling technology being field tested for in-zone steering of horizontal wells and/or landing such wells at shallow angles of incidence relative to formation bedding (i.e., ≤ 13°). That technology, based on Deep Directional Resistivity (DDR) technology, was recognized as a potential solution by the Wheatstone Project team - assuming it would work in an application for which it was neither designed nor intended (i.e., angles of incidence as high as 30-45°). Ultimately, the technology was successfully tested at Wheatstone, and is now the Project's default method for landing all big-bore gas wells to the exacting level of accuracy described above.

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