Abstract

The 9/13a-A53 sub-horizontal well was drilled from the Beryl Alpha platform in order to target bypassed oil reserves and produce low GOR oil. This paper outlines the work of the multi disciplinary team from the planning through to production. The primary producing unit in the Beryl Field is the Middle Jurassic Beryl Formation. In the Central Area of Beryl Alpha, re-injected gas has preferentially moved down structure in the higher permeability upper Beryl Formation sandstones, overriding a substantial volume of oil. Well 9/13a-A53 was designed to target this oil. Innovative data acquisition strategies were employed during the drilling of the well. The approach to the well target necessitated crossing a 150 ft fault and sub-seismic faults/fractures were anticipated within the wellbore. No pilot hole was planned, instead an intermediate look-ahead' well seismic profile (WSP) was run to determine the position of the fault prior to drilling. Real-time logging while drilling (LWD) was incorporated in the drilling assembly to pick stratigraphic markers and react to possible directional drilling changes. This detailed planning resulted in the well being drilled on prognosis. In the well completion, a cemented liner was landed to allow selective perforation, away from potentially gas-conductive fracture zones. A monobore completion was utilized to improve future gas isolation operations and to optimize deliverability. The well came on-line in late 1992 and is currently producing low GOR oil at commercial rates.

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