--> Abstract: Horizontal Drilling in Baldonnel Gas Reservoirs- A Case History of the Jedney-North Bubbles Gas Pools, by R. Hill, K. Peter, and T. Gordon; #90952 (1996).

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Abstract: Horizontal Drilling in Baldonnel Gas Reservoirs- A Case History of the Jedney-North Bubbles Gas Pools

Ronald Hill, Kubica Peter, Tebbutt Gordon

The Jedney-North Bubbles gas pools are trapped in anticlinal folds of the host Triassic dolostones against a northern subcrop edge. The pools have been on production since the early 1960s, with producing wells averaging 45 dam3/d and current reserve lives in excess of 10 years. Gross pay thickness of the reservoir is 46m, with the better matrix wells averaging 22m of 9.5% porosity. The reservoir is 'streaky' with lenses of primarily moldic porosity, through dissolution of the shell and crinoid components.

Petro-Canada drilled seven horizontal wells into the pools in 1993-1994. Flooding surfaces of 'high gamma' phosphate-rich laminae are correlatable, and allow subdivision of the Baldonnel into five distinctly different units. The middle or 'C' unit porosity was successfully targeted by all seven wells. Well length in the 'C' unit averages 800m, approximately 50% of that being porous.

All horizontal wells were evaluated with resistivity and nuclear porosity logs. Porosities calculated from the density log compared favourably with the core porosity. However, in porous intervals the neutron log indicated a large gas effect.

In some of the wells, resistivity image logs were run to obtain detailed information on structure; particularly fracture density and orientation. In addition, FMI images also provide valuable information on stratigraphy and reservoir continuity. In one of the wells an ARI resistivity log was run. The drilling program has been economically successful and provided a clearer, albeit more complex, picture of the reservoir.

AAPG Search and Discovery Article #90952©1996 AAPG Rocky Mountain Section Meeting, Billings, Montana