Vol 2, PW 25 (06 Jan 99) Exploration & Production

INTRODUCTION: In its initial mandate to GCA, ONGC wanted to know the answers to 10 specific questions.

The following is a broad summary of the answers given by GCA in its preliminary report to ONGC dated 21 March 1998. ONGC: Is the current rate of production (approx.

260,000 b/d) sustainable GCA: Modest declines will continue but in the short term, it may be possible to maintain or perhaps increase production by 40-60,000 b/d. ONGC: What is the likely ultimate oil recovery with the current development mode GCA: Possibly 35-40% recovery could be achieved with a "pragmatic approach to ongoing field development.

Current recovery forecast is 28%. ONGC: What is the potential for production enhancement GCA: Extensive! Through enhanced water flooding; back pressure reduction and improved artificial gas lift; an aggressive search for lower cost solutions to drilling and workovers.

ie, barge-mounted treatment/pumping units, move to rigless workovers. ONGC: Assess present water flood system GCA: Too much water going down certain wells; sufficient facility capacity already exists to increase water injection.

ONGC: Assess the well-spacing GCA: Spacing needs to be significantly reduced. The present well spacing is inadequate for reservoirs of the size and complexity found in the Bombay High.

ONGC: Long term measures to accelerate production GCA: Introduce a multi-disciplinary team comprising: development geologist; petrophycisist; reservoir engineer; production engineer; workover engineer; process engineer; and an accountant. ONGC: How best to produce oil below the gas cap GCA: Use high angle wells; continue selective completions; limit drawdowns to prevent cloning; avoid gas injection.

ONGC: What is the feasibility of producing the gas cap without affecting the economics of oil recovery GCA: Not a good idea without massive water additional water injection; economics of modest gas production at Bombay High do not appear attractive relative to oil loss. ONGC: Ongoing activity required to progress the findings GCA: Use existing dynamic models; reservoir description, recreate the static model; incorporate 3D seismic when available.

develop a geologically-driven petro-physical model.