Exploitation of Bypass Oil & Control of Undesirable Water Production; a Case Study of Mumbai High South

Uma Goyal, S. K. Anand, R. Saxena, and S. Chandrasekaran
MH-Asset, ONGCL, Mumbai, India

A re-development program has been undertaken in Mumbai High multilayered complex carbonate reservoir, to increase oil production from the field. After putting on production in 1976, the field had attained a plateau production level of about 4, 00,000 bopd during 1984-1990. The field experienced decline in oil production from 1990. Key issues for decline in production were increase in GOR, reduction in reservoir pressure and undesirable production of water. A number of steps were taken, viz., identifying bypassed oil, sidetracks as drain holes, enhancement of water injection and redevelopment of the field to arrest the decline.

Key issues in development of mature field have multiple objectives, especially maximizing production while minimizing capital expenditure and reducing the inevitable decline rate while minimizing operative expenditure. The collective approach to meet these objectives is the application of focused technology suitable for Mumbai High.

The present paper outlines the case histories of four wells, sidetracked using MRDH/LDST-LWD technology for tapping the bypassed oil on a platform. In all the wells the objective has been achieved by exploiting the bypassed oil & controlling the undesirable water and gas production. All the wells were sidetracked to different locations in ‘B’ layer of L-III reservoir and completed as drainholes for increased productivity. Sidetracking of these wells enhanced the oil production by 2240 bpd with reduction in water cut from 80% to 35%.

In Mumbai High South field sidetracking of wells with high angle build-up rates has received a fresh impetus for enhancement of oil production and control of undesirable water production from existing facilities.

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