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ABSTRACT: 3-D Seismic - An "Insurance" Policy


While the cost of 3-D seismic data is much greater than 2-D seismic, 3-D seismic could be thought of as an insurance policy and the associated additional cost as the premiums. A case in point is the Deep Saint Prospect within the Cypress Island Field, located in St. Martin Parish, LA. The prospect was generated using subsurface geology and the available 2-D seismic data. Subsequently 3-D seismic data was acquired. The primary objectives of the play were the Lower Marg tex (+/- 13,000 ft), Bol mex I and Bol mex III (+/- 15,000 ft). All three of the objectives drilled out structurally but were non-commercial.

However, there was a Miogyp sand at approximately 11,900 ft that tested high rates of gas. The Miogyp pay is expected to yield in excess of 35 BCF and has created a commercial project. With 3-D seismic data on the prospect, the Miogyp was quickly mapped with the confidence that small faults were creating the traps. This could not have been done with just the 2-D seismic.

Completing in the shallower Miogyp zone moved the prospective acreage approximately 2500 ft north of the original lease block due to the fact the well was directionally drilled with a 4,500 ft lateral deviation. This required additional leasing to protect the new discovery. Time was obviously of the essence. Having previously acquired 3-D seismic data ensured that only the appropriate leases were taken and thus saved an investment in both capital and time resources.

In summary, having acquired 3-D seismic prior to drilling the initial test well enabled a quick reaction to the results of the drilling, as opposed to waiting at least 12 months to have a seismic program shot, processed, and interpreted. The development phase of the prospect began at once, resulting in immediate cash flow.

AAPG Search and Discovery Article #90941©1997 GCAGS 47th Annual Meeting, New Orleans, Louisiana