Using Pressure Transient Analysis to Optimize Field Development in Compartmentalized Shelf Margin Deltaic Reservoirs

W. H. Mills, K. L. Badgett, S. P. Mitchell, G. S. Vinson III

Analysis of pressure data taken in development wells played an important role in identifying compartmentalization in the two main pays at BP Exploration's MC 109 field. The shallower G Sand reservoir and deeper J Sand reservoir are interpreted as shelf margin deltas, however each has distinctly different compartmentalization issues.

The continuous character of the G Sand makes it easier to define the depositional system and investigate reservoir compartmentalization issues. A combination of well log, 3D seismic, pressure, and fluid information were the basis for the field model and yielded highly predictable well results. In the more distal J Sand however, it is possible to use the model only in a general sense. Complications with seismic amplitudes and a less reliable tie between wireline and seismic data require the use of additional techniques such as pressure transient analysis to efficiently exploit the reservoir.

BP's Gulf of Mexico group developed procedures to conduct effective well tests on conventional production wells and employed them during the development drilling phase of the project. Bottomhole pressure data were recorded during the initial few weeks of production. Typically, a 48 hour pressure buildup survey (surface shut-in) was obtained near the end of data acquisition. Analysis of the pressure transient information facilitated improvements in completion efficiency, and helped identify and quantify reservoir discontinuities. Integration of this information with the field model provided support for at least two wells in the drilling program thereby improving field development.

AAPG Search and Discovery Article #91020©1995 AAPG Annual Convention, Houston, Texas, May 5-8, 1995