More than 40 years of production has confirmed that the UG (MO) reservoir receives very little natural pressure support in some areas. The introduction of a new Production gathering center has increased the field production 6 folds. At current reservoir conditions and production strategy, the production will stay on plateau for only 3 years. This is mainly due to the rapidly falling reservoir pressure. The remedial plan is to initiate a full field water injection project to maintain reservoir pressure.

The primary objective of this project was to extend production plateau as long as economically possible. The reservoir pressure for the field, as well as different areas within it, is declining rapidly. The most important cause of this reservoir pressure decline is the high off-take rate (compared with the aquifer influx rate) and the lack of a reservoir pressure support such as water injection. This suggests that the water injection option is needed to support the reservoir pressure and extend the oil production plateau.

In this project, many development options were considered. These options can be grouped into three main groups: water injection, infill drilling and combined development options. In the water injection option, comparisons were considered. These options are surface injection vs. dumpflooding, pattern vs. peripheral injection, injection into the oil column vs. injection into the water zone. In the drilling option, comparison between infilling and sidetracking was done. Basically, within each option there was an optimization process, which consists of many sensitivity cases. The purpose behind these many cases is to optimize each option before being combined and get better results than when used alone. For example, in the water injection option, sensitivities were run to see the impact of number and location of injectors. Also, within that case, sensitivities were run to see impact of not achieving a target injection rate. For the infill drilling option, many cases were run to optimize the number of producers. For the combined development options, sensitivities were run to determine best-combined option and to study impact of water injectivity issues.

Technical Contributions:

  1. Will demonstrate the design of a fullfield water injection scheme to maintain reservoir pressure.

  2. Will demonstrate the applicability of dumpflood to repressurize a constantly depleting reservoir.

  3. Will demonstrate a cost-effective technique to maintain reservoir pressure.

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