The Walnut Bend Field was discovered in 1938 and consists of over 70 Pennsylvanian channel sands draped over an elongated, anticlineal structure approximately 3 miles long and 1.5 miles wide.The main body of the field had produced over 99 MMBO by 1999 when a field revitilization project was initiated.This project was a success, both technically and commercially. The success of this program was due in large part on a new volumetric-balancing technology that provided accurate present day oil in place maps.Some of the highlights of this project are:
80% accurate prediciaon rate of current day hydrocarbons
1,080,000 bbls of reserves added
35% increase in production
Comprehensive multi-year revitalization plan.
Magnum Hunter Resources (MHR) acquired the Walnut Bend field in Cooke County, Texas in 1999.First discovered in 1938, there have been over 600 wells drilled in Walnut Bend. Production is from more than 60 Pennsylvanian reservoirs, mostly channel sands, which are draped over an elongated, anticlinal structure approximately 3 miles long and 1.5 miles wide.
Magnum Hunter was able to increase production and maintain this increase during the first year through more efficient field operations.By the year 2001 the field had returned to its historical decline rate of 10% (Figure 1).At this point, Magnum Hunter turned its attention to a detailed field study to evaluate all producing and possible reservoirs for recompletion candidates, new drilling locations, and potential waterfloods. A review of the available field data, the economic and time constraints, and practical considerations determined traditional reservoir simulation to be an impractical option. MHR decided to utilize a new Time Dynamic Volumetric Balancing (TDVB) technology to model the present day amount and location of hydrocarbons.In late 2002, this study was ready for implementation.
This technology proved to be a successful and valuable tool for planning the field workover.
TDVB provides present day maps of in-place recoverable oil. These were used to locate new wells and identify recompletion candidates. Field production has increased to over 750 BOPD from about 600 BOPD and over 1 MMBO of reserves have been added.
MHR acquired the Walnut Bend field in Cooke County, Texas, in 1999. By 2002, cumulative production was about 99 MMBO and production from the 90 active producers had fallen to 600 BOPD. Wells were completed in different reservoirs at various times throughout the production history of the field. Frequently, multiple reservoirs were commingled. And adding even more to the complexity, some of the reservoir intervals had multiple phases of waterflooding.MHR thought significant recoverable hydrocarbons remained, but the conspicuous absence of pressure data and the field production in 1999 did not justify the time and expense of conventional reservoir simulation, even if there had been enough input data.
It was decided that there was sufficient remaining economic potential to justify developing reliable geologic maps for each interval and utilizing a new volumetric balancing system (VBS) to bring the reservoir to current hydrocarbons in place status.