The South Tchibala 1HB-ST well discovered two potential Dentale-producing zones, the Dentale D1 sand and the Dentale D9. The first completion, in the shallower D1, included a hydraulic fracture treatment to increase the flow rate and recovery from the D1 interval.
However, production rates so far have been well below the minimum recommended operating range of the electric submersible pump (ESP), which has required more frequent well cycling to prevent damage to the pump.
The company has applied pressure transient analysis during well shut-in periods to determine the D1 reservoir characteristics in this area. Various analyzed pressure buildups indicate that multiple boundaries near the well and low permeability have combined to restrict the well’s capability to continuously flow oil at stable rates.
Production and shut-in cycling of the well will continue to determine if production improvements will occur and to support projections of future reserve recovery.
The additional Dentale D9 (15 m net hydrocarbons) interval can be tested and completed in the future, Vaalco added—its estimated OOIP range is 4 MMbbl to 15 MMbbl.
CEO George Maxwell said the company remained optimistic about the D9 formation and plans to recomplete that interval in the South Tchibala 1HB-ST wellbore in its next drilling campaign.
“We plan to drill additional wells in the 2021-2022 drilling campaign that could positively impact our production toward the end of the year and into 2023," he said. “The Etame asset is a premier, high-quality field that has produced over 126 MMbbl of oil since we began producing it over 20 years ago, and we believe there is still significant upside to be captured over the next decade.”