| Popis: |
Located in southern Oman, the Mukhaizna heavy oil field has been under steamflood since 2007, but a shallower reservoir was later discovered in a flank area with no steam injectors nearby to extend thermal support to the new zone. The big challenge with cold production in this zone was the steep decline rate, which reached up to 50% per year. Multiple Horizontal Producers (HPs) are at pump-off condition (POC) and are working on a timer mode because there is insufficient inflow to keep the pump running 24 hours a day. The objective of this project was to steamflood this shallow sandstone reservoir to enhance its performance and productivity. A trial "with two pilots" was carried out in which the middle well of three HPs was converted to a Horizontal Injector (HI) to monitor steam injectivity, the response in the outer two producers, and the improvement in their productivity indices. The selection criteria were based on sand property similarities, channel continuity deduced from the seismic and geological interpretation, cross-sections, reservoir pressure, and production data that showed interference. The spacing between the HI and HP wells was considerable at 250 m, but the injected steam quality (SQ) for the First Phase was hovering around 99%, which is considered excellent. There were two phases in the trial, each lasting 6 months. The HP to HI conversions were done in December 2020 in two locations at different flux rates "which had negligible effects". Water cut increased significantly in both locations without any clear heat signals. The breakthrough was confirmed by taking salinity samples from the outer HPs. Some interesting observations and learnings have been extracted from the trial, which opened the door for new ideas to be examined. |
