Permian Basin: Seminole San Andres Unit Residual Oil Zone CO2 Flood
The life of Seminole San Andres Field, which was
discovered in 1936, is being extended by development of the Residual Oil Zone
(ROZ) by Hess Corporation.
The San Andres formation,
the most significant pay zone in the field, was unitized for secondary recovery
waterflood operations in 1969. By the late 1980's the 17,000+ acre SSAU
contained some 600 wells and was well into its tertiary oil recovery phase with
a successful Main Pay Zone CO2 flood. Establishing CO2 flooding as a viable
recovery process at SSAU led to renewed interest in the Residual Oil Zone of
the San Andres formation. The ROZ contains similar STOOIP as in the San
Andres MPZ, but ROZ oil is only recoverable via a tertiary process such as CO2
flooding.
Two small scale projects
were implemented to evaluate ROZ response to CO2 flooding at SSAU. The Phase 1
project was developed with four 80 acre 2:1 line drive patterns with all
producers commingled between MPZ and ROZ. Phase 1 began CO2 injection in
July, 1996. The Phase 2 project was developed with nine 40 acre inverted
5-spot patterns with all producers commingled between MPZ and ROZ and all
injectors deepened to ROZ only. Phase 2 began CO2 injection in June,
2004.
Following the two pilot
projects, the SSAU partners agreed in 2007 to the first stage of the ROZ full
field expansion which included deepening producers and injectors in 29 patterns
and an increase of 70 MMSCFD gas handling capacity at the Seminole Gas
Processing Plant.
The Stage 1 project was
developed with 80 acre inverted 5-spot patterns with all producers commingled
between MPZ and ROZ and all injectors deepened to ROZ only continuous CO2 injection,
The MPZ flood changes in the project area from an 80 acre inverted 9-spot to an
80 acre 2:1 line drive. The project commenced in 2007 and was completed in
2009.
This presentation will
briefly review the performance of the two ROZ pilots and then discuss the Stage
1 project and show some early production performance from the Stage 1 area.
Location:
Westlake Club
570 Westlake Park Blvd.
Houston
,
TX 77079