The Midnight Sun field is located on the North Slope of Alaska near Prudhoe Bay (Figure 1). The field was discovered in 1997 by ARCO Alaska, Inc. and Exxon when drilling the Sambuca #1 exploration well. The discovery well encountered approximately 100’ of high quality Kuparuk sand analogous to the adjacent Pt. McIntyre field. The field was further delineated in 1998 with the Midnight Sun #1 well. Proximity to Prudhoe Bay infrastructure allowed early production from the Midnight Sun reservoir with production commencing in October 1998.
The Midnight Sun accumulation occurs in a low relief graben, containing an estimated 40 to 60 MMSTB of Original Oil In Place (OOIP). A gas oil contact (GOC) extends over a significant portion of the reservoir.
A 3D reservoir simulation model was constructed, calibrated to early field performance and used to study development options. A mid-field waterflood was identified as the best development plan. Simulation runs indicated that the mid-field waterflood would provide good recovery while isolating the upstructure gas cap for future depletion.
Waterflood operations commenced in October of 2000 using produced water from the Prudhoe Bay facility. Waterflood response was observed in the third quarter of 2001, characterized by increased oil production rate and a dramatic GOR collapse. Three additional wells were drilled in the fourth quarter of 2001 to complete the Phase II drilling program. Results from these wells have confirmed the geologic model used for development planning.