Anchor Project: The Subsurface Journey from Discovery to Development
Authors: Ogden K. , Bordenave T. , Luo Y. 
Published: April 2024

The Anchor reservoir is approximately 140 miles off the coast of Louisiana in the deepwater Gulf of Mexico (GOM). The Wilcox reservoir is at depths of 30,000 - 34,000 feet true vertical depth (TVD) with initial bottom hole pressure from 23,000 - 27,000 psi. This paper will provide an Anchor field subsurface overview from discovery to development.

Appraisal drilling, comprehensive data acquisition and analysis supported maturation of the Anchor field in deepwater GOM. The execution and interpretation of a new Ocean Bottom Node (OBN) seismic survey enhanced reservoir characterization and influenced placement of Stage 1 wells. The development of the Anchor asset combines technical and operational experience from another Chevron-operated GOM asset in the Wilcox trend with application of 20,000 psi (20k psi) technology to bring the Anchor field to production. During the development drilling campaign and early production years, focused data acquisition will continue to be applied to improve understanding of field performance and give insight on potential future development.

Data from each appraisal penetration was used to build probabilistic static and dynamic reservoir models incorporating key reservoir uncertainties. A final investment decision (FID) development plan was established for seven wells to be produced under primary depletion with commingled production from up to four Wilcox zones. Recognizing that seismic quality was challenged in some regions of the field, an OBN seismic survey was conducted in 2020. The survey improved seismic quality compared to legacy volumes and led to adjustments to the East boundary fault and expansion of the high confidence development area. Additional advanced reprocessing was performed in 2023. Development drilling started in 2021 with AP001 drilled close to the discovery well with the Deepwater Conqueror. A second development well, AP002 was drilled to total depth in February 2023. Both development wells were suspended and will be completed using multizone frac pack completions with the new Transocean Deepwater Titan 20k psi rig.

Production from the Anchor field will benefit from implementation of several recent technologies already in use in deepwater assets which have been adapted and qualified for high pressure application. A Multiphase Pump (MPP) on the seafloor will enable greater drawdown of the reservoir and boost production to the floating production unit (FPU). Multiphase Flowmeters (MPFM) will be installed at the tree for each producer and combined with downhole pressure gauges will allow close monitoring of well and field performance. Chemical tracers which are activated by exposure to either oil or water will be pre-installed in downhole screens with unique tracers assigned to each completed interval in each well. When sampled, the presence of the tracers will indicate if all completed zones are actively contributing to blended production.

For clarity, the following terms are used throughout this paper. High Pressure High Temperature (HPHT) refers to equipment rated to pressures greater than 15,000 psi and/or temperatures equal to or greater than 350°F. Anchor is a high pressure project under the HPHT category. 20K refers to the Anchor project's technology development and qualification program.