Angola Ultradeepwater Completion Designs Deliver Prolific Production
Authors: Wilson Adam 
Published: February 2015

This article, written by Special Publications Editor Adam Wilson, contains highlights of paper SPE 166257, ’Angola Ultradeepwater Development: Pinnacle Completion Designs Deliver Prolific Production,’ by J.F. Pena, A.Q. Joseph, N. Oakey, B. McNerlin, SPE, and S.A. Ralph, BP, prepared for the 2013 SPE Annual Technical Conference and Exhibition, New Orleans, 30 September-2 October. The paper has not been peer reviewed.

BP’s largest subsea development, PSVM, is the first ultradeepwater development in Africa and is the most expansive subsea development in the industry to date because of its water depth and geographical spread. It sits in 2000-m-deep water northwest of Luanda, Angola. This paper discusses the keys to the successful delivery and well productivity of the first seven of 40 planned wells of the development.

Introduction

The PSVM development is an ultradeepwater project offshore Angola (Fig. 1). The development will access resources from four fields—Plutao, Saturno, Venus, and Marte—which will be tied back to a single central floating production, storage, and offloading (FPSO) vessel. All 40 of the planned development wells are subsea, in water depths ranging from 1800 to 2050 m. Of the 40 wells planned, 22 are producers and 18 are injectors. All four fields produce from and inject into poorly consolidated Miocene turbidite sandstone reservoirs; consequently, downhole sand control is required for all development wells.

Sandface-Completion Design

The principal design objectives of the sandface completions for the development wells were

Access all net sand across multiple units separated by long shale intervals in trajectories from 0 to 90° and openhole lengths from 100 to 600 m.

Keep the formation sand in situ for producer wells, and design openhole water-injection wells highly tolerant of fines backproduction to the wellbore.

Provide assurance of installing robust sand control, and limit solids production to target levels.

Minimize equivalent circulating density for a low-fracture-gradient environment.

Minimize formation damage and shale reactivity, thus providing maximum productivity and injectivity by achieving mechanical skin factors of less than +5 for producer wells and less than +7 for injector wells.

Provide facility to incorporate downhole flow control or shale isolation through high-integrity openhole zonal isolation.

Use equipment with a proven track record where possible, and verify equipment reliability and integrity for first-time correct operation and 20-year well life.

Minimize losses to the formation while running the upper completion, and enable the completion to be landed, tested, and packer set without slickline or coiled-tubing intervention.

Producer-Sandface-Completion Basis of Design. The completion type assessed to be capable of meeting the design objectives for production wells was an openhole gravel pack (OHGP). Taking into consideration the properties of the rocks exposed in the long openhole sections and the operating environment, a viscous-gel-type gravel pack with alternative path functionality was selected over a circulating alpha/beta-type gravel pack, to provide increased assurance of installation success.