Design and Qualification of a Remotely-Operated, Downhole Flow Control System for High-Rate Water Injection in Deepwater

Abstract

Consistent with the concerns of many deepwater developments being contemplated throughout the world, this paper reviews the challenges, methodologies and detailed conclusions associated with the implementation of selective water injection for pressure support in ultra-deepwater, subsea developments operated by BP. The potential benefits associated with remote control of selective water injection in any of 2 – 6 zones within a single well, include reducing well count, reducing interventions and increasing recovery. This paper focuses on the operational requirements and considerations associated with the development of soundly engineered intelligent well systems, capable of a 15-year design life, with sustained injection of 45,000 BWPD per well, into any remotely selected zone. Principal areas of discussion include: mitigation of potential erosion at these rates through 3–1/2" tubing flow control valves within 7" liner completions; inter-zonal isolation competency with differential pressures up to 7,500 psi; and downhole hydraulic systems design for remote-control at hydrostatic pressures of 18,000 psi and differential pressures up to 12,000 psi. In addition to the downhole extremes in flow rates and pressures, we discuss the considerations within the subsea control systems of these wells; the assessment of various downhole hydraulic control architectures; and the effects of the operating temperature extremes. The principles, processes and ‘lessons learned’ in design of this system can serve as a benchmark for other high-value, deepwater, subsea injection applications in which the reservoir barrier conditions are not well understood, and hence considered candidates for intelligent well systems. Introduction Many deepwater oil projects around the world are planning to rely on water injection for pressure support and maximization of oil recovery. As depths and pressures increase, the requirements placed on the downhole systems increase, in some projects beyond currently available equipment. The development and qualification of water injection well completions technology required to meet these technically challenging requirements is the central focus of this paper. Many if not most significant deepwater geologies are comprised of multiple stacked reservoirs. In many of the reservoirs there are multiple sand layers separated by significant shales. With reservoir sections hundreds of feet thick, and waterflood the main depletion mechanism, control of injection water placement becomes essential to prevent early water breakthrough and to achieve effective oil sweep and recovery. This task is complicated by variation in permeability and thickness among the pay sections. Downhole flow control (DHFC) enables controlled water placement. The ability to toggle between zones is also seen as a valuable optimization feature of downhole flow control. When water injection wells are completed with subsea trees, interventions are very expensive. A simple reduction in number of interventions to change injection intervals generates significant value. The elimination of downtime while planning interventions, waiting on rigs, etc. accelerates production, adding further value. Stranded reserves resulting from uneconomic workovers can also be eliminated by the use of downhole flow control. In recognition of the significant value potential, Baker Oil Tools and BP's Exploration and Production Technology Group have been working on the development of DHFC technology to meet the requirements of some deepwater projects for which currently available equipment is simply not sufficient.

Testing and Analysis of Wells Producing Commingled Layers in Priobskoye Field

“…These objectives are similar to the motivations for smart completions and Downhole Flow Control (DHFC) ideas (e.g., Bussear andBarrilleaux, 2004, andBarrilleaux andBoyd, 2008). As in many onshore fields, in the Priobskoye Field, cost is an important consideration which dictates the optimum solutions rather than the application of the best technologies.…”