In an effort to improve well production performance targeting recent increases in oil demand, Saudi Aramco implemented several innovative technologies and practices in its offshore assets in the Arabian Gulf. The identified challenges which followed past practices were focused on enhancements to existing well completions, chemical treatments of damaged wells, implementation of Smart field technologies and early detection of casing leaks to enhance wellbore integrity and meet environmental standards.
This paper describes the methodologies of four technologies which were tested and implemented in three major offshore fields in Saudi Aramco. These technologies are the use of passive inflow screens combined with swellable packers in horizontal sidetracked wells to prevent premature water or gas encroachment, smart in-situ gas lift completion which utilizes the reservoir gas cap for artificial lift of oil wells, the chemical treatment of wells which endured formation damage and the utilization of a modified ultrasonic tool for early casing leak detection in aged wells equipped with up-hole packers.
All these technologies proved to be successful and their combined application added value to Saudi Aramco's operations. As a result, the production targets for 2006 were met and the positive results obtained from the implementation of these technologies will lead to the optimization and improvement of future operational practices.
Saudi Aramco operates three major offshore fields in the North part of the Arabian Gulf and horizontal drilling in these three fields is dated back to more than a decade. The company has been prudent in evaluating the technology of drilling and completing horizontal wells as it was progressed with time and constantly improving the designs of horizontal completions to maximize reservoir recovery. As the number of horizontal wells increased in the fields, the reservoir sweep efficiency is improved with time and higher production rates were accomplished on a per well basis when compared to vertical producers.
The geology in one of the fields is rather complicated with the existence of stringer sand bodies which are usually separated from the main sand by an impermeable shale break (Figure 1). The stringer sands were deposited uncontrollably in the subsurface and pose enormous challenge in the well placement and deciding on the direction of the wells when it comes to horizontal drilling.
The three major offshore fields were discovered in the mid-fifties and have been on production since then. Their petrophysical properties are characterized by clean coarse sands with very good permeability in the range of 3–5 Darcies (D). The recovery mechanism is by natural water drive and in some areas it is complemented by a gas cap drive. The sandstone reservoirs have pressure support by a strong water aquifer, which underlains the sand bodies.
