Well completion plays a critical role in the performance of a well in its entire life. More and more advanced well completion options are available for potential deployment in new wells, especially those in deep water and offshore; however, the cost could vary significantly from one completion type to the other. Considering the fact that completion takes a substantial stake in the whole CAPEX for a new well, the cost and the impact of the well completion is too significant to be ignored.
Two field case studies will be discussed in the present paper to demonstrate the possibility of cost saving through efficient completion designs. The first case study is focused on a deviated gas producer, and the second on a horizontal oil producer. The most popular completion options, including openhole gravel pack, cased-hole gravel pack, openhole, standalone screen, cased-hole frac pack, expandable sand screen, inflow control devices (ICD), intelligent well completions (DIACS), etc, will be considered in the completion selection. Other completion options such as alternating standalone screen and blank pipe that may slash completion cost without sacrifice of well performance will also be proposed and evaluated. Well performance will then be evaluated in details by assessing total well production, annular flow and flow inside the liner/tubing, pressure profiles along the annulus and along the liner, inflow from reservoir to annulus and fluid transfer between annulus and liner, and so on. Cost recovery, water and/or gas shut-off, formation damage, casing collapse, sand prevention issues associated with different completion options will be addressed.
A work flow aiming at optimizing well performance while maintaining completion cost at the minimum will be proposed.
Well completion plays a critical role in well design, and more importantly, the performance of the well in its entire life. With more and more advanced well completion options deployed in new wells, especially in the deep and ultra-deepwater environment, the cost and the impact of the well completion is too significant to be ignored.
The major motivation for the study is to illustrate the strategy and workflow that should aid to achieve an efficient completion design in regard to both cost saving and production efficiency. The procedure will be applied to two filed examples to demonstrate its application.
As anticipated, a wide range of well completion aspects, including completion performance review, completion design, completion selection, sand control, gas and water shut-off, best practices and lessons learned, etc., have been discussed in a significant number of SPE papers. A selection of the most recent studies is briefly introduced here for reference.
Powers et al reviewed the completion evolution in the Chirag field, compared the relative performance of completion types over a range of indicators, and discussed measures to take to improve open-hole gravel pack performance from a reservoir damage perspective. Ouyang & Huang compared the performance of horizontal and multilateral wells under different completion options. Total well production, annular flow and flow inside the liner/tubing, pressure profiles along the annulus and along the liner, inflow from reservoir to annulus and fluid transfer between annulus and liner have been evaluated.