Expandable sand screen (ESS) is a sand control technique that has the potential to give a lower skin and therefore better productivity than other conventional sand control techniques, such as internal gravel packs (IGP's), openhole gravel packs (OHGP's), and stand-alone screens. However, welldocumented field cases in public literature that confirm this potential have not been reported to date.
Over the last few years, Brunei Shell Petroleum (BSP) has applied the ESS technology in both cased hole and openhole completions. The productivity data of the ESS-completed zones have been used in a comparison with data from similar zones completed with more conventional gravel packs.
In openhole applications in BSP's S.W. Ampa and Champion fields, production results show that the Productivity Index (PI) of ESS-completed reservoirs is equal to or better than expected, with one ESS zone having some 50% higher PI than similar OHGP zones. In cased hole applications in the Champion West field, the productivity of reservoirs completed with ESS is similar to or better than the productivity of similar reservoirs completed with IGP's. In all cased and openhole ESS-completions, no indications of sand production, screen plugging or screen erosion have been observed to date.
Expandable sand screen is an emerging sand control technology that can be applied in cased and openhole completions, as an alternative to internal gravel packs, openhole gravel packs or stand-alone sand screens. It offers several advantages over conventional gravel packs: easier logistics, simpler operations (with potential for rigtime savings especially in cased hole completions), larger bore access to the completed zone, better support of the formation in openhole completions, and potential for remedial zonal isolation. It also has the potential to give a lower skin and therefore better productivity than other conventional sand control techniques. The concept and the development of the ESS technology has been described in more detail in Refs 1, 2.
Since the end of 1999, BSP has been applying the ESS technology in both cased hole (5 wells) and openhole (4 wells) completions3, 4. In several campaigns similar wells and zones have been completed with ESS or conventional sand control methods, providing excellent comparison material between the two. The production data from these zones have been analysed and used in a discussion on the merits of ESS from the perspective of well productivity.
The S.W. Ampa field in the Offshore West concession area of BSP consists of many thinly stacked sand layers separated by shale stringers. Many reservoirs have a history of sand production thus making sand control a necessity. Sand control in openhole completions transecting multiple sand layers is particularly challenging due to shale instability issues. This field had a history of unsuccessful openhole gravel packs thought to be associated with the collapse of shale once the openhole was displaced to brine. Caliper logs showed that with increasing openhole time, the shale section became overgauge while tight spots developed in the sand sections.