Improved Well and Reservoir Management in Horizontal Wells Using Swelling Elastomers

Abstract

Abstract Petroleum Development Oman (PDO) is producing substantial amounts of unwanted water or gas from most of its oil fields. To increase recovery from maturing reservoirs, PDO is developing the capability to detect and shut-off unwanted water and gas. Swelling elastomers have been deployed to segment horizontal wells in combination with surveillance and shut-off technologies. In beam pump wells dual wellheads have enabled logging while pumping. A key element to achieve improved oil recovery through well and reservoir management in a horizontal well is segmenting the well into different flow units. Swelling Elastomers (SE) are being deployed to enable segmentation. SE tool provides zonal isolation through the swelling of the elastomers when contacting produced water in the wellbore. In clastic reservoirs the completion philosophy has been changed from drilling minimum functionality wells to wells with closed-annulus completions that allow for surveillance and interventions. Surveillance is done in the drilling phase with under-balanced drilling and other open hole logging measurements. In the work over phase unwanted flow segments have been detected by logging while pumping coupled with greater integration of available reservoir data. Mechanical segment shut-off methods have been used. To date PDO has segmented more than 100 horizontal wells with swelling elastomers. In more than 20 wells suspected water producing feature were isolated at the initial completion stage and the rest were segmented based on reservoir flow unit characterization. After having proved that SE is delivering value in initial water shut off, the strategy is to prove a viable surveillance technique to identify water entry point in horizontal wells, and to develop several reliable water shut off (WSO) techniques depending on which segment's to be closed and if reversibility is required. To date more than one million barrels of oil have been realized as a result of the initial isolations as well as subsequent water shut offs. This paper is a continuation to the work presented in SPE paper number 91665 and will present case histories of the delivery and management of wells with swelling elastomer in clastic reservoirs in Oman