Optimized Filter Cake Breaker Successfully Used in the OH Completions in Yuralpa and Oso Fields

Abstract

Oil provides 51% of Ecuador export earnings and a third of government revenue. Horizontal drilling has become an option to increase domestic oil production. The Yuralpa and Oso are land oil producer fields in Ecuador, which includes several wells. Some of the challenges include low pore pressure, sand control and the need of a filter cake breaker to enhance productivity. The reservoir drill-in fluid (RDF) and the breaker needed to be compatible, as well the operator required a breaker formulation that would not only allow the upper completion to be run before losing filtration control but also deliver superb productivity on completion after adequate soak time. It was also important that the solution as well required to be cost effective due to the low AFE that the operator had on the project. A water based breaker system, comprised of enzyme and chelant components, was chosen as the treatment selection. The thin RDF filtercake and the breaker treatment combination were tested in the laboratories to achieve an optimum technical and economical solution for the project. Due to environmental restrictions, sodium formate was used to provide density for drilling the horizontal hole section. After drilling, a mechanical and chemical wellbore clean up were performed, the pre-perforated liner was run, and the filter cake breaker was spotted at the open hole Potassium chloride brine was used as final completion fluid. Operations continue running in hole the upper completion assembly which some times includes an electric submersible pump (ESP). The usage of the novel breaker system allowed the project to achieve higher production rates than expected. Several wells have been successfully completed and put in production, all achieving or exceeding production expectations.