Abstract
Water control in mature heavy-oil reservoirs is a well-known challenge in the Oil & Gas industry. Due to the mobility ratio, water tends to flow much easier compared to oil, leading to premature water breakthrough which pushes water cut values to over 95% or more within weeks of oil production. High volumes of water production negatively impact operations due to excessive electricity consumption (lifting and re-injection), overuse of water handling/treatment facilities and its associated impact to the environment. In some fields, high water-cut can limit the oil production if the water handling capacity is exceeded, driving operators to shut-in wells and lose recoverable oil.
Villano is a mature heavy-oil field located in a tropical rainforest area in the Pastaza province, east Ecuador (17–19 °API and 25 cP). The field has been mainly developed with horizontal wells, where several water-control completion strategies have been trialed (ICD/AICD) due to the presence of an infinite-acting, strong aquifer drive. Although some positive results had been observed in the field, none of these technologies have been able to provide effective water control in the sections with water breakthrough.
After a technical evaluation, the AICD-Valve technology was chosen, and the first installation was planned for mid-2021. Due to its ability to autonomously restrict water flow based on the fluid properties (viscosity and density), simulation results showed short- and long-term benefits in terms of oil recovery and water control for the field.
The AICD-Valve technology has shown superior water control compared to other technologies used in Villano field. The well began its production with 4% water cut (compared to >50% with adjacent A/ICD completions) and approximately double the initial oil rate compared to modelling. The well eventually reached 80% water cut and stabilized at 80%–85%. Production rates have been very stable while the flowing bottomhole pressure has been dropping gradually, signaling that the AICD-Valves are autonomously choking the water zones while allowing production from oil zones. Water volumes produced from the AICD-Valve well are less than 1/3 of the neighboring A/ICD wells.
