Achieving Water Shut Off (WSO) with Targeted Epoxy Injections in Open Hole Gravel Pack Subsea Gas Wells

Methodology and results are presented for successful and unsuccessful zonal Water Shut Off (WSO) interventions for offshore subsea gas wells located in the Norwegian Sea with open hole gravel pack completions that do not have existing packers or other mechanical zonal isolation options outside of the screens. The field is produced by depletion and the water production needed to be halted to ensure the longevity of wells. The operations were performed from a Riserless Light Well Intervention (RLWI) vessel. First the water producing zones were identified. Water was then isolated by perforating at a 3.5 m section of blank pipe between two production screens and epoxy was injected into the gravel pack to create an annular flow restriction between the formation and sand screen by use of an epoxy injection tool. Shortly after the epoxy cured, a bridge plug was installed on the inside of the screens at the same depth. The WSO depth had to coincide with a local reservoir pressure boundary such as a sealing shale. The same WSO method was performed on three wells. These wells have produced between 1 and 4 million m3/d of gas, one well had water production from the first day of production and the other wells developed water after months of production resulting in water rates between 120-1000m3/d. Each well had varying levels of gravel pack quality between 50-100% and varying length/tortuosity; these factors became crucial to the success of the operation. All three wells will be discussed where 2 out of 3 of the wells had successful WSO with formation water eliminated from production. The interventions have extended the lives of all the wells by reducing fluid column weight (due to declining pressure) and boosting gas production given the water handling limitations of the facility. Two of the wells had such high water production and crossflow when shut in that they were expected to die within weeks without any further action by these interventions (refer to Table 1). Continued water production also decreased the viability of other wells in the same flow line, due to the subsea layout and associated limitation on maximum water handling capacity due to water increase. The operation was performed on 3 wells and the learnings and planning was taken from one well onto the next, improving with each iteration. The gathering and use of all subsurface and well/intervention disciplines with all available data to decide on best shut-off locations was key to the success of these interventions.