The oilfield Tchendo, located 18 miles off the coast of the Republic of Congo, has been operated since 1991 by Total E&P Congo in depths of approximately 100 meters of water.
The shallowest of the three reservoirs, the Sénonien reservoir (400 m TVD SS), involves an intercalation of carbonate layers with thicker (5 to 15 meters) but poorer quality siltstones.
Various attempts to enhance productivity on existing wells were unsuccessfully carried out since initial production, including selective or extensive perforation, acid treatments on the carbonate layers, and, in recent years, hydrajetting fracture stimulation on three wells.
Although the field is non-conventional, so far, it has been developed conventionally. A large amount of the original oil in place still remains in the reservoir. To make the redevelopment project viable, a step change in stimulation techniques is to be undertaken.
Two workovers were performed at the end of 2012 as a "proof-of-concept". Innovative fracturing technologies, including hydrajetting, were combined to deliver a non-sleeve scenario for horizontal well multi-stage fracturing. The workovers resulted in the largest fracturing treatment executed by Total on an offshore well.
This paper reports on the lessons learned in the process of fracturing this non-conventional reservoirs that will be capitalized for the future redevelopment of the project.