The Tuba carbonate reservoir in the Sabriyah field, North Kuwait was deposited above the Wara shale and overlaid by the Ahmadi shale. It is divided into three stratigraphic units: upper, middle, and lower. This formation was considered to have limited opportunity for production enhancement. However, improved reservoir characterization along with developed pinpoint fracture acidizing technologies have provided new opportunities to improve recovery and increase pay zone productivity.
Pinpoint fracture acidizing technology, using drillpipe with a bottomhole pinpoint tool assembly, has helped to effectively stimulate pay intervals individually using acid fracturing treatments. This resulted in achieving multiple stimulation treatments in a single trip, where each treatment stage was tailored for the specific interval being treated. Moreover, this pinpoint technique increased the number of treated stages per well compared to conventional multistage fracture acidizing, which led to greater efficiency and greater production.
This technology has been successfully used for multiple zones in complex reservoirs to improve production and reservoir recovery. It provided an effective method to help boost production and injection from tight zones in openhole horizontal completions and completions where zonal isolation could be compromised. This treatment process helped optimize hydrajetting and acid fracturing technologies along with treatment design for individually placed fractures by using the dynamic fluid movement to divert fluid flow into a specific treatment point in the formation. This service required a different approach to treatment design by controlling and evaluating two primary fluid injection paths, which necessitates two separate pumping systems. However, a proper well candidate is important to the success of any stimulation treatment.
This paper discusses methodology and treatments applied on a recent well in the Tuba carbonate reservoir in a horizontal openhole completion. The technical approach taken during the design of the treatments is presented in detail, as well as the operational challenges encountered during the multistage fracture acidizing treatments. This stimulation technique was implemented successfully to perform a seven-stage acid treatment in a single lateral. The overall success of this project proves that there is a technical alternative to the traditional fracture acidizing methodology for wells of this type.