Publications

WELL-01 is an offshore oil and gas well that was drilled horizontally in October 2021. This well has a combination of cased hole and open hole. The low-permeability (<1 md) carbonate reservoir across the open hole (OH) section presented a significant producing potential. However, its production declined after an acidizing treatment in 2022 due to depleted reservoir pressure and low fluid level. It was identified that another acidizing technique and the installation of deepening gas lift (DGL) was necessary to lowering injection point.

This study describes the steps taken to optimize the matrix stimulation treatment of a high-potential, low-permeability carbonate reservoir located in the open hole section and the installation of a DGL to induce oil and gas production from that section. Another operational challenge was presented by the small platform with limited crane capacity, which made the use of coiled tubing (CT) and the deployment of long bottomhole assemblies difficult. Furthermore, operating in the 6 1/8-inch.OH horizontal section added to the complexity of the CT intervention.

The circular notching technique using a 2-7/8 inch. high-pressure rotary jetting nozzle effectively established 360° perforation at the most promising zone in the OH section, resulting in the creation of a preferential path prior to the acid treatment. The result of circular notching was evaluated using a multi finger caliper, and it successfully created 6-inch. radial penetration and 5-ft. vertical thickness. The use of a hydraulic agitator effectively assisted the CT in covering 1,100 ft of the unknown 6-1/8 inch. OH section until the primary acid treatment was performed at the target depth. Successful execution of the matrix acidizing operation and installation of the DGL increased well productivity by three folds. Due to the limited platform space, a catenary system was used, which helped in reducing the operational footprint. In addition, due to the limited crane capacity, a deployment method was required during the make-up of the DGL tools to accommodate the longest bottomhole assembly (45-ft).

This circular notching technique using a 2-7/8 inch high-pressure rotary jetting nozzle is an innovative development technique over the original one that used motor and high-jetting pressure gun. This different technique can potentially improve efficiency and cost-effectiveness of circular notching operations in any tight carbonate OH situation to enhance oil recovery. The use of a catenary system helped deliver a seamless and safe operation in very challenging offshore conditions with limited platform space and increased operator confidence for future projects. Distributed temperature sensing is suggested to help analyze flow intake across the section to be stimulated before the main treatment to aid with improved fluid placement for an optimized post-treatment production.