Smart Multistage Technology Enhances Completion, Acid-Fracturing Stimulation

_ This article, written by JPT Technology Editor Chris Carpenter, contains highlights of paper SPE 229001, “An Innovative Smart Multistage Technology Adopted To Address Challenged Completion and Acid-Fracturing Stimulation Methods in High-Temperature-Formation Wells Through Advanced Dissolvable Technology, ” by Rommel Ernesto Arias, SPE, Mariam Al Saad, and Abdullah Thuwaini, Saudi Aramco, et al. The paper has not been peer-reviewed. _ In recent years, efforts have been made to improve multientry multistage fracturing (ME MSF) systems to increase reservoir contact within a single wellbore. However, longer lateral lengths are required to raise stage counts. An ME MSF technology was developed to address these limitations, enabling longer laterals and increasing stage counts while improving stimulation efficiencies and derisking operations. This technology incorporates intelligent, dissolvable darts that self-identify specific sleeves before activating to provide zonal isolation. ME MSF System The described ME MSF system was advanced to eliminate wireline deployment of fracturing plugs with perforation guns and eliminate coiled tubing operations. The system consists of intelligent dissolvable darts (IDD) that are programmed on surface and pumped to the target fracturing sleeve to be stimulated. These darts recognize the ME MSF sleeves without physical contact. This enables them to be pumped through the well at higher rates. The IDD opens the required sleeve before landing into a sleeve that provides the required isolation for the stage fracture. Once the fracture has been pumped, these darts dissolve to allow the well to flow without the need for coiled tubing intervention. The installation of these sleeves is performed when the casing or liner is deployed in the well. Each sleeve features an inner sleeve that is held in place with shear screws, and which is opened when an activated dart engages the sleeve. Pressure is allowed to increase, creating a differential pressure that provides the necessary force to shear the pins and open the inner sleeve, exposing a flow path from inside the liner to the reservoir; thus, zonal stimulation can proceed. Another key feature of the ME MSF system is that it is limited by neither the operational depth of wireline, nor the limitations of coiled tubing, nor the number of stages, as is the case with a graduated ball-seat system. Adapting Technology to High Pressure and High Temperature To ensure reliable performance in demanding tight-gas reservoirs, the ME MSF system was designed with specific enhancements. These included reducing the sleeve outer diameter from 5. 5 to 5. 25 in. , increasing the burst and collapse pressure ratings to 15, 000 psi, and maintaining the ability to rotate a 4. 5-in. liner into the wellbore during drilling if needed. The IDD also was engineered to meet demanding specifications and to dissolve in a controlled manner, allowing for well flowback without required coiled tubing intervention. IDD. These compact unactivated darts are programmed on surface to count the ME MSF sleeves (Fig. 1). Immediately after the programmed count has been recognized, the IDD activates to engage the next ME MSF sleeve. Updated operational requirements for the IDDs included an increase in differential pressure rating of 15, 000 psi and an increased temperature rating to 330°F, while maintaining the dart’s ability to dissolve within a time frame compatible with standard acid-fracturing flowback operations. Two proprietary materials were developed and selected for testing in high-pressure, high-temperature, high-brine-concentration environments. The tests validated that the IDD could withstand elevated pressures of 330°F for extended periods of time in fresh water and heavy brine.