Completed with 4.5 in tubing and 7 in Liner, the upper carbonate reservoir had previously been stimulated and produced until reaching its economic potential. To prolong the well life, the decision was made to permanently isolate the upper zone, then perforate, matrix stimulate and produce from the lower zone.The challenge for this operation was that the existing upper zone had been stimulated, creating a large void behind the casing with known high fluid loss. It was determined that isolation with cement would have only a small chance of success due to the high leak-off in the previously stimulated reservoir. Also, this zone was at a 40° inclination, making it more difficult to place an uncontaminated cement plug with Coiled Tubing (CT) and clean out the cement after placement.An inflatable packer was also considered to isolate the upper zone and perform acid stimulation on the bottom zone. The bottom-hole pressure and temperature (5,000 psi and 300°F) were beyond the operational limits of any inflatable element available in the region.For this unique situation, a new method was designed and successfully implemented. The new approach included first filling the upper zone with calcium carbonate chips (CaCO 3 ) to reduce or limit the fluid losses. Then, utilize CT to place a chemical isolation treatment. The product utilized was an organically cross-linked polymer (OCP) system capable of permanently sealing the target zone by forming a 3D rigid gel. It is effective for preventing water and gas flow in sandstone and carbonate formations from 100°F to 350°F (38°C to 177°C). A benefit of the treatment was the ease at which it could be pumped and placed via CT and then cleaned out. All that is required for cleaning is a nozzle and jetting action. The implementation of this chemical sealant procedure provided reliable zonal isolation of highly depleted upper zone and allowed full access (with CT, Slick Line and E-line) to deeper productive lower zone. The successful chemical isolation in this well has resulted in avoidance of expensive workover operations.This paper discusses the pre-job planning, benefits, challenges, design, execution, evaluation and lessons learned for applying this novel isolation method.

Hydraulic fracturing is recognized as a successful stimulation technique used to enhance recovery from reservoirs. Prediction of fracture initiation and propagation from wellbores is necessary for efficient hydraulic fracturing stimulation tasks. Perforating is key to the success of a hydraulic fracturing treatment; it provides a means of communication between the wellbore and reservoir. Additionally, in a fracturestimulated reservoir, the perforations serve as fluid conduits between the fracture and wellbore.Once the fracture is created, perforations provide the entrance to the fracture for the proppant. The perforation diameter must be sufficient to help prevent bridging because an accumulation of proppant can block the entrance hole. Inadequate perforations, low perforating efficiency, and variations in perforation entrance hole diameter can increase the effects of near wellbore (NWB) tortuosity and leave several holes that do not contribute to stimulation, causing uneven treatment distribution, increased formation breakdown pressure, and suboptimal completion-occasionally beyond the pressure capability of the surface equipment or design rating of the well.A new class of shaped charges engineered to maximize hole diameter while maintaining a consistent exit hole diameter independent of well profile and/or gun eccentricity has recently been introduced for unconventional resources requiring stimulation. Designed for perforating before a hydraulic stimulation, these new charges can help reduce the probability of screenout during the fracturing process.This paper describes the new charge technology in detail and addresses its successful deployment during fracturing of tight gas wells in Saudi Arabia. Specific examples are used to illustrate how the system facilitates prefracture evaluation, fracture initiation, and how fracture tortuosity and perforation friction entry values are decreased compared to previous perforating systems.

The objective of this paper is to highlight first worldwide implementation of coiled tubing (CT) compatible self-degradable fiber laden diverter for matrix stimulation treatment using enhanced high rate fiber optic real time telemetry system. The self-degradable fiber laden diverter has been used in bullheading acid stimulation treatments aimed to maximize reservoir contact and enhance gas production. Recently, the physical properties of fiber has been re-engineered enabling them to be pumped down coiled tubing to enhance diversion and stimulation effectiveness. Coiled tubing with fiber optic real-time telemetry has been utilized for many years in Saudi Arabia for matrix stimulation treatments and well interventions as it provides real-time bottom-hole parameters such as pressure, temperature, casing collar locator, gamma ray, tension and compression as well as distributed temperature sensing (DTS) to optimize fluid placement. The successes achieved with previously used 2 1/8-in. bottom-hole assembly (BHA) for coiled tubing with real time telemetry system offered the maximum rate of 2.0 barrel per minute (bpm), whereas this rate became a limitation to achieve the desired fiber concentration for diversion when fiber laden fluids were used. The low rate provision by 2 1/8-in. BHA led to the need of a new generation high rate 3.25-in. BHA to be used for coiled tubing fiber optic real-time telemetry system that can enable higher pumping rates, help in achieving the desired fiber concentration. For the first time in Saudi Arabian Carbonate reservoir, the novel fiber laden diverter was used during matrix stimulation treatment through 180 ft. perforated interval with new generation 3.25-in. bottom hole assembly (BHA) for coiled tubing fiber optic real-time telemetry system. The DTS used with the new generation coiled tubing high rate fiber optic real-time telemetry system helped in pre- and posttreatment evaluation. After successful high pressure coiled tubing stimulation using self-degradable fiber laden diverter with visco-elastic surfactant based acid system, the well performance exceeded expectation. The encouraging result was achieved by uniform stimulation coverage throughout the long perforation interval. The operation also proved the feasibility of using the new generation of fiber optic real-time telemetry system in challenging environment.

The objective of this paper is to highlight first worldwide implementation of coiled tubing (CT) compatible self-degradable fiber laden diverter for matrix stimulation treatment using enhanced high rate fiber optic real time telemetry system. The self-degradable fiber laden diverter has been used in bullheading acid stimulation treatments aimed to maximize reservoir contact and enhance gas production. Recently, the physical properties of fiber has been re-engineered enabling them to be pumped down coiled tubing to enhance diversion and stimulation effectiveness. Coiled tubing with fiber optic real-time telemetry has been utilized for many years in Saudi Arabia for matrix stimulation treatments and well interventions as it provides real-time bottom-hole parameters such as pressure, temperature, casing collar locator, gamma ray, tension and compression as well as distributed temperature sensing (DTS) to optimize fluids placement. The successes achieved with previously used 2 1/8-in. bottom hole assembly (BHA) for coiled tubing with real time telemetry system offered the maximum rate of 2.0 barrel per minute (bpm), whereas this rate became a limitation to achieve the desired fiber concentration for diversion when fiber laden fluids were used. The low rate provision by 2 1/8-in. BHA led to the need of a new generation high rate 3.25-in. BHA to be used for coiled tubing fiber optic real-time telemetry system that can enable higher fiber concentration at higher pumping rates. For the first time in Saudi Arabian Carbonate reservoir, the novel fiber laden diverter was used during matrix stimulation treatment through 180 ft. perforated interval with new generation 3.25-in. BHA for coiled tubing fiber optic real-time telemetry system. The DTS used with the new generation coiled tubing high rate fiber optic real-time telemetry system helped in preand post-treatment evaluation. After successful high pressure coiled tubing stimulation using self-degradable fiber laden diverter with visco-elastic surfactant based acid system, the well performance exceeded expectation. The encouraging result was achieved by uniform stimulation coverage throughout the long perforation intervals. The operation also proved the feasibility of using the new generation fiber optic real-time telemetry system in challenging environment.