Recent horizontal drilling methods coupled with multi-stage fracturing has allowed E&P companies to access massive amount of resources from low permeability shale reservoirs. The initial productivity of these wells has been impressive; however, the decline rate and intervention frequency is higher than anticipated. Many of these issues are initially attributed to premature artificial lift failure due to solids abrasion or plugging, as well as abnormal productivity declines.
Generally, these reservoirs have been stimulated with hundreds of tons of proppant. This proppant, when placed into the formation improves the permeability for oil and gas to enter the lined section of the well. However, the primary fracture at the formation sand face can have low closure stresses at specific areas. A secondary contributor to this problem is specific to open hole packer liner systems. The proppant in the area between the outer diameter of the liner and the inner diameter of the borehole and between the packers does not have any closure stresses on it. As the oil and gas flows through this low stress annular area it can carry proppant into the liner of the well. Seismic events can also contribute to sand movement from the above listed conditions. All of these conditions allow proppant to move from a radial high permeability matrix in the reservoir to a linear ultralow permeability matrix in the liner.Further, the velocities of the fluid and gas in the liners of these wells are not adequate to carry all of the inflowing proppant to the artificial lift pump, and in most cases these pumps cannot produce the proppant to surface. When this proppant accumulates in the liner creating a low linear permeability matrix, oil and gas cannot flow through it; this has become an impermeable solids bridge that stops or significantly reduces production from all intervals below this depth. This is where the JetVak™ system excels.
Quantum's patented JetVak™ system offers E&P companies a unique solution to not only remove these impermeable solids bridges but to simultaneously gather valuable inflow properties from the reservoir during the same operation. With its patent-pending design, the JetVak™ uses a venturi to create a localized drawdown in the well while being cycled into the well. Simultaneously, a downhole pressure & temperature recorder and surface multi-phase monitoring is employed in order to map the entire production profile of the well. The venturi vacuums the wellbore debris and artificially lifts it to surface. Due to the concentric nature of Quantum's Dual Coiled Tubing (DCT), circulation is guaranteed. Our well intervention system cleans not only the entire wellbore, but also the surrounding formation. This can break down the formation skin, resulting in a higher permeability area surrounding the production casing. Sand bridges, which fully restrict communication of the downhole side of the wellbore from the wellhead, are given special care to ensure that all of the sand is removed to prevent continual build-up. The source of the problem is located and also taken special care of, typically the nearest downhole port.
Conventional cleanout methods such as tubing bailing, swabbing and conventional coil circulation are not as effective, dynamic and efficient as the DCT JetVak™ system. Through our case histories it has been proven that wells cleaned with the under-balanced JetVak™ system produce at a higher daily rate, decline at a lower percentage and run intervention free for an extended period of time.