Natural Gas Industry B (Aug 2020)
Stimulation experiment of horizontal wells filled with permeable and water-blocking gravel in deepsea bottom-water gas reservoirs
Abstract
In order to find an economic and effective water control method for horizontal wells in deep sea bottom-water gas reservoirs, we prepared modified coated gravel. Based on this, wear resistance, temperature resistance and water plugging capacity (WPC) tests were carried out on the coated gravel. Then, experiments were carried out using the 3D simulation device for the development of large-scale bottom-water gas reservoirs to compare the development effects of horizontal wells packed with conventional gravel and coated gravel in deepsea bottom-water gas reservoirs. And the following research results were obtained. First, the upper limit of temperature resistance of the gravel coating is 240 °C and the gravel packing speed can reach 4.48 m/s, which is 8 times the average flow velocity of gravel packing in actual open hole sections. Second, as the permeability of the coated gravel packing layer increases, its WPC gets weak. When the permeability is lower than 1500 mD and the displacement pressure difference is lower than 0.6 MPa, the WPC of the coated gravel packing layer is between 0.17 and 0.68. Third, the coated gravel layer functions as gas permeability and water plugging, so the horizontal well technology with coated gravel packing can reduce the flow capacity of water phase breaking into the dominant flow passage, so as to delay the rise of water production of gas well and prolong the gas production time. In this way, the gas recovery factor of bottom-water gas reservoir can be increased effectively. In conclusion, this technology has the function of spontaneous selective water plugging, i.e., “water plugging in case of water and gas permeability in case of gas”, and its technical and economic advantages are remarkable, which can provide a new idea for the water-control development of deepsea bottom-water gas reservoirs.
