Experimental evaluation and optimization of improved conductivity of gelling acid etched fractures in deep, low-permeability reservoirs

Stimulation technology is the key to efficient development of deep low-permeability carbonate reservoirs. For such reservoirs, where the porosity and permeability are low, or where the reservoir is far from the borehole. An efficient production increase can only be achieved by using a deep percolation gelling acid fracture technique, maximizing the length of the acid etched fracture to expand the percolation area, and improving the conductivity of the acid etched fracture. A quantitative experimental study of the conductivity of acid etch fracture based on an acid rock tiling instrument, a 3D laser scanner, and an acid etch fracture conductivity evaluation device identified three typical supporting morphologies of gelling acid etch fracture walls: spot, line, and sheet. A systematic quantitative description and evaluation of the etch morphology of rocks etched by acid has been performed. The fracture morphology of acid etchings has been quantitatively evaluated under various experi-mental conditions such as fracture width, temperature, acid fluid consumption, displacement, and different acid fracture processes and their laws affecting fracture conductivity. The conductivity of acid corrosion fracture increases with the decrease of fracture width, and decreases with the increase of closure stress. The greater the amount of acid used, the higher the fracture conductivity; With the increase of flow Reynolds number, the conductivity of acid corrosion fracture shows a trend of increasing first and then decreasing. The fracture con-ductivity was compared and analyzed for different property placement conditions under the acid sand carrying technique, and the main effect of the acid etch fracture conductivity was identified. Optimization of high con-ductivity and deep penetration gelling acid fracturing techniques can help guide the design of acid fracturing and improve stimulation and recovery effects, thus achieving the goal of efficient development of deep, low permeability carbonate reservoirs to increase reserves and production.