Practical Application of Reducing Fluid and Increasing Proppant Volume in Tight Sandstone Gas Reservoirs at the Eastern Margin of the Ordos Basin.

The Southern Region of Jiaxian is located at the eastern margin of the Ordos Basin, where multiple sets of tight sandstone reservoirs from the Upper Paleozoic are vertically developed. The main production technique employed in this region is platform well grouping with vertical and directional wells using layer fracturing technology. The reservoir exhibits an overall deviation in terms of its properties, with an average porosity of 7.1% and an average permeability of 0.52 mD. To effectively exploit multiple layers in the vertical direction, a high-intensity fracturing technique is employed for reservoir modification. The average clay mineral content in the reservoir is 10.3%, primarily dominated by weakly water-sensitive illite and kaolinite minerals (94%). The interstratified illite-montmorillonite content is less than 1%. The reservoir exhibits a relatively low degree of water sensitivity and damage. The reservoir has a poor pore-throat structure, with throat radii ranging from 0.3 to 1.7 μm and a pore-throat ratio of 80 to 300. This indicates the presence of water blockage damage within the reservoir. In response to the characteristics of the reservoir and development, an optimization approach is proposed to reduce fluid usage and increase proppant concentration in hydraulic fracturing operations. By reducing the pre-flush fluid volume, increasing the average proppant-to-fluid ratio, enhancing the pumping rate, and adjusting the viscosity of the fracturing fluid at different stages, it is possible to achieve a 30% reduction in fracturing fluid usage per well. This approach offers advantages such as ample reservoir modification, enhanced reservoir protection, and reduced hydraulic fracturing costs. The author has selected 124 Wells in the Nan District of Jiaxian for hydraulic fracturing and gas testing. By taking into account the reservoir characteristics, fracturing parameters, and gas testing results, an analysis model of factors influencing fracturing effectiveness has been established. This model will help determine economically effective design parameters for hydraulic fracturing. Based on the information provided, it is recommended to use a proppant intensity of 5–7 m3/m, a fluid intensity of 40–50 m3/m, and a pre-flush fluid ratio of 24–30% for the effective development of the Nan District in Jiaxian and the surrounding gas fields. These parameters can serve as technical references for the benefit-oriented development of the area.