Practice and Insights of High-intensity Hydraulic Fracturing in Tight Gas Sandstone Reservoirs Using a Geology-Engineering Integration Approach

Changqing tight gas reservoirs possess substantial resources but are characterized by low permeability, low pressure, and low abundance, commonly referred to as the “three lows.” As field development advances, remaining reserves have become increasingly fragmented and of lower quality. The focus has shifted from Class I + II enriched zones to Class II + III marginal areas, where reserve abundance continues to decline annually, geological complexity increases and reservoir properties degrade. Gas layer thickness has decreased by 0.85 m, and permeability has declined by 0.2 mD. Additionally, development efforts have expanded from primary productive layers to secondary and newly explored formations. To overcome challenges related to reservoir engineering sweet spot identification, quantification of single-well controlled spatial target volume, and effective reservoir stimulation, a comprehensive geology-engineering integration approach has been implemented. This strategy enables the three-dimensional characterization of reservoir connectivity and introduces the 3Q-3D sweet spot identification method. By analyzing key parameters such as sand body distribution and in-situ stress, near-wellbore sweet spots are extrapolated into a three-dimensional framework. To maximize fracture-controlled stimulated reservoir volume, an advanced volume fracturing strategy has been applied. This includes intensive fracture clustering, high-intensity proppant pumping, controlled fluid volume with increased proppant concentration, and intra-stage temporary plugging. Experimental trials with proppant pumping intensities up to 3.0 t/m have resulted in a stimulated volume increase of over 20% and a production enhancement of 15%. These technological advancements have established a high-intensity volume fracturing model that integrates geological and engineering principles for tight sandstone reservoirs. This approach has significantly contributed to the efficient development of tight gas in Changqing, positioning it as the largest tight gas production base in China.