The hydraulic fracture propagation pattern induced by multi-stage temporary plugging and diverting fracturing in reservoirs with various lithologies: An experimental investigation

Abstract

Multi-stage temporary plugging and diverting fracturing (TPDF) is an effective method for generating hydraulic fracture (HF) networks. This study investigates various lithological reservoirs in the Xinjiang region, obtaining downhole full-diameter cores for experimental analysis using true triaxial TPDF. The characteristics of HF morphology are quantitatively assessed by employing computed tomography (CT) scanning. The findings are summarized as follows: (1) Initial hydraulic fracturing of specimens with different lithologies results in σH-direction double-wing HF, while the first TPDF generates a single-wing HF along the σh direction, and the second TPDF produces a single-wing HF along the σH direction. (2) The volume and area of HFs in the first TPDF of volcanic rock increased by over 30%. The first TPDF effect is more pronounced in conglomerate rock, with HF volume over 25% and surface area increasing by more than 35%. (3) During multi-stage TPDF, volcanic rock transitions from initial HF to the formation of new HF, sandstone diverts from the wellbore to create new HF, and conglomerate generates new HF through multi-point initiation in the wellbore and HF. Each TPDF process involves the propagation of existing HFs and the generation of new ones. (4) The breakdown pressure in multi-stage TPDF increased by 46.5% and 51.6% in volcanic rock, while in sandstone, the first TPDF increased by 90.6%. In conglomerate rock, multi-stage TPDF saw increases of 51.2% and 41.9%, respectively. These findings offer theoretical insights for optimizing TPDF design in diverse lithological reservoirs.