Interaction Law between Natural Fractures-Vugs and Acid-Etched Fracture during Steering Acid Fracturing in Carbonate Reservoirs

Dai, Yifan; Hou, Bing; Zhou, Changlin; Zhang, Kunpeng; Liu, Fei

doi:10.1155/2021/6649874

Cited by 2 publications

(1 citation statement)

References 18 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…When Δθ = 90 °and Δσ ≥ 2 MPa or Δθ = 60 °and Δσ ≥ 4 MPa, HF initiation and propagation direction is normal to the NFs. Dai et al [12] studied HF propagation during acid fracturing in a true triaxial acid fracturing device. The results show that low-viscosity diverting acid promotes formation of the fracture network, and the fracture complexity is affected by NFs and pre-pad viscosity.…”

Section: Introductionmentioning

confidence: 99%

Numerical Simulation on Hydrofracture Propagation in Fractured-Vuggy Unconventional Reservoirs

et al. 2022

View full text Add to dashboard Cite

The unconventional reservoirs such as carbonate formation develops complex and diverse storage space structures, and it is composed of large-scale cavity, dissolved vug, and fractures. The carbonate reservoir is highly heterogeneous. Acid fracturing of carbonate reservoir is completed through the complex mechanical mechanism of interaction between vug and hydraulic fracture (HF). We use the equivalent method of reducing the rock strength by acid etching and serious fluid leakoff during interaction of HF and vug to establish a finite element (FE) model of HF propagation during acid fracturing in the fractured-vuggy carbonate reservoir. The model considers the effect of serious fluid leakoff during interaction between HF and vug, mechanism of interaction between HFs and the fracture-vug system, and change in acid etching intensity. Then, we carry out numerical simulation on impacts of injection rate, fluid viscosity, leakoff behavior in fractures and vugs, and natural fracture (NF) approaching angle on HF propagation in acid fracturing and compare the characteristics of injection pressure, fracture pressure, and HF size. It is suggested that the acid fracturing treatment should be operated by increasing the acid solution viscosity to reduce fluid leakoff, injecting fracturing fluid and acid fluid alternatively, increasing injection rate, and injecting fibers and ceramics when small pressure drop occurs during the HF interacts with the fracture-vug. When a large pressure drop occurs, it is suggested that the middle-low viscosity acid be injected at a low rate to etch the carbonate rock and enhance the fracture conductivity. HF propagates under higher pressure when the NF approaching angle is smaller.

show abstract

Section: Introductionmentioning

confidence: 99%

Numerical Simulation on Hydrofracture Propagation in Fractured-Vuggy Unconventional Reservoirs

et al. 2022

View full text Add to dashboard Cite

show abstract

Numerical Investigation of Liquid Flow Behaviors through Closed Rough Fractures in the Self-Propped Shale Formation

Wang

Chen

2022

Energies

View full text Add to dashboard Cite

The surface morphology of fractures formed by hydraulic fracturing is usually rough. The roughness of the fracture surface is the main reason the actual fracture conductivity deviates from the ideal flat plate model result. In this paper, based on the three-dimensional reconfiguration of actual rough hydraulic fractures, a randomly generated geometric model of a micro-convex body with a rough fracture surface is used as an example of a hydraulic fracture in a shale reservoir. Assuming that the flow in the fracture conforms to the laminar flow pattern, the velocity and pressure fields of the fluid flow on the fracture surface are solved by the finite element method. The effects of micro-convex body size, uniformity, density, and shape on the non-uniform flow of the rough fracture surface are analyzed. The three-dimensional model shows that the average velocity is minimum in the near fully closed fracture. The fluid bypasses the micro-convex body during the flow, forming multiple nonlinear flow regions. The streamlined tortuosity increases with the density and size of the micro-convex bodies and depends on the distribution of the micro-convex areas. The bypassing accelerates the pressure drop and slows down the flow rate. The greater the degree of micro-convex body aggregation, the more significant the decrease in flow velocity. The more locations where the curvature of the micro-convex edge is not zero, the more nonlinear flow zones can significantly reduce the flow rate and thus affect oil and gas production. Targeted optimization of the proppant placement pattern to make the trailing part of the micro-convex body as close to streamlined as possible can reduce the nonlinear flow area and slow down the flow rate reduction.

show abstract

Interaction Law between Natural Fractures-Vugs and Acid-Etched Fracture during Steering Acid Fracturing in Carbonate Reservoirs

Cited by 2 publications

References 18 publications

Numerical Simulation on Hydrofracture Propagation in Fractured-Vuggy Unconventional Reservoirs

Numerical Simulation on Hydrofracture Propagation in Fractured-Vuggy Unconventional Reservoirs

Numerical Investigation of Liquid Flow Behaviors through Closed Rough Fractures in the Self-Propped Shale Formation

Contact Info

Product

Resources

About