An Iteratively Coupled Model for Flow, Deformation, and Fracture Propagation in Fractured Unconventional Reservoirs

Author(s):  
Harun Rashid ◽  
Femi Olorode ◽  
Chukwudi Chukwudozie
Processes ◽  
2019 ◽  
Vol 7 (1) ◽  
pp. 28 ◽  
Author(s):  
Jianxiong Li ◽  
Shiming Dong ◽  
Wen Hua ◽  
Xiaolong Li ◽  
Xin Pan

Complex propagation patterns of hydraulic fractures often play important roles in naturally fractured formations due to complex mechanisms. Therefore, understanding propagation patterns and the geometry of fractures is essential for hydraulic fracturing design. In this work, a seepage–stress–damage coupled model based on the finite pore pressure cohesive zone (PPCZ) method was developed to investigate hydraulic fracture propagation behavior in a naturally fractured reservoir. Compared with the traditional finite element method, the coupled model with global insertion cohesive elements realizes arbitrary propagation of fluid-driven fractures. Numerical simulations of multiple-cluster hydraulic fracturing were carried out to investigate the sensitivities of a multitude of parameters. The results reveal that stress interference from multiple-clusters is responsible for serious suppression and diversion of the fracture network. A lower stress difference benefits the fracture network and helps open natural fractures. By comparing the mechanism of fluid injection, the maximal fracture network can be achieved with various injection rates and viscosities at different fracturing stages. Cluster parameters, including the number of clusters and their spacing, were optimal, satisfying the requirement of creating a large fracture network. These results offer new insights into the propagation pattern of fluid driven fractures and should act as a guide for multiple-cluster hydraulic fracturing, which can help increase the hydraulic fracture volume in naturally fractured reservoirs.


Author(s):  
Abhijith Suboyin ◽  
Md Motiur Rahman ◽  
Mohamed Haroun

Abstract Augmented by recent activities in the oil and gas industry, it can be seen that an economical and efficient hydraulic fracturing job has become critical for the successful development of unconventional reservoirs. However, exploitation of unconventional reservoirs is heavily water-intensive as compared to conventional reservoirs. Given this concern, it is essential to reform how water is managed within the industry, especially in water scarce regions such as the Middle East. In this study, a comprehensive investigation that deals with the quantification of changes with respect to variation in prime contributors within a traditional fracture design process is presented. This can assist to determine the distinct contributions of an element within fracture design parameters, as they are imperative to evaluate the nature of fracture propagation. After an extensive assessment, a set of natural fractures were introduced to the system and the system behavior was further investigated to identify their behavior and optimize resource management. Based on an iterative process, the results of the constructed simulation models were analyzed in depth and validated with field data. Overall, the results indicate that for the given field conditions, fluid and proppant optimization are critical to achieve maximum recovery. The dominance of parameters such as fracture width, fracture length, proppant placement and Young’s Modulus are also illustrated in depth. To examine the associated response on long-term productivity, the results have been extended to current field practices and cases. A rough analysis was conducted in-house, on geological data from a candidate field in the Middle East. Findings shows the potential to optimize and reduce the required water for an operation by 1.3 million gallons. This further highlights the need to optimize and tailor an adaptable workflow, which is proposed in this study, for water scarce regions such as the Middle East. In addition to ultimately assisting in verification of modern best practices, this investigative approach will create a paradigm for future studies within the Middle Eastern region to assist in a simplistic prediction of fracture propagation behavior and its associated response to optimize water usage. The results have also been extended along with comparisons to current field practices.


2016 ◽  
Vol 56 (1) ◽  
pp. 415 ◽  
Author(s):  
Yang Fei ◽  
Mary Gonzalez Perdomo ◽  
Viet Quoc Nguyen ◽  
Zhongyu Lei ◽  
Kunakorn Pokalai ◽  
...  

In many unconventional reservoirs, gas wells do not perform to their potential when water-based fracturing fluids are used for treatments. The sub-optimal fracture productivity can be attributed to many factors such as effective fracture length loss, low load fluid recovery, flowback time, and water availability. The development of unconventional reservoirs has, therefore, prompted the industry to reconsider waterless fracturing treatments as viable alternatives to water-based fracturing fluids. In this paper, a simulation approach was used by coupling a fracture propagation model with a multiphase flow model. The Toolachee Formation is a tight sand in the Cooper Basin, around 7,200 ft in depth, and has been targeted for gas production. In this study, a 3D hydraulic fracture propagation model was first developed to provide fracture dimensions and conductivity. Then, from an offset well injection fall off test, the model was tuned by using different calibration parameters such as fracture gradient and closure pressure to validate the model. Finally, fracture propagation model outputs were used as the inputs for multiphase flow reservoir simulation. A large number of cases were simulated based on different fraccing fluids and the concept of permeability jail to represent several water-induced damage effects. It was found that LPG was a successful treatment, especially in a reservoir where the authors suspected the presence of permeability jails. The authors also observed that total flowback recovery approached 76% within 60 days in the case of using gelled LPG. Modelling predictions also support the need for high-quality foam, and LPG can be expected to bring long-term productivity gains in normal tight gas relative permeability behaviour.


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