Abstract
Although hydraulic fracturing is not a new technology, it has not yet been implemented in the United Arab Emirates. Abu Dhabi National Oil Company (ADNOC), the regional producer in United Arab Emirates, has set out to initiate the utilization of this treatment during year 2019. In this work, a systematic design procedure for hydraulic fracturing in tight petroleum-bearing reservoirs is proposed. The design caters for surface and subsurface flow parameters, and it is hoped to provide basic guidelines for ADNOC in this respect. The proposed design process incorporates both unified fracture design (UFD) methodology and the fracture geometry (PKN) model. Excel spreadsheets were developed and utilized to run sensitivity analysis for optimal performance and predict long-term production profiles before and after fracturing. The excel spreadsheets made are flexible in use, in the sense that they resolve issues with infinite/finite fractures, high/low surface injection rate as well as investigate for non-Darcy flow effects. Reliable published data were used to perform the necessary calculations. The results of the performance calculations have shown that it is possible to access commercial quantities of hydrocarbons from a tight reservoir. In addition, improved productivity by 15-folds and increased gas recovery of 1.02 MMMscf over the first 8 years of production can be achieved by proper hydraulic fracturing design and implementation in tight gas reservoirs. The results of calculations of non-Darcy effect revealed a threshold velocity of approximately 0.2 fps above which these effects could become significant in predicting the overall flow efficiency inside the fracture. To the authors’ knowledge, the literature has not fully addressed the hydraulic fracturing design analytically, and the methodology proposed in this work provides a complete design package which incorporates the UFD concept, the PKN model, the non-Darcy model, and long-term prediction of post-fracturing production performance, and applying the proposed approach in a case study.
Highlights
Tight carbonate reservoirs, less well understood and believed to require higher development costs and risks than conventional reservoirs, have become an important hydrocarbon resource
This value of Mp is cost effective in comparison with the higher values in Table 5
A maximum value of 15 for this ratio has been obtained for k = 0.01 md, which is indicative of the effectiveness of hydraulic fracturing treatment in tight reservoirs
Summary
Less well understood and believed to require higher development costs and risks than conventional reservoirs, have become an important hydrocarbon resource. Well stimulation is commonly applied to boost oil or gas production and, revenues therefrom. Hydraulic fracturing is a well-stimulation technique used commonly in low-permeability rocks like tight sandstone, shale, and some coal beds to increase oil and gas flow to a well from petroleum-bearing rock formations. Hydraulic fracturing has become a critical component in the successful development of unconventional reservoirs; including tight gas, oil and gas-producing shales, and coal bed methane, such resources rely on hydraulic fracturing for commercial viability (Al-Attar and Barkhad 2018). The execution of a hydraulic fracture involves the injection of fluids at a pressure sufficiently high to cause tensile failure of the rock. As additional fluids are injected, the opening is extended, and the fracture propagates to the design fracture half length
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