Experimental study on the mechanism of five point pattern refracturing for vertical &amp; horizontal wells in low permeability and tight oil reservoirs

Wang, Anlun; Yinghe, Chen; Wei, Jianguang; Li, Jiangtao; Zhou, Xiaofeng

doi:10.1016/j.energy.2023.127027

Cited by 10 publications

(6 citation statements)

References 32 publications

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“…However, due to the low permeability of a tight gas reservoir, economic production remains challenging. Using large-scale hydraulic fracturing technology to create a large stimulated reservoir volume (SRV), fracture networks can improve the productivity of the producers due to their higher conductivity. , Hydraulically VFWs not only enhance recovery rates but also reduce costs. , However, the area of SRV is finite; we also need to understand the geological condition of the unstimulated area. Consequently, it becomes essential to assess fracture and reservoir parameters for the efficient development of tight gas reservoirs with hydraulically VFWs.…”

Section: Introductionmentioning

confidence: 99%

“…2,3 Hydraulically VFWs not only enhance recovery rates but also reduce costs. 4,5 However, the area of SRV is finite; we also need to understand the geological condition of the unstimulated area. Consequently, it becomes essential to assess fracture and reservoir parameters for the efficient development of tight gas reservoirs with hydraulically VFWs.…”

Section: Introductionmentioning

confidence: 99%

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New Approach for Parameter Evaluation of Tight Gas Reservoirs Stimulated with Fracture Networks

Han,

Chen,

Liu

et al. 2024

Energy Fuels

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Tight gas reservoirs are divided into a stimulated zone and an unstimulated zone after hydraulic fracturing treatments. Due to the complexity of reservoir geology, many models have been established to evaluate the parameters of the fracture network and reservoir around vertically fractured wells (VFWs). However, owing to the impact of stress sensitivity, when tight gas reservoirs have strong heterogeneity, using well test curves to interpret the parameters of fracture and reservoir still has uncertainty. Bahrami et al. used a second semilog pressure derivative (SSPD) to reduce uncertainty in determining flow stages; however, SSPD has not been used to analyze VFWs in tight gas reservoirs with multizone and stress sensitivity. So, we calculated the dimensionless second semilog pressure derivative chart, which aided in identifying the flow characteristics during the middle and late stages. When pressure spreads to the transition flow stage, the pressure second derivative will show a "bulge" with the change of neighbor zone properties, and the number of "bulges" in the second pressure derivative is equal to the number of the outer zones. Meanwhile, it is worth noting that when the permeability modulus changes, the timing of bulge changes in the second derivative remains largely consistent, suggesting that stress sensitivity does not significantly affect the division of zones. The analytical model of VFWs was established in the Laplace domain, encompassing multiple zones and considering stress sensitivity. By utilizing Laplace and perturbation transforms, we obtained the bottom hole pressure (BHP) of the VFW through the implementation of the Stehfest algorithm. Then, a sensitivity analysis was conducted to study the impacts of zone radius, inner-to-outer zone mobility ratio, inner-to-outer zone storativity ratio, permeability modules, and fracture network volume ratio on the pressure transient analysis. This method can play a guiding role in devising zones in multizone composite gas reservoirs.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

New Approach for Parameter Evaluation of Tight Gas Reservoirs Stimulated with Fracture Networks

Han,

Chen,

Liu

et al. 2024

Energy Fuels

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“…Liao et al (2022) used the extended finite element method to create a model that coupled the first fracturing, water injection, and refracturing processes to optimize the refracturing orientation under heterogeneous pore pressure. Wang et al (2023) clarified the refracturing effect of a low-permeability reservoir under the condition of a five-point well pattern through laboratory experiments, revealed the refracturing mechanism of a straight horizontal well combination, and analyzed the dynamic characteristics of reservoir production under different soaking times. Although numerous studies have been conducted on refracturing and remarkable results have been achieved, the focus of the research analysis was the distribution of the reservoir stress field before refracturing however, a complete set of targeted refracturing timing optimization strategies has not been provided.…”

Section: Introductionmentioning

confidence: 99%

Refracturing time optimization considering the effect of induced stress by pressure depletion in the shale reservoir

Wang,

Yang,

Wang

et al. 2024

Preprint

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Refracturing is an important technology for tapping remaining oil and gas areas and enhancing recovery in old oilfields. However, a complete and detailed refracturing timing optimization scheme has not yet been proposed. In this paper, based on the finite volume method and the embedded discrete fracture model, a new coupled fluid-flow/geomechanics pore-elastic-fractured reservoir model is developed. The COMSOL commercial software was used to verify the accuracy of our model, and by studying the influence of matrix permeability, initial stress difference, cluster spacing and fracture half-length on the orientation of maximum horizontal stress, a timing optimization method for refracturing is proposed. The results of this paper show that the principle of optimizing the refracturing timing is to avoid the time window where the percentage of type-I (Type I indicates that stress inversion has occurred, \({0^ \circ } \leqslant \alpha \leqslant {20^ \circ }\); Type II indicates that the turning degree is strong, \({20^ \circ }<\alpha \leqslant {70^ \circ }\); and Type III indicates less stress reorientation, \({70^ \circ }<\alpha \leqslant {90^ \circ }\).) stress reorientation area is relatively large, so that the fractures can extend perpendicular to the horizontal wellbore. At the same time, the simulation results show that with the increase of production time, the percentage of type-I and type-II increases first and then decreases, while the percentage of type III decreases first and then increases. When the reservoir permeability, stress difference and cluster spacing are larger, the two types of refracturing measures can be implemented earlier. But With the increase of fracture half-length, the timing of refracturing method I is earlier, and the timing of refracturing method II is later. The research results of this paper are of great significance to the perfection of the refracturing theory and the optimization of refracturing design.

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“…In the context of the study on the five-spot method, Xiao et al [6] proposed that the five-spot well pattern exhibits significant potential for enhancing methane recovery in coal bed methane reservoirs. Wang et al [7] conducted a comprehensive study on the repeated fracturing mechanisms of vertical and horizontal wells within low-permeability tight oil reservoirs, specifically employing the five-spot well pattern. They elucidated the effects of repeated fracturing in low-permeability reservoirs within the framework of the five-spot well pattern.…”

Section: Introductionmentioning

confidence: 99%

Numerical Simulation Study of Pressure-Driven Water Injection and Optimization Development Schemes for Low-Permeability Reservoirs in the G Block of Daqing Oilfield

Wang,

Zhao,

Tian

et al. 2023

Processes

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Pressure-driven water injection technology shows significant potential in addressing the key challenges of low-permeability oil reservoirs, improving water flooding development efficiency. Grounded in FDEM theory, this study establishes fluid matrix constitutive equations and employs FDEM to resolve rock stress–strain fields. A numerical simulation method for pressure-driven water injection in low-permeability reservoirs is developed to study the impact of different well pattern densities. The results indicate that the 90° horizontal well pattern using the five-spot method yields optimal outcomes, with approximately 32.32% higher cumulative liquid production than vertical well patterns. The 45° horizontal well pattern with the reversed nine-spot method also performs well, with about 30% higher cumulative liquid production than single-row vertical wells. Pressure-driven water injection improves matrix oil–water permeability and expands water flooding coverage. Based on the pressure gradient distribution driven by different well patterns, an evaluation method for the inter-well utilization capacity and its effectiveness was established. This method quantitatively assesses the reservoir depletion under various horizontal well encryption schemes. For research on timing of water injection in pressure-driven water flooding. Compared to pressure-driven water injection after 90 days, there is increased cumulative oil production after 40 days, emphasizing the importance of early pressure maintenance for higher cumulative oil production and enhanced recovery rates in low-permeability reservoir development. These findings provide crucial theoretical and practical support.

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Experimental study on the mechanism of five point pattern refracturing for vertical & horizontal wells in low permeability and tight oil reservoirs

Cited by 10 publications

References 32 publications

New Approach for Parameter Evaluation of Tight Gas Reservoirs Stimulated with Fracture Networks

New Approach for Parameter Evaluation of Tight Gas Reservoirs Stimulated with Fracture Networks

Refracturing time optimization considering the effect of induced stress by pressure depletion in the shale reservoir

Numerical Simulation Study of Pressure-Driven Water Injection and Optimization Development Schemes for Low-Permeability Reservoirs in the G Block of Daqing Oilfield

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