Integrated Methodology for Optimizing Development of Unconventional Gas Resources

Gupta, Jugal; Zielonka, Matias G.; Albert, Richard A.; El-Rabaa, Abdelwadood M.; Burnham, Heather Anne; Choi, Nancy Hyangsil

doi:10.2118/152224-ms

Cited by 72 publications

(13 citation statements)

References 20 publications

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“…Poro-elastic stress reorientation and its impact on the trajectory of hydraulic fractures has been studied with field data (Warpinski and Branagan 1989;Weng and Siebrits 2007;Fischer et al 2009;Dahm et al 2010;Ajani and Kelkar 2012), lab experiments (Bruno and Nakagawa 1991), analytical estimations (Berchenko and Detournay 1997) and numerical simulations (Weng and Siebrits 2007;Singh et al 2008;Roussel 2011;Gupta et al 2012;Roussel et al 2013).…”

Section: Infill Well Hydraulic Fracturingmentioning

confidence: 99%

Strategies for Effective Stimulation of Multiple Perforation Clusters in Horizontal Wells

Manchanda

Bryant

Bhardwaj

et al. 2016

Day 1 Tue, February 09, 2016

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Increasing the efficiency of completions in horizontal wells is an important concern in the oil and gas industry. To decrease the number of fracturing stages per well it is common practice to use multiple clusters per stage. This is done with the hope that most of the clusters in the stage will be effectively stimulated. Diagnostic evidence, however, suggests that in many cases only 1 or 2 clusters out of 4 or 5 clusters in a stage are effectively stimulated.In this paper strategies to maximize the number of effectively stimulated perforation clusters are discussed. A fully 3-D poroelastic model that simulates the propagation of non-planar fractures in heterogeneous media is developed and used to model the propagation of multiple competing, fractures. A parametric study is first conducted to show how important fracture design variables such as limited entry perforations and cluster spacing; and formation parameters such as permeability, lateral and verical heterogeneity affect the growth of competing fractures. The effect of stress shadowing due to both mechanical and poroelastic effects is accounted for.3-D numerical simulations have been performed to show the impact of some operational and reservoir parameters on simultaneous competitive fracture propagation. It was found that an increase in stage spacing decreases the stress interference between propagating fractures and increases the number of propagating fractures in a stage. It was also found that an increase in reservoir permeability can decrease the stress interference between propagating fractures because of poro-elastic stress changes. A modest (about 25%) variability in reservoir mechanical properties along the wellbore is shown to be enough to alter the number of fractures created in a hydraulic fracturing stage and mask the effects of stress shadowing. Inter-stage fracture simulations show post-shutin fracture extension induced by stress interference from adjacent propagating fractures. The impact of poro-elasticity is highlighted for infill well fracture design and preferential fracture propagation towards depleted regions is clearly observed in multi-well pad fracture simulations.The results in this paper attempt to provide practitioners with a better understanding of multi-cluster fracturing dynamics. Based on these findings recommendations are made on how best to design fracture treatments that will not only lead to the successful placement of fluid and proppant in a single fracture, but in a set of fractures that are competing with each other for growth. The ability to successfully stimulate all perforation clusters is shown to be a function of key fracture design parameters.

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Section: Infill Well Hydraulic Fracturingmentioning

confidence: 99%

Strategies for Effective Stimulation of Multiple Perforation Clusters in Horizontal Wells

Manchanda

Bryant

Bhardwaj

et al. 2016

Day 1 Tue, February 09, 2016

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“…The fourth step involves taking this 3D distribution of reservoir pressure at the end of the production history to understand the state of stress for refracturing via a finite element model. As shown by Gupta et al (2012) and Marongiu-Porcu et al (2015), the FEM calculates the change in magnitude and orientation of the stress field. A pre-refracturing injection test can provide an estimate of the closure stress and can be used as a calibration point.…”

Section: Spe-175920-msmentioning

confidence: 99%

Improving Hydrocarbon Recovery of Horizontal Shale Wells Through Refracturing

Malpani

Sinha

Charry

et al. 2015

Day 2 Wed, October 21, 2015

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The learning curve has evolved in the last few years for operators in shale plays. Early wells started with relatively large cluster spacing and small proppant volumes resulting in suboptimal initial completions. Over the years, perforation cluster spacing has declined. Consequently, the number of hydraulic fracturing stages has increased. The total proppant pumped per lateral foot has also increased. The majority of the existing wells were completed with geometrically spaced multiple perforation clusters per stage. Sometimes more than six clusters per stage have been employed. Studies have shown that one-third of these perforation clusters are not productive (Miller et al., 2011). Noncontributing perforation clusters could be due to not initiating hydraulic fractures, insufficient proppant placement, or loss of near-wellbore connection due to over-flushing or severe drawdown. Furthermore, during the development phase, the depletion from parent wells leads to asymmetric hydraulic fracture growth on closely spaced infill wells. Parent wells may also be negatively impacted due to hydraulic fracture interference from new completions. These factors have led to poor hydrocarbon recovery factors, sometimes less than 10% in horizontal shale wells.Recovery factors from existing wells can be improved through restimulation. Candidate selection is a key in achieving economically successful restimulation. Restimulation of appropriate horizontal shale wells resulted in significant production uplifts based on early field results. Designing a fit-for-purpose restimulation treatment is dependent on initial completion, offset well distance, infill plan, and, above all, economics. On top of the design aspect, operationally achieving effective restimulation on long horizontal wells with tens of perforation clusters is a challenging task. Thus real-time monitoring and control is a key for field execution.This work uses an integrated petrophysical, geomechanical, hydraulic fracture, and reservoir modeling workflow and field observations to develop restimulation strategies for improving hydrocarbon recovery. This integrated workflow includes a multistep calibration process to reduce uncertainty. One of the key calibration steps is to model hydraulic fracture growth accounting for local geological heterogeneity and match with observed treatment parameters and microseismic interpretations. Another critical calibration step includes automatic gridding of hydraulic fracture geometry to run numerical reservoir simulation to match realized production results. Reservoir pressure distribution at the end of the production history is used to recalculate stresses for modeling the refracturing scenarios.Multiple practical refracturing scenarios were constructed for addressing near-wellbore connectivity issues and ineffective drainage along the lateral. Creating new surface area in undrained rock and restoring productivity of existing hydraulic fractures resulted in higher recovery. Higher proppant amounts in undrained rock on one well pad or late...

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“…Another way to decrease pressure gradients responsible for stress reversal in the infill region would be by shutting-in the producing offset wells for some period of time before infilling (Gupta et al 2012). While we have already verified the high sensitivity of stress reorientation to the pressure drawdown, it is still unclear how long of a shut-in period would be required to reverse the direction of the principal horizontal stresses back to their in-situ state.…”

Section: Shut-in Of Offset Wellsmentioning

confidence: 99%

“…An important difference is in the scale of investigation, as the geomechanical interactions can be felt far from the wells across the whole field, as measured by Minner et al (2002). Recently, Gupta et al (2012) uncovered that reservoir depletion from existing wells can have detrimental impacts on fracture propagation in infill wells, and subsequently lower well productivity. In particular, in cases of low horizontal stress anisotropy, the intermediate stress direction was shown to reorient parallel to the infill well, potentially leading to longitudinal fractures.…”

Section: Introductionmentioning

confidence: 99%

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Hydraulic Fracture Propagation from Infill Horizontal Wells

Roussel

Florez

Rodríguez

2013

SPE Annual Technical Conference and Exhibition

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As pressure increases or decreases non-uniformly as a result of well injection/production, stresses vary anisotropically in the reservoir. The principal stresses, which govern the propagation direction of hydraulic fractures, are thus modified not only in magnitude but also in direction. Previous modeling efforts and field observations have demonstrated the impact of stress reorientation on the refracturing of vertical wells and the multi-stage fracturing of horizontal wells.Using a state-of-the-art coupled symmetric Galerkin boundary-element method (SGBEM) and finite-element method (FEM) model, we simulate the impact of prior production from offset wells on the propagation direction of fractures initiated from an infill horizontal well. Geomechanical calculations demonstrate the occurrence of stress reversal in the infill region following a period of production from the offset wells in the order of years. The numerically simulated hydraulic fracture network in the infill well is shown to contact a smaller reservoir area past the onset time of stress reversal, as the induced fractures gradually turn to orient parallel to the infill well. The risk is to see the performance of the infill well drop compared to the offset wells. On the other hand, a window of opportunity exists when the horizontal stress contrast is reduced compared to in-situ, thus favoring the interaction with natural fractures and enhancing fracture complexity.These new observations have significant implications for field development strategies, hydraulic fracturing design, well placement and spacing, as well as the timing of infill-well stimulation, especially in shale plays where poroelastic stress reorientation is sustained over the life of the reservoir. SPE 166503bigger role than fluid flow interference depends largely on the value of the in situ stress contrast. In cases featuring large in situ horizontal anisotropy, stress reversal is unlikely to occur and fluid flow interference is then likely to dominate.Studying of the impact of pressure-induced stress changes on fracture propagation direction is by no means of recent interest (Berchenko and Detournay 1997). In tight gas plays, poroelastic stress interference has been investigated and applied to the refracturing of vertical wells (Roussel 2011;Roussel and Sharma 2010a, 2010b;Siebrits and Elbel 1998;Warpinski and Branagan 1989;Weng and Siebrits 2007). In the case of a previously fractured well, it is possible to create a secondary fracture that is perpendicular to the first. Thus, refracturing makes it possible to access zones of the reservoirs that were previously unstimulated or understimulated. Initially, the direction of maximum horizontal stress is aligned with the initial vertical fracture. During production, the maximum horizontal stress decreases faster than the minimum horizontal stress, causing principal stresses to be reversed in the vicinity of the fracture. As a result, the second fracture may propagate orthogonal to the initial fracture. Past the isotropic point (L f '), the...

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Integrated Methodology for Optimizing Development of Unconventional Gas Resources

Cited by 72 publications

References 20 publications

Strategies for Effective Stimulation of Multiple Perforation Clusters in Horizontal Wells

Strategies for Effective Stimulation of Multiple Perforation Clusters in Horizontal Wells

Improving Hydrocarbon Recovery of Horizontal Shale Wells Through Refracturing

Hydraulic Fracture Propagation from Infill Horizontal Wells

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