Role of Stress Reorientation in the Success of Refracture Treatments in Tight Gas Sands

Roussel, Nicolas; Sharma, Mukul M.

doi:10.2118/134491-ms

Cited by 26 publications

(11 citation statements)

References 29 publications

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“…The features of the model that are used in this investigation are: 1) Fully coupled simulation through simultaneous numerical solution to the Lubrication Equation for laminar, Newtonian fluid flow in the fracture, elastic deformation of an isotropic, impermeable, homogeneous rock, and fracture propagation according to Linear Elastic Fracture Mechanics. Note that by limiting consideration to an impermeable rock, we eliminate the possibility of poroelastic stress changes such as those considered by Roussel et al (2010). 2) Determination of the crack path according to the maximum tensile stress criterion of Erdogan and Sih (1963).…”

Section: Numerical Simulationmentioning

confidence: 99%

Parameters Effecting the Interaction among Closely Spaced Hydraulic Fractures

2011

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Placing multiple hydraulic fractures at intervals along horizontal wells has proven to be a highly effective method for stimulation. However, the mechanical interaction between a growing hydraulic fracture and one or more previous hydraulic fractures can affect the fracture geometry such that the final fracture array is suboptimal for stimulation. If the fracture array geometry is idealized as a set of regular and planar fractures, history matching and production forecasting may be inaccurate. During the treatments, the fractures can curve towards or away from one another, potentially intersecting one another. A detailed parametric study of this phenomenon using a coupled 2D numerical fracturing simulator shows that the curving is associated with a combination of opening and sliding along the previously placed hydraulic fracture, as well as the previous fracture's disturbance of the local stress field because of its propped width. Dimensional analysis and scaling techniques are used to identify the key parameters that are associated with suppression of each mechanism that can lead to hydraulic fracture curving. The analysis, which is in agreement with available data, results in a clarification of the conditions under which attractive and repulsive curving are expected, as well as the conditions under which curving is expected to be negligible or even completely suppressed. This last case of planar hydraulic fracture growth is of practical importance and will usually be considered desirable. We present a straightforward method for determining whether planar fracture growth is expected that additionally gives insight into how design parameters can be modified to promote planar hydraulic fracture growth.

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Section: Numerical Simulationmentioning

confidence: 99%

Parameters Effecting the Interaction among Closely Spaced Hydraulic Fractures

2011

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“…Therefore, more investigation is required to be done on the refracturing of a single horizontal well. Roussel and Sharma showed that the newly created fractures might initiate perpendicular to current fractures in the case of extreme stress reversal. Elbel and Mack concluded that, during production, the depletion in the direction of maximum horizontal stress is more than the depletion in the direction of minimum horizontal stress.…”

Section: Introductionmentioning

confidence: 99%

Analysis of refracturing in horizontal wells: Insights from the poroelastic displacement discontinuity method

Rezaei

Bornia

Rafiee³

et al. 2018

Num Anal Meth Geomechanics

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Summary In this paper, a fully coupled 2‐dimensional poroelastic displacement discontinuity method is used to investigate the refracturing process in horizontal wells. One of the objectives of refracturing is to access new reserves by adding new hydraulic fractures in zones that were bypassed in the initial fracturing attempt. Pore pressure depletion in the vicinity of old fractures directly affects the state of stress and eventually the propagation of newly created hydraulic fractures. Thus, a poroelastic analysis is required to identify guidelines for the refracturing process, in particular to understand the extension of the pore pressure depletion, and eventually, the orientation of new as well as old fractures. We propose a fully coupled approach to model the whole process of child fracture propagation in a depleted area between 2 parent fractures in the same wellbore. This approach omits the need of using multistep workflow that is regularly used to model the process. The maximum tensile stress criterion (σ criterion) is used for hydraulic fracture propagation. The proposed method is verified using available analytical solutions for total stress and pore pressure loading modes on a line fracture in drained and undrained conditions. Then, test cases of multifractured horizontal wells are studied to calculate the time evolution of the stress and pore pressure fields around old fractures and to understand the effect of these fields on the propagation path of newly created fractures. Finally, the effect of the pore pressure depletion on the propagation path of the newly created fractures in the bypassed area of the same wellbore is studied. The results show that the depleted areas around old fractures are highly affected by the extent and severity of the stress redistribution and pore pressure depletion. It is observed that a successful creation of new fractures may only happen in certain time frames. The results of this study provide new insights on the behavior of newly created fractures in depleted zones. They also clarify the relationship between stress change and pore pressure depletion in horizontal wells.

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“…First, the hydraulic fracture planes are not necessary aligned with the maximum horizontal stress, due to the presence of preexisting natural fractures and related fracture complexity. Second, nonuniform depletion due to heterogeneous permeability fields can cause stress reorientation and additional shear stress on the fracture planes due to poroelastic effects [26,27]. Third, some field operations, such as the failure of diversion during refracturing and undesired well connection when fracturing a new well (i.e., cross-well communication or frac-hit), can lead to fluid leakage into the preexisting hydraulic fractures which have been under depletion and result in additional slip on preexisting fractures [28].…”

Section: Introductionmentioning

confidence: 99%

Evolution of Friction and Permeability in a Propped Fracture under Shear

Zhang

Fang

Elsworth³

et al. 2017

Geofluids

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We explore the evolution of friction and permeability of a propped fracture under shear. We examine the effects of normal stress, proppant thickness, proppant size, and fracture wall texture on the frictional and transport response of proppant packs confined between planar fracture surfaces. The proppant-absent and proppant-filled fractures show different frictional strength. For fractures with proppants, the frictional response is mainly controlled by the normal stress and proppant thickness. The depth of shearingconcurrent striations on fracture surfaces suggests that the magnitude of proppant embedment is controlled by the applied normal stress. Under high normal stress, the reduced friction implies that shear slip is more likely to occur on propped fractures in deeper reservoirs. The increase in the number of proppant layers, from monolayer to triple layers, significantly increases the friction of the propped fracture due to the interlocking of the particles and jamming. Permeability of the propped fracture is mainly controlled by the magnitude of the normal stress, the proppant thickness, and the proppant grain size. Permeability of the propped fracture decreases during shearing due to proppant particle crushing and related clogging. Proppants are prone to crushing if the shear loading evolves concurrently with the normal loading.

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Role of Stress Reorientation in the Success of Refracture Treatments in Tight Gas Sands

Cited by 26 publications

References 29 publications

Parameters Effecting the Interaction among Closely Spaced Hydraulic Fractures

Parameters Effecting the Interaction among Closely Spaced Hydraulic Fractures

Analysis of refracturing in horizontal wells: Insights from the poroelastic displacement discontinuity method

Evolution of Friction and Permeability in a Propped Fracture under Shear

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