Pressure Transient Response in Stress-Sensitive Formations

Multistage fractured horizontal wells (MFHWs) have become the main technology for shale gas exploration. However, the existing models have neglected the percolation mechanism in nanopores of organic matter and failed to consider the differences among the reservoir properties in different areas. On that account, in this study, a modified apparent permeability model was proposed describing gas flow in shale gas reservoirs by integrating bulk gas flow in nanopores and gas desorption from nanopores. The apparent permeability was introduced into the macroseepage model to establish a dynamic pressure analysis model for MFHWs dual-porosity formations. The Laplace transformation and the regular perturbation method were used to obtain an analytical solution. The influences of fracture half-length, fracture permeability, Langmuir volume, matrix radius, matrix permeability, and induced fracture permeability on pressure and production were discussed. Results show that fracture half-length, fracture permeability, and induced fracture permeability exert a significant influence on production. A larger Langmuir volume results in a smaller pressure and pressure derivative. An increase in matrix permeability increases the production rate. Besides, this model fits the actual field data relatively well. It has a reliable theoretical foundation and can preferably describe the dynamic changes of pressure in the exploration process.

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“…is defined as = ( /2 ) , where = exp(− Δ ). Pedrosa's substitution [43] is used to weaken the nonlinearity of (19). By setting…”

Section: Mathematical Modelmentioning

confidence: 99%

A Mathematical Pressure Transient Analysis Model for Multiple Fractured Horizontal Wells in Shale Gas Reservoirs

et al. 2018

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“…It's not difficult to find that the macro-fracture equation contains strong nonlinear, the perturbation technology and the Presoda transformation are applied to linearize this equation [20], the formula is as follows:…”

Section: Mathematical Modelmentioning

confidence: 99%

“…Samaniego VF et al (1980), Raghavan et al (2004) employed simulation and experiment methods to make some research about the impact of stress sensitivity on the conventional reservoirs [18,19]. Pedrosa et al (1986) first applied the mathematical method to study the stress sensitivity for homogeneous and dual-porosity reservoirs [20]; Wang (2013) develop a dual porosity spherical flowing model with consideration of the stress sensitivity in micro-fractures for shale gas reservoirs [21].…”

Section: Introductionmentioning

confidence: 99%

Productivity Model for Shale Gas Reservoir with Comprehensive Consideration of Multi-mechanisms

Deng¹,

Guo²,

Tian³

et al. 2015

TOPEJ

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Multi-stage fracturing horizontal well currently has been proved to be the most effective method to produce shale gas. This method can activate the natural fractures system defined as stimulated reservoir volume (SRV), the remaining region similarly is defined as un-stimulated reservoir volume (USRV). At present, no type curves have been developed for hydraulic fractured shale gas reservoirs in which the SRV zone has triple-porosity dual-depletion flow behavior and the USRV zone has double porosity flow behavior. In this paper, the SRV zone and USRV zone respectively are simplified as cubic triple-porosity and slab dual porosity media. We have established a new productivity model for multifractured horizontal well shale gas with Comprehensive consideration of desorption, diffusion, viscous flow, stress sensitivity and dual-depletion mechanism in matrix. The rate transient responses are inverted into real time space with stehfest numerical inversion algorithm. Type curves are plotted, and different flow regimes in shale gas reservoirs are identified. Effects of relevant parameters are analyzed as well. The whole flow period can be divided into 8 regimes: bilinear flow in SRV; pseudo elliptic flow; dual inter-porosity flow; transitional flow; linear flow in USRV; inter-porosity flow and boundary-dominated flow. The stress sensitivity basically has negative influence on the whole productivity period .The less the value of Langmuir volume and the lager the value of Langmuir pressure, the more lately the inter-porosity flow and boundary-dominated flow occurs. It in concluded that the USRV zone has positive influence on production and could not be ignored.

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“…In the aspect of transient model analysis (pressure or rate), lots of scholars have paid attention to the stress-dependent permeability [5][6][7] . Dealing with the nonlinearity of the seepage differential equation, it is commonly based on the Pedrosa's linearization and perturbation technique [8][9][10] . Through the above literature summarization, we expect to figure out the transient model of natural gas produced by a horizontal well.…”

Section: Introductionmentioning

confidence: 99%

Hydromechanics Model of Natural Gas Transport in Stress-sensitive Dual-porosity Medium

Cao¹,

Lu²,

Li³

et al. 2018

dtetr

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Abstract. The assumption of constant permeability is not strictly applicable to porous media where rock properties undergo changes, such as stress-sensitive gas reservoirs. This study developed a hydromechanics model of a horizontal well in dual-porosity media considering the stress-sensitivity effect. The solution methods include variable substitution, perturbation technique, Laplace transformation, Sturm-Liouville eigenvalue theory, orthogonal transformation and numerical inversion. The results showed that the production rate decreases with the increasing of permeability modulus and the derivative curve will be warped up during the whole system late radial flow stage. The research has both theoretical and practical significance in predicting production performance and evaluating underground fluid transport in such formations.

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Pressure Transient Response in Stress-Sensitive Formations

Cited by 229 publications

References 4 publications

A Mathematical Pressure Transient Analysis Model for Multiple Fractured Horizontal Wells in Shale Gas Reservoirs

A Mathematical Pressure Transient Analysis Model for Multiple Fractured Horizontal Wells in Shale Gas Reservoirs

Productivity Model for Shale Gas Reservoir with Comprehensive Consideration of Multi-mechanisms

Hydromechanics Model of Natural Gas Transport in Stress-sensitive Dual-porosity Medium

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