Transient flow to a finite-radius well with wellbore storage and skin effect in a poroelastic confined aquifer

Fan, Zhihua; Parashar, Rishi

doi:10.1016/j.advwatres.2020.103604

Cited by 24 publications

(17 citation statements)

References 43 publications

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“…The Laplace transform is an effective measure for solving Equation ( 6), and the Stehfest algorithm is widely adopted for reversing Laplace transform. For instance, Fan et al [37,38] adopted this method to deduce analytical solutions for pumping from a poroelastic, confined aquifer considering the effects of a finite-thickness skin zone and the wellbore storage. By using the Laplace transform for time t, the solution of the hydraulic head in the Laplace transform is (see the appendix for derivation)…”

Section: Discussionmentioning

confidence: 99%

An Analytical Solution for Non-Darcian Flow on a Constant Head Packer Test in the Interlayer Staggered Zone

et al. 2021

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Groundwater flow in an aquifer has frequently been found to be non-Darcian by performing in situ tests. A novel analytic model is proposed in this study for describing the unsteady non-Darcian flow in a confined aquifer by taking advantage of the observed flow rate and injection pressure during the constant head packer test. A linearization approximation of the Izbash equation is used to approximate the nonlinear term in the governing equation. This analytic model is applied to describe the non-Darcian flow in the interlayer staggered zone at the Baihetan hydropower station, China. The test results inversed by the genetic algorithm show that non-Darcian flow happened during the test under the injection pressure 0.3 MPa with the power index n is 1.278, non-Darcian hydraulic conductivity k 1 is 1.613 × 10 − 5 cm/s and the specific storage S s is 9.757 × 10 − 5 m-1, respectively. The sensitivity analysis indicated that when the power index n or the specific storage S s is larger, and the hydraulic head will increase more slowly and needs longer to stabilize, but the non-Darcian hydraulic conductivity k 1 shows the opposite trend. Moreover, the hydraulic head is more sensitive to the power index n compared to other parameters at late times. The findings of this study reveal the non-Darcian flow during the constant head packer test and provide a simple and fast way to estimate parameters for more accurate seepage field simulation.

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Section: Discussionmentioning

confidence: 99%

An Analytical Solution for Non-Darcian Flow on a Constant Head Packer Test in the Interlayer Staggered Zone

et al. 2021

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“…In practice, however, positive skin effects are more common. Such skin effects reduce the hydraulic conductivity in the near-well region [31][32][33][34][35][36][37][38][39][40][41]. Based on [9], it is possible to calculate the coefficient of additional resistances, W (skin factor), in the case of a real well, as in Equation ( 2).…”

Section: Additional Resistances (Skin Effect)mentioning

confidence: 99%

Software for Evaluating Pumping Tests on Real Wells

2021

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As the climate is changing, greater exploitation of groundwater reserves is becoming evident; however, this would have been apparent even without climate change. Therefore, increasing emphasis is given to maintaining well functionality. Wells are susceptible to aging, which reduces their efficiency. Today, there exist several solutions for determining the size of additional resistance (the skin effect), which indicates a well’s current state and that of its close surroundings. The implementation of most of these solutions is often time-consuming. To improve our tools, a goal has been set to accelerate and facilitate the method of determining the size of additional resistance. In this study, we present new software that accelerates this process. It applies an innovative method based upon a partial differential equation describing the radially symmetric flow to a real well, which occurs under an unsteady regime, using the Laplace transform. Stehfest algorithm 368 is used to invert the Laplace transform. Such software can be used to evaluate an additional-resistance well, even when a straight section evaluated using the Cooper–Jacob method is not achieved in the semilogarithmic plot of drawdown vs. log time during the pumping test. This solution is demonstrated in the comprehensive evaluation of 10 wells and 3 synthetic pumping tests.

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“…However, as the confining pressure increases, the relative change of pore pressure values decreases, meaning that the influence of pore fluid in the strength capacity of the sample declines. The product of the Skempton coefficient and Biot coefficient is described as the strength of poroelastic coupling [3,4].…”

Section: Introductionmentioning

confidence: 99%

“…For instance, [9] suggested a correlation for consolidated sediments as α = 1 − (1 − ϕ) 3.8 . (4) where ϕ represents the porosity. As another example, [10] introduced a similar correlation based on the tests on the dry rocks as…”

Section: Introductionmentioning

confidence: 99%

Empirical Formula for Dynamic Biot Coefficient of Sandstone Samples from South-West of Poland

Knez

Zamani

2021

Energies

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In this research, two empirical correlations have been introduced to calculate the dynamic Biot coefficients of low-porosity and high-porosity sandstone samples from two open pit mines located in South-West Poland. The experiments were conducted using an acoustic velocity measurement apparatus. Under the undrained condition, firstly, the confining pressure was increased in increments of 200 psi, and the values of pore pressure and dynamic elastic modulus were recorded. This experiment was continued until the Skempton coefficient remained in the range of 0.98–1. Secondly, an experiment on the same sample was conducted under drained conditions, and the corresponding dynamic elastic moduli were calculated. Then, using the calculated dynamic elastic moduli, the dynamic Biot coefficient was determined for each sample under different confining pressure. Finally, two empirical correlations were formulated for each sandstone category. The results demonstrate that, as the confining pressure increases, the Biot coefficient decreases from 0.79 to 0.50 and from 0.84 to 0.45 for low-porosity and high-porosity samples, respectively. Furthermore, as the porosity increases, the sandstone behavior increasingly approaches that of soil. The empirical correlations can be used for sandstone formations with the same porosity in projects where there is not a measurement method for the Biot coefficient.

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Transient flow to a finite-radius well with wellbore storage and skin effect in a poroelastic confined aquifer

Cited by 24 publications

References 43 publications

An Analytical Solution for Non-Darcian Flow on a Constant Head Packer Test in the Interlayer Staggered Zone

An Analytical Solution for Non-Darcian Flow on a Constant Head Packer Test in the Interlayer Staggered Zone

Software for Evaluating Pumping Tests on Real Wells

Empirical Formula for Dynamic Biot Coefficient of Sandstone Samples from South-West of Poland

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