On the determination of the skin factor and the turbulence term coefficient through a single constant gas pressure test

Rangel-German, Edgar; Samaniego, Fernando

doi:10.1016/s0920-4105(00)00026-7

Cited by 12 publications

(6 citation statements)

References 9 publications

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“…These effects are called non-Darcy effects, because they make the flow deviate from the Darcy's law. These non-Darcy effects significantly influence gas production performance in a fractured well 15,16,17 . These effects can be taken into account by adding a non-Darcy component to the usual Darcy's equation, which leads to the Forchheimer's equation.…”

Section: Non-darcy Effects During Transient Flow Periodmentioning

confidence: 99%

An Analytical Model for Production Estimation from Hydraulically Fractured Tight-Gas Reservoirs

Rahman¹,

Rahman²,

Rahman³

2002

Proceedings of SPE Asia Pacific Oil and Gas Conference and Exhibition

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TX 75083-3836, U.S.A., fax 01-972-952-9435. AbstractIn relatively high-permeability reservoirs, the pseudo-steady state (PSS) flow condition dominates the production life of a well, and therefore modeling of production profile considering this flow condition only is found adequate. In tight-gas reservoirs, however, the early production period is dominated by the transient flow condition whereas the later period by the PSS condition. Neither of these conditions alone can be used to adequately model the production profile during the entire production life of a tight-gas reservoir. The creation of hydraulic fracture also influences the flow conditions and thus the production profile. This paper presents an analytical method, which combines both the flow conditions and account for the effect of hydraulic fracture and non-Darcy components for computationally efficient estimation of production from tight-gas reservoirs. An algorithm is then presented to couple these two different models by a production rate matching technique, which has resulted in a hybridized transientpseudo-steady-state (TPSS) model to predict the production profile during the whole production life. The production profiles and resulting pressure profiles for both TPSS and PSS models are verified by a reservoir simulator for a range of reservoir permeability. The TPSS model is found to be closer to the results from simulation for low-permeability reservoirs.

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Section: Non-darcy Effects During Transient Flow Periodmentioning

confidence: 99%

An Analytical Model for Production Estimation from Hydraulically Fractured Tight-Gas Reservoirs

Rahman¹,

Rahman²,

Rahman³

2002

Proceedings of SPE Asia Pacific Oil and Gas Conference and Exhibition

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“…The non-Darcy effects significantly influence gas production performance 2,3,4 . Since then much work has been covered to address non-Darcy effects.…”

Section: Introductionmentioning

confidence: 99%

Productivity Prediction for Fractured Wells in Tight Sand Gas Reservoirs Accounting for Non-Darcy Effects

Rahman

2008

All Days

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Reliable prediction of production profile for fractured wells is important for hydraulic fracturing optimization. Contribution of Russian researchers (Hristianovich, Zheltov, Goldstein, Entov) in hydraulic fracturing is worldwide recognized. The production profile includes early transient period that is followed by pseudo-steadystate production. Usually, the transition period for conventional reservoirs lasts for months while for tight sands with permeabilities far below millidarcy, it can exceed years. Therefore, two regimes are important for production profile prediction in tight sand reservoirs.Drawdown values in tight sands significantly exceed those for conventional reservoirs, so gas velocity in well fractures is also exceedingly higher. At high Reynolds numbers, inertia effects have the same order of magnitude that the viscous (Darcy's) pressure losses. It results in well productivity decrease. Therefore, it is important to account for non-Darcy effects in fractured well modelling.In the current paper, the inertia non-Darcy pressure losses are incorporated in the mathematical model for gas production via fractured well in tight sand reservoirs by including the quadratic term into momentum balance equation for gas flow in fracture. The model is based on matching of semi-analytical solutions for transient and pseudo-steady-state flows towards well and extends the previous research by considering non-Darcy effects. The iterative procedure allows predicting production profile up to 15 years in fields with permeability 0.005-0.2 md. The model developed aims optimization of hydraulic fracturing in tight sand gas fields.

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“…Transient analysis of gas wells producing at constantbottomhole pressure from low-permeability reservoirs have been also discussed in the literature by Berumen et al, 15,16 Vega et al, 17 Camacho et al, 18 and Rangel-German and Samaniego. 19 Transient constant-pressure performance of gas wells depends on fluid and reservoir properties, formation damage or stimulation, wellbore storage, and turbulent flow in the vicinity of the wellbore caused by high velocity production.…”

Section: Introductionmentioning

confidence: 99%

An Investigation of Gas Well Testing Under Constant-Bottomhole Pressure Conditions, High-Velocity Flow Effects, and Formation Damage

et al. 2003

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TX 75083-3836, U.S.A., fax 01-972-952-9435. AbstractThis paper presents an investigation of the validity of applying the constant-pressure liquid solution to transient ratedecline analysis of gas wells. Pseudo-pressure, non-Darcy flow effects, and formation damage are incorporated in the liquid solution to simulate actual real gas flow in the vicinity of the wellbore. The study shows that for constant-bottomhole pressure gas production the conventional semilog plot of the inverse of the dimensionless rate versus the dimensionless time used for liquid solution has to be modified to consider the high-velocity flow effects. This is especially true when the reservoir permeability is higher than 1 md and the well test is affected by non-Darcy flow and formation damage. This paper also presents a novel systematic method to determine the formation permeability, mechanical skin factor, and non-Darcy flow coefficient from a single constantpressure production test. The working equations are written in such a way that allows a graphical analysis of the variable rate with time that is analogous to the analysis of constant-rate production test. The analysis procedure is simple and straightforward. It does not require type-curve matching or correlations. The applicability of the proposed method is illustrated using several simulated examples. The input formation permeability varies from a low value of 0.1 md to a high value of 5 md. The ratio of the downhole pressure to the initial reservoir pressure ranges from 0.1 to 0.8.

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On the determination of the skin factor and the turbulence term coefficient through a single constant gas pressure test

Cited by 12 publications

References 9 publications

An Analytical Model for Production Estimation from Hydraulically Fractured Tight-Gas Reservoirs

An Analytical Model for Production Estimation from Hydraulically Fractured Tight-Gas Reservoirs

Productivity Prediction for Fractured Wells in Tight Sand Gas Reservoirs Accounting for Non-Darcy Effects

An Investigation of Gas Well Testing Under Constant-Bottomhole Pressure Conditions, High-Velocity Flow Effects, and Formation Damage

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