Statistical Diagnosis (VEMST) of Flow Regime: Alternative to Pressure Derivative Approach in Pressure Transient Analysis—Part I

2009 ◽  
Author(s):  
Victor T. Biu ◽  
Emmanuel O. Biu ◽  
Mike O. Onyekonwu
2010 ◽  
Vol 13 (06) ◽  
pp. 845-860 ◽  
Author(s):  
Anh V. Dinh ◽  
Djebbar Tiab

Summary Hydraulic fracturing is an important well-stimulation technique that has been widely used in the oil and gas industry. Most of the pressure-transient-analysis techniques to analyze pressure responses of fractured wells are based on the assumption that the fracture is either vertical or horizontal. However, a hydraulic fracture could be inclined with a nonzero angle with respect to the vertical direction. Field studies have shown that most hydraulic fractures are not perfectly vertical. Thus, for an inclined hydraulic fracture, the vertical-orientation assumption may lead to erroneous results in welltest analysis, especially when the inclination angle is significant. However, there are very few studies concerning pressure-transient analysis of inclined hydraulic fractures, and there is no applicable well-test-analysis procedure available for inclined fractures. The purpose of this study is to develop a technique, on the basis of the pressure-derivative concept, for interpreting pressuretransient tests in wells with an inclined hydraulic fracture. Detailed analysis of unsteady-state pressure behavior of a fully penetrating inclined fracture in an infinite-slab reservoir was provided. Both uniform-flux and infinite-conductivity models were considered. The study has shown that inclined-fracture pressure data exhibit flow regimes similar to those for vertical fractures. Those flow regimes are linear and pseudoradial flow for both uniform-flux and infinite-conductivity models. However, for the infinite-conductivity model, a biradial- (or elliptical) flow regime is also observed. In the case of a high formation-thickness/fracture-half-length ratio and high angle of inclination, both uniform-flux and infiniteconductivity inclined-fracture models exhibit an additional flow regime, called early radial (ER) flow in this paper. This ER-flow regime for an inclined hydraulic fracture has not been mentioned in the literature before. A type-curve-matching technique was developed in this study using both pressure and pressure-derivative curves. This typecurve-matching procedure can be used to obtain the following parameters: fracture half-length, inclination angle, formation permeability, and the pseudoskin factor. The results should be verified with other pressure plots such as the semilog plot of vs. t and the Δp-vs.-t1/2 plot. A set of type curves with associated data was also provided for uniform-flux and infinite-conductivity inclined- fracture models. Detailed explanations, tables, figures, and a numerical example are included in this paper.


2017 ◽  
Vol 35 (2) ◽  
pp. 194-217 ◽  
Author(s):  
Zhang Wei ◽  
Jiang Ruizhong ◽  
Xu Jianchun ◽  
Gao Yihua ◽  
Yang Yibo

In this paper, the mathematical model of production performance analysis for horizontal wells in composite coal bed methane reservoir is introduced. In this model, two regions with different formation parameters are distinguished, and multiple mechanisms are considered including desorption, diffusion, and viscous flow. Then the solution of horizontal well performance analysis model is obtained by using point source function method, Laplace transform, and Stehfest algorithm comprehensively. The solution of the proposed model is verified with previous work thoroughly. The pressure transient analysis for horizontal well when producing at a constant rate is obtained and discussed. At last, different flow regimes are divided based on pressure transient analysis curves. They are early wellbore storage period, skin factor period, first radial flow regime, transition regime, second radial flow regime, transfer regime, and late pseudo-radial flow regime. The effects of related parameters such as storativity ratio, transfer coefficient, adsorption coefficient, ratio of vertical permeability to horizontal permeability, skin factor, horizontal well position in vertical direction, and inner region radius are analyzed as well according to pressure transient analysis and rate transient analysis curves. The presented work in this paper can give a better understanding of coal bed methane production performance in composite reservoir.


Author(s):  
Hussein Al- Ali

This work is discussed how to differentiate between two tricky models for sand stone formation by using the pressure transient analysis PTA for three Wells which are distributed in south, middle and north of X field. In the derivative curve these two models have the same sequence of flow regime which are by hump, first radial flow regime, transition hump and then late radial flow regime. The parameter Kappa (K) played the most important key to select the type of reservoir model and differentiate between the two models in PTA. In the middle and south of the field, this parameter has a value close to one at well no. Rt-16 & Rt-18, which means that the system behaves as dual porosity. On the other hand, Kappa has a value of around (0.74) in Rt-17 to represent a double permeability system but without cross flow between two layers due to the small value of Lamda.


2017 ◽  
Author(s):  
M. Ibrahim ◽  
C. Pieprzica ◽  
E. Vosburgh ◽  
A. Dabral ◽  
O. Olayinka ◽  
...  

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