scholarly journals Pressure transient analysis for hot water and two-phase geothermal wells: some numerical results

1980 ◽  
Author(s):  
S.K. Garg ◽  
J.W. Pritchett
Keyword(s):  
Transient Analysis ◽  
Numerical Results ◽  
Hot Water ◽  
Two Phase ◽  
Pressure Transient Analysis ◽  
Pressure Transient ◽  
Geothermal Wells

Pressure Transient Analysis for Two-Phase (Water/Steam) Geothermal Reservoirs

1980 ◽  
Vol 20 (03) ◽  
pp. 206-214 ◽  
Author(s):  
S.K. Garg
Keyword(s):  
Transient Analysis ◽  
Phase System ◽  
Well Testing ◽  
Two Phase ◽  
Pressure Transient Analysis ◽  
Water Steam ◽  
Pressure Transient ◽  
Geothermal Reservoirs ◽  
Diffusivity Equation ◽  
Phase Water

Pressure Transient Analysis for Two-Phase Pressure Transient Analysis for Two-Phase (Water/Steam) Geothermal Reservoirs Abstract A new diffusivity equation for two-phase (water/steam) flow in geothermal reservoirs is derived. The geothermal reservoir may be initially two-phase or may evolve into a two-phase system during production. Solutions of the diffusivity equation for a continuous line source are presented; the solutions imply that the plot of bottomhole pressure vs. loglot (t=time) should be a straight pressure vs. loglot (t=time) should be a straight line. The slope of the straight line is inversely proportional to the total kinematic mobility. proportional to the total kinematic mobility. Comparison of the theory with a limited number of computer-simulated drawdown histories shows excellent agreement. Introduction In petroleum engineering and groundwater hydrology, well tests are conducted routinely to diagnose the well's condition and to estimate formation properties. Well test data may be analyzed to yield quantitative information regarding (1) formation permeability, storativity, and porosity, (2) the presence of barriers and leaky boundaries, (3) the condition of the well (i.e., damaged or stimulated), (4) the presence of major fractures close to the well, and (5) the mean formation pressure. Well testing procedures (and the quality of information obtained) procedures (and the quality of information obtained) depend on the age of the well. During temporary completion, testing involves producing the reservoir using a temporary plumbing system (e.g., drillstem testing), and the estimates obtained for the formation parameters are not very accurate. After completion, parameters are not very accurate. After completion, testing usually is performed in the hydraulic mode. In hydraulic testing, one or more wells are produced at controlled rates, and pressure changes within the producing well itself or nearby observation wells producing well itself or nearby observation wells (interference tests) are monitored.A major concern of well testing is the interpretation of pressure transient data. Much of the existing literature deals with isothermal single-phase (water/oil) and isothermal two-phase (oil with gas in solution, free gas) systems. In general, there is a lack of methodology for analyzing nonisothermal reservoir systems, either single- or two-phase (water/steam). Geothermal reservoirs commonly involve nonisothermal two-phase flow during well testing. This paper presents a theoretical framework for analyzing multiphase pressure transient data in geothermal systems. Two-Phase Flow in Geothermal Systems Consider a fully penetrating well located in an infinite reservoir of thickness h. We neglect any variations in either formation or fluid properties in the vertical direction. (This is a common assumption in pressure transient analysis.) The geothermal system may be two-phase before production or may evolve into a two-phase system as a result of fluid production. In the latter case, a boiling front will production. In the latter case, a boiling front will propagate outward from the wellbore. The boiling propagate outward from the wellbore. The boiling front may be treated as a constant-pressure boundary (p=saturation pressure corresponding to the local reservoir temperature).For the sake of simplicity, consider a reservoir that is initially two-phase everywhere. Furthermore, it is convenient to assume that the pressure (and, hence, temperature) is uniform throughout the system. In radial geometry, the pressure response is governed by the following diffusivity equation (see Appendix for a derivation of Eq. 1). (1) SPEJ P. 206

Geothermal wells with water hammer during injection fall-off test: Numerical pressure transient analysis

Geothermics ◽  
2020 ◽  
Vol 87 ◽  
pp. 101838 ◽  
Author(s):  
Azhari S. Adiputro ◽  
Sadiq J. Zarrouk ◽  
Richard J. Clarke ◽  
Virginie Harcouët-Menou ◽  
Stijn Bos
Keyword(s):  
Transient Analysis ◽  
Water Hammer ◽  
Pressure Transient Analysis ◽  
Pressure Transient ◽  
Geothermal Wells

scholarly journals A Two-Phase Flow Model for Pressure Transient Analysis of Water Injection Well considering Water Imbibition in Natural Fractured Reservoirs

2018 ◽  
Vol 2018 ◽  
pp. 1-12
Author(s):  
Mengmeng Li ◽  
Qi Li ◽  
Gang Bi ◽  
Jiaen Lin
Keyword(s):  
Transient Analysis ◽  
Two Phase Flow ◽  
Fractured Reservoirs ◽  
Water Injection ◽  
Injection Well ◽  
Phase Flow ◽  
Two Phase ◽  
Pressure Transient Analysis ◽  
Pressure Transient ◽  
Water Imbibition

The pressure injection falloff test for water injection well has the advantages of briefness and convenience, with no effect on the oil production. It has been widely used in the oil field. Tremendous attention has been focused on oil-water two-phase flow model based on the Perrine-Martin theory. However, the saturation gradient is not considered in the Perrine-Martin method, which may result in errors in computation. Moreover, water imbibition is important for water flooding in natural fractured reservoirs, while the pressure transient analysis model has rarely considered water imbibition. In this paper, we proposed a semianalytical oil-water two-phase flow imbibition model for pressure transient analysis of a water injection well in natural fractured reservoirs. The parameters in this model, including total compressibility coefficient, interporosity flow coefficient, and total mobility, change with water saturation. The model was solved by Laplace transform finite-difference (LTFD) method coupled with the quasi-stationary method. Based on the solution, the model was verified by the analytical method and a field water injection test. The features of typical curves and the influences of the parameters on the typical curves were analyzed. Results show that the shape of pressure curves for single phase flow resembles two-phase flow, but the position of the two-phase flow curves is on the upper right of the single phase flow curves. The skin factor and wellbore storage coefficient mainly influence the peak value of the pressure derivatives and the straight line of the early period. The shape factor has a major effect on the position of the “dip” of pressure derivatives. The imbibition rate coefficient mainly influences the whole system radial flow period of the curves. This work provides valuable information in the design and evaluation of stimulation treatments in natural fractured reservoirs.

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