Abstract
This paper presents a study of characteristic value method of well test analysis for horizontal gas well. Owing to the complicated seepage flow mechanism in horizontal gas well and the difficulty in the analysis of transient pressure test data, this paper establishes the mathematical models of well test analysis for horizontal gas well with different inner and outer boundary conditions. On the basis of obtaining the solutions of the mathematical models, several type curves are plotted with Stehfest inversion algorithm. For gas reservoir with closed outer boundary in vertical direction and infinite outer boundary in horizontal direction, while considering the effect of wellbore storage and skin effect, the pseudopressure behavior of the horizontal gas well can manifest four characteristic periods: pure wellbore storage period, early vertical radial flow period, early linear flow period, and late horizontal pseudoradial flow period. For gas reservoir with closed outer boundary both in vertical and horizontal directions, the pseudopressure behavior of the horizontal gas well adds the pseudosteady state flow period which appears after the boundary response. For gas reservoir with closed outer boundary in vertical direction and constant pressure outer boundary in horizontal direction, the pseudopressure behavior of the horizontal gas well adds the steady state flow period which appears after the boundary response. According to the characteristic lines which are manifested by pseudopressure derivative curve of each flow period, formulas are developed to obtain horizontal permeability, vertical permeability, skin factor, reservoir pressure, and pore volume of the gas reservoir, and thus the characteristic value method of well test analysis for horizontal gas well is established. Finally, the example study verifies that the new method is reliable. Characteristic value method of well test analysis for horizontal gas well makes the well test analysis process more simple and the results more accurate.
Highlights
Recent years have seen the ever-growing application of horizontal wells technology, which aroused considerable interest in the exploration of horizontal well test analysis [1,2,3,4]
This paper presents a study of characteristic value method of well test analysis for horizontal gas well
Odeh and Babu [9] indicated that four significant flow periods could be Mathematical Problems in Engineering observed during the process of horizontal well transient pressure behavior, which was further consolidated by the buildup and drawdown equations
Summary
Recent years have seen the ever-growing application of horizontal wells technology, which aroused considerable interest in the exploration of horizontal well test analysis [1,2,3,4]. For gas reservoir with closed outer boundary both in vertical and horizontal direction, according to (1), (2), (3), (5), and (7), the dimensionless bottomhole pseudopressure of horizontal gas well in the Laplace space can be obtained For gas reservoir with closed outer boundary in vertical direction and constant pressure outer boundary in horizontal direction, according to (1), (2), (3), (6), and (7), the dimensionless bottomhole pseudopressure of horizontal gas well in Laplace space can be obtained. Mathematical Problems in Engineering Figure 3: The schematic diagram of early vertical radial flow
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