Abstract
Two-phase flow behavior in fractured carbonate reservoirs was investigated due to the importance for geothermal and petroleum resource recovery, such as in this study the phase change of volatile oil. This paper presents a semi-analytical method for accurately modeling two-phase flow behavior and quickly predicting the production performance. The fractured carbonate reservoir was modeled with a dual-porosity model, and the phase change and two-phase flow were modeled using the black oil model. The production of the oil phase was obtained through linearizing and solving the mathematical model. The gas phase production was forecast using the producing gas-oil ratio (GOR), calculated using flowing material balance equations. By comparing the semi-analytical solution to the solution of the commercial numerical simulator and applying it to a field case, the accuracy and practicability of the proposed semi-analytical method could be validated. Based on the semi-analytical model, the influences of several critical parameters on production performance were also analyzed. The proposed model was shown to be efficient in evaluating two-phase production performance of horizontal volatile oil wells. Furthermore, the new technique is able to serve as a useful tool for analyzing two-phase production data and making forecasts for volatile oil wells in fractured carbonate reservoirs.
Highlights
With the degree of deepening exploration and adoption of advanced technology, the exploitation of fractured carbonate volatile oil reservoirs has been attracting considerable attention in recent years [1,2,3,4]
A big challenge is that the phase change, pressure dependent properties, and two-phase flow behavior and stress-dependent fracture permeability should be all considered when developing the mathematical model of fractured carbonated volatile oil reservoirs
The results show that the interpreted horizontal wellbore length and fracture permeability are 580 m and 2.6 mD
Summary
With the degree of deepening exploration and adoption of advanced technology, the exploitation of fractured carbonate volatile oil reservoirs has been attracting considerable attention in recent years [1,2,3,4]. The application of horizontal wells increases the drainage area and enhances production of a single well. The two-phase flow of oil and gas is quite common and hard to simulate in volatile oil reservoirs. The fractured carbonate volatile oil reservoir is rather complicated because of its complex reservoir architecture and fluid properties. A big challenge is that the phase change, pressure dependent properties, and two-phase flow behavior and stress-dependent fracture permeability should be all considered when developing the mathematical model of fractured carbonated volatile oil reservoirs. It is crucial to predict the production and analyze two-phase production data from this kind of well, and much research has been done on theoretical models of horizontal wells in fractured carbonate reservoirs [13,14,15,16,17]. Most of them are only applicable to the single-phase
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