Low permeability fractured reservoir is a special reservoir with complex fracture distribution and dense matrix. Low permeability fractured reservoir always have small porosity, low pore pressure and permeability. Therefore, low permeability fractured reservoir has low oil recovery efficiency. Besides, the developing complex process and higher costs lead to lower economic benefit. Low permeability fractured reservoir production mechanisms in the fracture system mainly by the capillary force of water into the matrix. Therefore, the hydrophilic blocks of dense, self-priming effect of capillary water is the main mechanism of oil. In this study, numerical simulation, the establishment of a dual media model analysis showed that the capillary suction from the oil production rate and the final volume flow channel structure, the capillary force, viscosity of crude oil and other factors.
The speed of development of well test technology has been faster than well test interpretation technology in low permeability reservoirs. One of the main research directions for well test soft technology was specific interpretation theory and interpretation techniques. In recent years, well test was put forward higher request by the production complex and low permeability reservoirs. Test interpretation results urgently need to be applied to reservoir engineering analysis in-depth and quantitatively. One of the limited reality conditions of well test application was lack of the comprehensive research combined with the reservoir engineering. Combining with the test examples, the investigation radius change between injection-production wells was studied, and the build-up well test cycle in low permeability reservoir was optimized. According to the actual process situation, it was proposed that take 20d as the upper limit of well test cycle, and 10d block as the lower limit of well test cycle of build-up well test in a typical low permeability reservoir.
In order to further research in porous media tracer mass transfer diffusion rule based on experiment, the conventional displacement experiment of natural long cores were carried out and the effect of the heterogeneity of microscopic pores structure to tracer mass transfer diffusion was compared. The experiment results show that, when injection rate is close, because the heterogeneity of low permeability core pore structure is stronger and small-scale dash is existed, the output time will be earlier, concentration will rise slowly, and mixed coefficient will be bigger. In terms of the same permeability, because injection rate is low, the pressure difference of two ends is small, the start of porosity is wider and its quantity is less. Therefore, if inject less pore volume of multiples displacement fluid, the output will be present tracer, the pore network of so-called "channeling the effect" will be formed, and mixed constant will be bigger. In homogeneous core, when permeability is close, due to the injection rate increases which exacerbate the actually existed part of microscopic heterogeneity features of the internal core, the output time will be earlier, concentration will rise slowly.
The seepage mechanism of unconventional gas is very complex, and has a unique seepage mechanism and dynamic flow characteristics. It is difficult to use conventional gas production capacity to predict recoverable reserves. In this paper, starting from fluid mechanics, based on reservoir characteristics of the shale gas fracturing, a composite model of shale gas reservoirs was established, and stable production time was determined. We analyzed the effects of inside and outside zone permeability, the radius, pressure gradient, desorption influence of the compression factor and reservoir thickness, etc., and the established a shale gas well productivity equation refer to Vogel equation. The results show that: area permeability, penetration outside the area, zone radius, reservoir thickness and desorption compression factor were sensitive to shale gas production capacity; skin factor and the pressure gradient is not sensitive factor; through reliability analysis, the productivity formula which was referred to Vogel equation can determine the production capacity of shale gas wells quickly and accurately.
At present, test interpretation technology is still based on the rule and theory during 1960s-1980s, which wasn’t be developed and improved further in view of the new problems in field. The field practice and theory comparison have shown that these basic theory and interpretation model diverges obviously appropriate category, and have the singlet, unilateral problem of considered element, which can’t adapt to the quantification description of complex filtrate in porous medium. The basic theory and mathematic model of tracer test interpretation need to develop further, and interpretation means needs to improve corroboratively. From the point of numerical mathematics, the independent variables in reservoirs were found out and the objective function was constructed. Making use of improved real-number-style inheritance-arithmetic, the unitary parameters inversion and interpretation were accomplished in inter well tracer test.
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