Method and instrument for analyzing starting pressure and remaining oil distribution of heterogeneous reservoir

Abstract

An instrument for heterogeneous reservoir starting pressure and remaining oil distribution comprises a displacement pump, a back-pressure pump and a heat preservation box, a three-way valve is arranged at the output end of the displacement pump, the other two paths of the three-way valve are connected with a simulated formation water container and a simulated crude oil container respectively, and multiple sets of core holders used in cooperation with branch pipelines are arranged in the heat preservation box. A return pressure gauge is arranged on an outlet of the return pressure solution container, an oil-water separator and a meter are arranged on the connecting pipeline, an outlet pressure gauge is arranged at the joint of an outlet of the core holder and the connecting pipeline, an inlet pressure gauge and an inlet flow meter are arranged on an inlet of the core holder, and an outlet pressure gauge and an inlet flow meter are arranged on the outlet of the core holder. The branch pipelines are respectively provided with an inching switch, the common pipeline I is provided with a switch, and the core holder is provided with an annular pressure pump.

Description

technical field [0001] The invention relates to the field of oil and natural gas exploration, in particular to a method and an instrument for analyzing the starting pressure and remaining oil distribution of heterogeneous reservoirs. Background technique [0002] In the process of modern oil reservoir development, the problem of reservoir heterogeneity has become an important restrictive factor restricting the development effect of oil and gas reservoirs, and its main influence is manifested in many aspects: [0003] One is that there are lithologies with large differences in seepage capacity in the reservoir. In the actual development process of water injection, gas injection or other supplementary formation energy, due to the difference in seepage capacity, some reservoirs strongly absorb water and other injected materials. However, some reservoirs absorb less water or can not absorb water or other injected substances at all, resulting in differences in the degree of crude...

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Problems solved by technology

[0003] One is that there are lithologies with large differences in seepage capacity in the reservoirs. During the actual development process of water injection, gas injection or other supplementary formation energy, due to the difference in seepage capacity, some reservoirs strongly absorb water and other injected materials. However, some reservoirs absorb less water or cannot absorb water or other injected substances at all, resulting in differences in the degree of crude oil production in the reservoirs, forming abundant remaining oil, and directly affecting the final extraction effect of crude oil;

[0004] The second is that due to the difference in seepage capacity, some reservoirs with poor seepage capacity, under the same injection pressure, almost all or most of the injected water or other injected substances are absorbed by the reservoirs with better seepage capacity. Better reservoirs form a larger pressure difference, and higher injection pressure may be required to produce reservoirs with poorer seepage capacity; however, higher injection pressures may lead to the direct formation of reservoirs with better seepage capacity "Water channeling" breakthroughs cause reserves loss in high-quality reservoirs. It is necessary to clarify the difference in start-up pressure and the specific pressure difference under which "channeling" breakthroughs are easy to form, so as to guide the reasonable injection methods and methods for reservoir development. injection pressure;

[0005] The third is that the heterogeneity in the reservoir may have an important impact on the multiphase seepage capacity of the reservoir, but there is no related research so far

In the traditional single-core sample analysis experiment, the oil-gas-water three-phase relative seepage capacity of the core sample is only limited by the reservoir characteristics of the core sample itself; in fact, the underground reservoir has serious heterogeneity, and a certain type of reservoir The oil-gas-water three-phase relative seepage capacity of a reservoir is not only limited by its own physical characteristics, but also very likely to be affected by other types of reservoirs around it: for example, if a high-quality reservoir For poor reservoirs, under the same injection pressure, there are important differences in the internal pressure gradient established by the two and the flow velocity of the internal fluid, resulting in a certain difference in seepage capacity when measured separately, especially for gas reservoirs. Large pressure gradient and large flow velocity will form gas turbulence, resulting in a decrease in meteorological relative permeability;

[0006] Fourth, the irreducible water and residual oil saturation of oil and gas reservoirs may be affected by effective stress

When the pore pressure of the reservoir decreases, the effective stress of the formation increases, and the irreducible water saturation and residual oil saturation change, resulting in a change in the actual recoverable reserves; The final producing situation of the reservoir is difficult to achieve the ideal state, that is, its residual oil saturation is inconsistent with the residual oil saturation analyzed in the independent experiment of this type of reservoir, and is generally much higher than the residual oil saturation measured alone, resulting in The actual mining effect becomes worse;

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