Method for quantitatively evaluating oil content of continental lake basin low-porosity tight oil reservoir

Abstract

The invention provides a method for quantitatively evaluating the oil content of a continental lake basin low-porosity tight oil reservoir. The method comprises the following steps: determining pore size distribution R original of a to-be-measured reservoir rock core; determining minimum pore throat diameter by using the Roriginal so as to determine the maximum breakthrough pressure and the formation temperature, and determining fluid content VAfluid and the oil content VAoil of the to-be-measured reservoir rock core under the temperature and pressure so as to represent the fluid content and the oil content of all pores, including communicating pores and non-communicating pores, of the to-be-measured reservoir rock core; determining breakthrough pressure and formation temperature corresponding to the median pore throat diameter by using the Roriginal, and determining fluid content VBfluid and oil content VBoil of the to-be-measured reservoir rock core under the temperature and pressureto represent the fluid content and oil content of the communicating pores of the to-be-measured reservoir rock core; and according to the VAfluid, the VAoil, the VBfluid and the VBoil, determining the oil saturation of the communicating pores, the oil saturation of the non-communicating pores and the total oil saturation to realize quantitative evaluation of the oil content of the continental lake basin tight oil.

Description

technical field [0001] The invention relates to a method for evaluating the oil content of tight oil reservoirs in continental lake basins, in particular to a method for quantitatively evaluating the oil content of connected and unconnected pores of tight oil reservoirs. Background technique [0002] Various types of unconventional oil and gas resources are developed in continental lacustrine basins, and oil shows the law of in-situ accumulation, adjacent enrichment, and integrated accumulation (Zou Caicai et al., Unconventional Petroleum Geology [M], 2011). Reservoirs include not only tight sandstone, tight limestone, and tight diamictite, but also shale reservoirs dominated by nano-pore throats. Crude oil not only exists in connected pores such as micron-scale intergranular dissolution pores and microcracks, but also enriches in intragranular pores with poor connectivity (Bai Bin, Zhu Rukai, Wu Songtao, etc. Microscopic pore throat structure of unconventional oil and gas t...

AI Technical Summary

Problems solved by technology

In particular, the method of measuring oil saturation by nuclear magnetic resonance logging is simple and convenient, and the time required is short, which solves the problems of long period and complicated process of other current methods of measuring oil saturation

When magnetic resonance technology is used to measure the oil saturation of conventional reservoirs, the pores are mostly connected pores, and the saturated MnCl 2 Solution method, the measured pore volume and oiliness can fully reflect the real characteristics, but for low-porosity tight oil reservoirs or shale, the saturated fluid is only rich in connected pores, which are not connected under different temperatures and pressures under the constraints of geological conditions With large pore volume, there will be large deviations in the determination of oil saturation, which cannot satisfy the accurate evaluation of oiliness of tight (shale) oil

Images