Calculation method for low permeability reservoir flooding information of fluid replacement

Abstract

The present invention discloses a calculation method for low permeability reservoir flooding information of fluid replacement. The method comprises: 1) acquiring response features of logging before and after reservoir flooding in a region, and selecting, from the response features, natural gamma GR and acoustic interval transit time AC logging curves without significant lithological and physical changes before and after flooding; 2) selecting logging information of a model well that is not flooded, and establishing a function relationship among electrical resistivity of an original fluid in reservoir pores, natural gamma and acoustic interval transit time; 3) calculating a flooded model well in the region by using the function relationship to obtain the electrical resistivity t1 of the original fluid contained in the reservoir pores in the flooded model well, and comparing the electrical resistivity t1 with electrical resistivity t2 obtained by actual measurement to obtain an electrical resistivity variation value; 4) establishing a dividing standard of identifying a flooding level by using the electrical resistivity variation value delta Rt; and 5) according to the dividing standard of identifying the flooding level by using the electrical resistivity variation value delta Rt, established in the step 4), accurately and effectively determining flooding information of a to-be-evaluated well in the region.

Description

technical field [0001] The invention belongs to the technical field of petroleum logging, and relates to a method for calculating water-out information of a fluid-replaced low-permeability oil reservoir. Background technique [0002] The target reservoir in the study area has poor physical properties and small storage space. The porosity distribution ranges from 4 to 16%, and the permeability is mainly distributed in the range of 0.1 to 2×10. -3 μm 2 It belongs to low porosity and low permeability reservoirs. After more than 20 years of water flooding development, the fluid properties, pore structure and oil-water distribution of the reservoir have changed. With the increase of water content, the flooding situation is complex, the electrical changes are getting bigger and bigger, and it is difficult to identify the flooding level. Accurate division of water flooding level is a problem that must be solved in the adjustment of waterflooding oilfields, and plays a vital role...

AI Technical Summary

Problems solved by technology

At present, there are many methods for evaluating the water flooding level of water flooded formations, such as qualitative identification method of well logging curves, intersection chart method and movable fluid analysis method, etc. All have regional limitations, and there is no general fast and qualitative calculation method for water flooding information of low-permeability reservoirs, which is difficult to popularize and apply

Reconstructing the resistivity of the original formation in the water-flooded zone is one of the effective methods to quickly and qualitatively divide the water-flooding level. However, due to the lack of data in this area, and the reconstruction methods are mostly established based on a large number of core experiment data, they are limited by expensive coring costs. Due to limitations and lack of core experimental analysis data, the scope of application is not large, especially in the secondary development of old oilfield areas, it is difficult to meet the actual production needs

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