Tight sandstone core pore connectivity analysis method based on fluid injection

Abstract

The invention discloses a tight sandstone core pore connectivity analysis method based on fluid injection, which belongs to the technical field of digital core electrical simulation. The method comprises the following steps of S1, obtaining an X-CT three-dimensional grayscale image of a rock core, S2, carrying out saturation treatment on the rock core, so that a sodium iodide or potassium iodide solution is permeated into pores of the rock core, S3, acquiring an X-CT image of the rock core after saturation processing, S4, performing image registration on the X-CT image, S5, reconstructing a three-dimensional digital rock core according to the registered image, and S6, segmenting the three-dimensional digital rock core, and judging the pore connectivity through image comparison. According to the tight sandstone core pore connectivity analysis method based on fluid injection provided by the invention, the tight sandstone core is treated by using the sodium iodide or potassium iodide solution, so that the damage to the core is small, the imaging is clearer, and the pores which cannot be recognized under the CT resolution are clearly recognized; and accurate characterization of the pore connectivity and the connectivity mode in the tight sandstone reservoir is realized.

Description

technical field [0001] The invention relates to a method for analyzing the connectivity of pores in tight sandstone cores based on fluid injection, and belongs to the technical field of electrical simulation of digital cores. Background technique [0002] With the increasing demand for energy in the development of the national economy and the decreasing reserves of conventional oil and gas reservoirs, unconventional oil and gas resources have attracted more and more attention. Compared with conventional sandstone reservoirs, tight sandstone reservoirs have the characteristics of tight lithology, low porosity and low permeability, and low pressure coefficient of gas reservoirs. Tight sandstone reservoirs are rich in clay minerals. A large number of micro-nano pores and a small number of natural fractures are developed in clay, which are key parameters affecting the physical properties, permeability and electrical conductivity of tight sandstone reservoirs. Accurate evaluation...

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Problems solved by technology

But the cost of chloroauric acid is on the high side, and the solution is acidic, which is easy to cause skin and eye burns, and the operation risk is high; and the molecular weight of chloroauric acid is large, and the colloidal gold particles produced after the decomposition of chloroauric acid have uneven particle size and particle size. It is difficult to penetrate into the nano-scale pores in the tight sandstone clay, so the nano-scale pores in the tight sandstone cannot be marked by colloidal gold

In addition, the stability of microporous structure in clay in tight sandstone reservoirs is related to the sensitivity of infiltration fluid. External infiltration fluid entering clay may damage its internal microporous structure, for example, acidic infiltration fluid will cause clay to be eroded, or Causes the expansion of the micropore structure, which affects the accurate evaluation of the pore structure and pore connectivity in tight sandstone reservoirs

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