Method for quantitatively evaluating influence of supercritical carbon dioxide injection on pore throat structure of low-permeability sandstone oil reservoir
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A technology for carbon dioxide and sandstone reservoirs, applied in permeability/surface area analysis, measurement devices, water resources assessment, etc., can solve problems that do not involve quantitative evaluation, and achieve the effect of maintaining the original characteristics and authentic experimental results
Active Publication Date: 2018-04-10
XI'AN PETROLEUM UNIVERSITY
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None of the above methods or techniques involve supercritical CO 2 Contents of Quantitative Evaluation of Injection Effect on Pore Throat Structure of Low Permeability Sandstone Reservoir
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Embodiment 1
[0050] A quantitative evaluation method for the impact of supercritical carbon dioxide injection on the pore throat structure of low-permeability sandstone reservoirs, including the following steps:
[0051] Step 1. Core preparation: drill a core from the full-diameter core, with a diameter of 2.5 cm and a length of 3.8 cm, wash with oil and dry, and the gas permeability of the core is 1.323×10 -3 μm 2 ; Prepare the working fluid, in order to remove the influence of ion precipitation on the pore throat structure, use distilled water without ions to simulate formation water;
[0052] Step 2, vacuumize and saturate with distilled water, calculate the core porosity to be 11.21%, and the pore volume to be 2.14ml;
[0053] Step 3: Measure the NMR T of the core before and after centrifugation 2 Spectrum;
[0054] Step 4. Since the core has been centrifuged, it is necessary to re-saturate distilled water;
[0055] Step 5. Place the core sample in the core holder and connect the C...
Embodiment 2
[0065] A quantitative evaluation method for the impact of supercritical carbon dioxide injection on the pore throat structure of low-permeability sandstone reservoirs, including the following steps:
[0066] Step 1. Core preparation: drill a core from a full-diameter core, with a diameter of 2.5 cm and a length of 3.8 cm, wash with oil and dry, and the gas permeability of the core is 0.137×10 -3 μm 2 ;Prepare the working solution, according to the water type analysis results in the research area, use 20000mg / L CaCl 2 The solution simulates formation water;
[0067] Step 2: Vacuumize and saturate CaCl 2 solution, the calculated core porosity is 7.27%, and the pore volume is 1.36ml;
[0068] Step 3: Measure the NMR T of the core before and after centrifugation 2 Spectrum;
[0069] Step 4. Since the core has been centrifuged, it needs to be resaturated with CaCl 2 solution;
[0070] Step 5. Place the core sample in the core holder and connect the CO 2 Flooding process, se...
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Abstract
The invention discloses a method for quantitatively evaluating the influence of supercritical carbon dioxide injection on the pore throat structure of a low-permeability sandstone oil reservoir. Firstly, a rock core is prepared and a working fluid is prepared; then the rock core is vacuumized, and saturated with the working fluid, and porosity and pore volume of the rock core are measured; NMR T2spectra is measured, and irreducible water saturation is measured centrifugally; the rock core is saturated with the working fluid again; supercritical carbon dioxide is injected under the conditionsof temperature of 70 DEG C and return pressure of 8 MPa; the rock core is dried, vacuumized, and saturated with the working fluid; the NMR T2 spectra is measured, and the irreducible water saturationis measured centrifugally; the NMR T2 spectra before the supercritical carbon dioxide injection and the NMR T2 spectra after the supercritical carbon dioxide injection are converted into pore throat radiuses, and a pore throat distribution curve is drawn; and the influence of the supercritical carbon dioxide injection on a movable hole throat area and the pore throat structure before the supercritical carbon dioxide injection, after the supercritical carbon dioxide injection and at different time of the supercritical carbon dioxide injection can be can be quantitatively compared and evaluated.The method can quantitatively and accurately evaluate the influence of the supercritical carbon dioxide injection on the pore throat structure of the low-permeability sandstone oil reservoir.
Description
technical field [0001] The invention belongs to the technical field of oil and gas field development, and in particular relates to a quantitative evaluation method for the influence of supercritical carbon dioxide injection on the pore throat structure of low-permeability sandstone reservoirs. Background technique [0002] Low-permeability reservoirs are widely distributed in my country, and tight oil production will play a pivotal role in China's future oil and gas production, and will become one of the new mainstays for increasing China's oil and gas reserves and production in the future. Compared with water injection and other gas injection, CO 2 The main advantage is that it is easy to reach the supercritical state. When the temperature is 31.26℃ higher than the critical temperature and the pressure is 7.2MPa higher than the critical pressure, CO 2 In a supercritical state, its properties will change, its density is close to that of liquid, its viscosity is close to th...
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