CN116660305B - Based on nuclear magnetism T 2 Method for measuring full-pore-size distribution of shale oil reservoir core of spectrum - Google Patents
Based on nuclear magnetism T 2 Method for measuring full-pore-size distribution of shale oil reservoir core of spectrum Download PDFInfo
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- 238000001228 spectrum Methods 0.000 title claims abstract description 100
- 238000009826 distribution Methods 0.000 title claims abstract description 98
- 230000005311 nuclear magnetism Effects 0.000 title claims abstract description 54
- 238000000034 method Methods 0.000 title claims abstract description 42
- 239000003079 shale oil Substances 0.000 title claims abstract description 20
- 229920006395 saturated elastomer Polymers 0.000 claims abstract description 67
- 238000012360 testing method Methods 0.000 claims abstract description 55
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Chemical compound O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 54
- XLYOFNOQVPJJNP-ZSJDYOACSA-N Heavy water Chemical compound [2H]O[2H] XLYOFNOQVPJJNP-ZSJDYOACSA-N 0.000 claims abstract description 28
- DIOQZVSQGTUSAI-UHFFFAOYSA-N decane Chemical compound CCCCCCCCCC DIOQZVSQGTUSAI-UHFFFAOYSA-N 0.000 claims abstract description 22
- 238000003825 pressing Methods 0.000 claims abstract description 20
- 238000010521 absorption reaction Methods 0.000 claims abstract description 17
- 238000001035 drying Methods 0.000 claims abstract description 16
- 239000012153 distilled water Substances 0.000 claims abstract description 11
- 238000009738 saturating Methods 0.000 claims abstract description 11
- 239000012530 fluid Substances 0.000 claims abstract description 10
- 239000011148 porous material Substances 0.000 claims description 52
- 238000005213 imbibition Methods 0.000 claims description 36
- QSHDDOUJBYECFT-UHFFFAOYSA-N mercury Chemical compound [Hg] QSHDDOUJBYECFT-UHFFFAOYSA-N 0.000 claims description 27
- 229910052753 mercury Inorganic materials 0.000 claims description 27
- 238000006243 chemical reaction Methods 0.000 claims description 25
- 239000011435 rock Substances 0.000 claims description 15
- 238000004458 analytical method Methods 0.000 claims description 11
- 238000005481 NMR spectroscopy Methods 0.000 claims description 10
- 238000012800 visualization Methods 0.000 claims description 10
- 238000011545 laboratory measurement Methods 0.000 claims description 9
- 230000003068 static effect Effects 0.000 claims description 9
- 238000004364 calculation method Methods 0.000 claims description 8
- 239000007788 liquid Substances 0.000 claims description 7
- 238000005303 weighing Methods 0.000 claims description 6
- 238000002347 injection Methods 0.000 claims description 4
- 239000007924 injection Substances 0.000 claims description 4
- 230000001419 dependent effect Effects 0.000 claims description 3
- 230000004907 flux Effects 0.000 claims description 3
- 238000012512 characterization method Methods 0.000 abstract description 5
- 230000005389 magnetism Effects 0.000 abstract 2
- 230000000007 visual effect Effects 0.000 description 27
- 229920001971 elastomer Polymers 0.000 description 4
- 239000004927 clay Substances 0.000 description 2
- 230000006378 damage Effects 0.000 description 2
- 238000010586 diagram Methods 0.000 description 2
- 238000002156 mixing Methods 0.000 description 2
- 238000002459 porosimetry Methods 0.000 description 2
- 238000011160 research Methods 0.000 description 2
- 238000001179 sorption measurement Methods 0.000 description 2
- 230000000694 effects Effects 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 238000000605 extraction Methods 0.000 description 1
- 238000000445 field-emission scanning electron microscopy Methods 0.000 description 1
- 238000005259 measurement Methods 0.000 description 1
- 239000003208 petroleum Substances 0.000 description 1
- 230000000704 physical effect Effects 0.000 description 1
- 239000011343 solid material Substances 0.000 description 1
- 238000003860 storage Methods 0.000 description 1
- 238000009736 wetting Methods 0.000 description 1
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N24/00—Investigating or analyzing materials by the use of nuclear magnetic resonance, electron paramagnetic resonance or other spin effects
- G01N24/08—Investigating or analyzing materials by the use of nuclear magnetic resonance, electron paramagnetic resonance or other spin effects by using nuclear magnetic resonance
- G01N24/081—Making measurements of geologic samples, e.g. measurements of moisture, pH, porosity, permeability, tortuosity or viscosity
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- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02A—TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE
- Y02A90/00—Technologies having an indirect contribution to adaptation to climate change
- Y02A90/30—Assessment of water resources
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Abstract
The invention relates to a nuclear magnetism-based T 2 The method for determining the full-aperture distribution of the shale oil reservoir core of the spectrum comprises the steps of drying the core of the shale oil reservoir core, and carrying out nuclear magnetism T 2 Spectrum test to determine core dry sample T 2 Spectrum P in The method comprises the steps of carrying out a first treatment on the surface of the The core of coring is saturated with distilled water, and nuclear magnetism T is carried out 2 Spectrum test to determine saturated water core T 2 Spectrum P w The method comprises the steps of carrying out a first treatment on the surface of the Drying the core to constant weight and then saturating n-decane to determine a saturated oil core T 2 Spectrum P o The method comprises the steps of carrying out a first treatment on the surface of the Self-sucking distilled water from core of saturated oil, and measuring core magnetism T after self-sucking balance 2 Spectrum P ow The method comprises the steps of carrying out a first treatment on the surface of the Re-saturating n-decane to the core, self-sucking heavy water, and measuring core magnetism T 2 Spectrum P or The method comprises the steps of carrying out a first treatment on the surface of the Drying and performing high-pressure mercury-pressing test; and calculating to obtain the full-pore-size distribution of the core based on experimental data. According to the method, the full-pore-size distribution characterization of the shale core is realized by measuring the fluid distribution of the shale core in self-water absorption balance after the shale core is pressurized with saturated oil.
Description
Technical Field
The invention relates to a reservoir core pore structure research in petroleum engineeringThe field is specifically related to a nuclear magnetism T-based 2 A method for measuring the full-pore-size distribution of a shale oil reservoir core of a spectrum.
Background
Shale oil reservoirs develop both micro-scale cracks and are rich in nano-scale pores, having a multi-scale pore structure. The conventional low-temperature gas adsorption method and field emission scanning electron microscopy method are difficult to characterize the full-scale pore size distribution of the shale oil reservoir due to the limitation of the measurement range. High pressure mercury porosimetry requires destruction of the rock sample, high pressure is prone to change the primary pore structure and no reservoir space between clay layers is detectable where oil and water can enter. The rock pore diameter distribution determination method based on the low-field nuclear magnetic resonance technology has the advantages of no damage to rock samples, wide test range and the like, and is one of widely applied shale pore structure characterization methods.
The prior research is mainly carried out on T under the condition of shale single saturated oil or water 2 The spectrum characterizes the shale pore size distribution. Shale oil reservoirs, however, have a large number of nanoscale pores and have complex heterogeneous mixed wettability characteristics. Because the pore diameter is too small and the nano-scale pores of the capillary force acting part cannot be driven to saturate non-wetting fluid by pressure, single saturated oil or water can cause partial water-wet nano-pores or oil-wet nano-pores in shale to be not saturated, and the T is tested in the state 2 The spectrum also fails to characterize the unsaturated nanopores, making it difficult to achieve shale full pore size distribution characterization. To sum up, the existing nuclear magnetism T-based 2 The shale oil reservoir core pore size distribution determination method of the spectrum is still to be improved.
Disclosure of Invention
The invention aims at being based on nuclear magnetism T 2 Method for measuring full pore diameter distribution of shale oil reservoir core based on spectrum, and method based on nuclear magnetism T 2 The method for determining the full-aperture distribution of the shale oil reservoir core of the spectrum is used for solving the problem of nuclear magnetism-based T in the prior art 2 According to the method for measuring the pore size distribution of the shale oil reservoir core of the spectrum, the characteristics of non-uniform mixing wettability of the shale oil reservoir core are not considered, the shale oil reservoir core is rich in nano pores, and the problem that the full pore size distribution characterization of the core cannot be realized because the core is difficult to saturate completely by adopting a single liquid (oil or water) saturated core.
The technical scheme adopted for solving the technical problems is as follows: such a magnetic core-based T 2 The method for measuring the full-pore-size distribution of the shale oil reservoir core of the spectrum comprises the following steps:
step (1), drying the core at 110 ℃ to constant weight, and carrying out nuclear magnetism T 2 Spectrum test to determine core dry sample T 2 Spectrum P in ；
Step (2), carrying out nuclear magnetism T on the coring core in a saturated distilled water state by using the saturated distilled water of the coring core 2 Spectrum test to determine saturated water core T 2 Spectrum P w ；
Step (3), drying the coring core to constant weight at 110 ℃, saturating the coring core with n-decane, and performing nuclear magnetism T on the coring core in the saturated n-decane state 2 Spectrum test to determine saturated oil core T 2 Spectrum P o ；
Step (4), enabling the core of the saturated oil to self-absorb distilled water, and measuring core nuclear magnetism T after self-absorption balance 2 Spectrum P ow ；
Step (5), drying the coring core to constant weight at 110 ℃, re-saturating the coring core with n-decane, then self-sucking heavy water, and measuring the core nuclear magnetism T after self-sucking balance 2 Spectrum P or ；
Step (6), taking a core parallel sample, drying the core parallel sample to constant weight at 110 ℃, and carrying out high-pressure mercury-pressing test on the core parallel sample;
and (7) calculating to obtain the full-pore-size distribution of the core based on experimental data.
The specific calculation method of the step (7) in the scheme comprises the following steps:
(1) will P w Subtracting P in Selecting the obtained T 2 T in spectrum 2 The part of the core which is more than or equal to 0.2ms obtains the nuclear magnetism T corresponding to the saturated water distribution in the core 2 Spectrum P wi The method comprises the steps of carrying out a first treatment on the surface of the Will P o Subtracting P in Selecting the obtained T 2 T in spectrum 2 The part of the core is more than or equal to 0.2ms to obtain the nuclear magnetism T corresponding to the distribution of saturated oil in the core 2 Spectrum P oi The method comprises the steps of carrying out a first treatment on the surface of the Will P or Subtracting P in Selecting the obtained T 2 T in spectrum 2 ≥0.2mThe part s obtains the nuclear magnetism T corresponding to the distribution of the residual oil after the saturated oil core absorbs water 2 Spectrum P ori ；
(2) According to P wi 、P oi Determination of the transverse relaxation time T of water from the results of the high-pressure mercury-pressing test 2w Conversion relation R with core pore throat radius R w Transverse relaxation time T of oil 2o Conversion relation R with core pore throat radius R o ；
(3) According to R o P ori Obtaining the pore distribution B of the residual oil of the saturated oil core after self-water absorption or ；
(4) From P ow Subtracting P in turn in 、P ori T obtained 2 T in spectrum 2 The part more than or equal to 0.2ms obtains the nuclear magnetism T 2 Spectrum P w1 According to R w P w1 Obtaining pore distribution B of water after self-absorption of saturated oil core w ；
(5) Will B w And B is connected with or Accumulating to obtain shale full-pore-size distribution B;
(6) comparing B with the test result of high-pressure mercury, if not, then B and R w Obtaining the core magnetic T corresponding to water distribution when the core is fully porous and saturated 2 Spectrum P wif From B and R o Oil is distributed to correspond to nuclear magnetism T when saturated oil with all holes of core is obtained 2 Spectrum P oif Will P wif P oif Respectively comparing with the test results of high-pressure mercury pressing, respectively determining T 2w Conversion relation R with R wf T and T 2o Conversion relation R with R of R is taken as wf And R is of Respectively replace R w And R is o Repeating steps (3) - (5);
(7) and (3) repeating the step (6) until the B is matched with the high-pressure mercury injection test result, and taking the B as shale full-pore-size distribution after calculation.
The specific method of the step (4) in the scheme is as follows: placing the core after saturated oil in a static pressurization visualization imbibition experimental device, injecting distilled water into the imbibition experimental device to enable the core to be completely immersed in the distilled water, and observing imbibition of the extracted oil every 24 hours through a visualization windowTaking out the coring core every 24 hours after the volume of the imbibition produced oil is constant, weighing after removing redundant liquid on the coring core according to the standard GB/T29172-2012 core analysis method, and performing nuclear magnetism T on the coring core according to the standard SY/T6490-2014 rock sample nuclear magnetic resonance parameter laboratory measurement standard when the coring core is balanced by self-priming when the coring core is constant in mass 2 Spectrum test, core T for determining self-priming water balance state after saturated oil 2 Spectrum P ow 。
The specific method of the step (5) in the scheme is as follows: drying the coring core to constant weight at 110 ℃, saturating the coring core with n-decane again according to the standard GB/T29172-2012 core analysis method, placing the coring core after saturated oil in a static pressurization visualization imbibition experimental device, injecting heavy water into the imbibition experimental device to enable the coring core to be completely immersed in the heavy water, observing the volume of imbibition produced oil every 24 hours through a visualization window, taking out the coring core every 24 hours after the volume of imbibition produced oil is constant, weighing the coring core after removing redundant liquid on the coring core according to the standard GB/T29172-2012 core analysis method, considering the coring core to be self-absorption balanced when the coring core quality is constant, and performing nuclear magnetic T on the coring core according to the standard SY/T6490-2014 rock sample nuclear magnetic resonance parameter laboratory measurement standard 2 Spectrum test to determine core T of self-priming heavy water balance state after saturated oil 2 Spectrum P or 。
Further, the specific calculation method of the step (7) in the above scheme is as follows:
(1) will P w Subtracting P in Selecting the obtained T 2 T in spectrum 2 The part of the core which is more than or equal to 0.2ms obtains the nuclear magnetism T corresponding to the saturated water distribution in the core 2 Spectrum P wi The method comprises the steps of carrying out a first treatment on the surface of the Will P o Subtracting P in Selecting the obtained T 2 T in spectrum 2 The part of the core is more than or equal to 0.2ms to obtain the nuclear magnetism T corresponding to the distribution of saturated oil in the core 2 Spectrum P oi The method comprises the steps of carrying out a first treatment on the surface of the Will P or Subtracting P in Selecting the obtained T 2 T in spectrum 2 The part of the magnetic flux is more than or equal to 0.2ms to obtain the nuclear magnetism T corresponding to the distribution of the residual oil after the self-absorption of the saturated oil core 2 Spectrum P ori ；
(2) According to P wi 、P oi Determination of T from high-pressure mercury-pressing test results 2w Conversion relation R with R w T and T 2o Conversion relation R with R o : conversion relation typeT 2 =C f r n f (1) In the formula (1)C f 、n f For constants related to core properties, pore structure and fluid properties, compare P wi Finding out T corresponding to peak value in two distributions respectively according to pore throat distribution obtained by high-pressure mercury-pressing test 2 The value and the r value determine the corresponding T of the array 2 -r, converting formula (1) into log T 2 = log C f +n f log rLog r is taken as an independent variable, log T 2 Determining optimal parameters for dependent variables using least squaresC f 、n f To determine T 2w The conversion relation of r, and likewise T 2o -a conversion relation of r;
(3) according to R o Will P ori Middle T 2 Converted into r to obtain the pore distribution B of the residual oil of the saturated oil core after self-water absorption or ；
(4) From P ow Subtracting P in turn in 、P ori T obtained 2 T in spectrum 2 The part more than or equal to 0.2ms obtains the nuclear magnetism T 2 Spectrum P w1 According to R w Will P w1 Middle T 2 Converted into r to obtain the pore distribution B of water after the saturated oil core absorbs water w ；
(5) Will B w And B is connected with or Accumulating to obtain shale full-pore-size distribution B;
(6) comparing B with pore-throat distribution obtained by high-pressure mercury test, respectively finding out r values corresponding to peak values in the two distributions, determining an array of r values corresponding to each other, if the r value of the adjacent measuring point on the left side of the measuring point corresponding to the peak value on the high-pressure mercury pore-throat distribution curve is not more than 6nm, discarding the r values corresponding to each other, and obtaining the r in the pore-throat distribution obtained by the high-pressure mercury testCalculating the average relative error e of the r value in the B by taking the r value in the B as a predicted value, and if e is less than or equal to 0.05, matching the B with the pore-throat distribution obtained by the high-pressure mercury-pressing test, otherwise, not matching; if B is not matched with the pore-throat distribution obtained by the high-pressure mercury-pressing test, according to R w Converting r value in B into T 2 Obtaining the nuclear magnetism T corresponding to water distribution when the core is fully porous and saturated 2 Spectrum P wif According to R o Converting r value in B to T 2 Obtaining the corresponding nuclear magnetism T of oil distribution when the saturated oil of all pores of the core 2 Spectrum P oif According to P wif 、P oif And the test result of high-pressure mercury pressing, respectively determining T 2w Conversion relation R with R wf T and T 2o Conversion relation R with R of R is taken as wf And R is of Respectively replace R w And R is o Repeating steps (3) - (5);
(7) and (3) repeating the step (6) until the good calculation of the coincidence of the B and the high-pressure mercury injection test result is finished, and taking the B as the shale full-pore-size distribution.
Advantageous effects
1. According to the invention, the self-water-absorption fluid after the shale core is pressurized with saturated oil can occupy all pores including water-wet nano pores, oil-wet nano pores and pores which can be saturated by pressure driving in the core, and the heavy water is similar to the water in physical property and has no nuclear magnetic signal, and the saturated oil core has nuclear magnetic T after self-absorption of heavy water 2 The spectrum can reflect the distribution of the residual oil after the saturated oil core absorbs water by itself and combine the nuclear magnetism T of the saturated oil core after absorbing water by itself 2 The oil-water distribution in the total fluid distribution reflected by the spectrum can be further distinguished, and the invention establishes a nuclear magnetism T-based 2 According to the method, the characteristic that the shale oil reservoir nano pores have complex non-uniform mixing wettability is considered, and the full-pore-size distribution characterization of the shale core is realized by measuring the fluid distribution of the shale core when self-water absorption is balanced after the shale core is pressurized with saturated oil.
2. The invention is harmless to rock sample, can characterize multi-scale pore structure and can make up for the existing nuclear magnetism-based T 2 Shale core pore size distribution determination method of spectrum adopts single fluid saturated rockThe heart results in the disadvantage that some of the non-wetted nanopores of the fluid cannot be saturated and are therefore difficult to characterize.
Drawings
FIG. 1 is T 2 The spectrum versus pore throat distribution for high pressure mercury tests is shown schematically as T 2a -r a 、T 2b -r b 、T 2c -r c 、T 2d -r d 、T 2e -r e Respectively correspond to each other.
Fig. 2 is a schematic diagram of a comparison method of the full pore diameter distribution of the shale core and the pore-throat distribution of the high-pressure mercury test, wherein a is the full pore diameter distribution of the shale core, b is the pore-throat distribution of the high-pressure mercury test of the shale core, and r is shown in the figure y1 -r 1 、r y2 -r 2 、r y3 -r 3 、r y4 -r 4 、r y5 -r 5 Respectively correspond to each other.
Detailed Description
The invention is further described below with reference to the accompanying drawings:
such a magnetic core-based T 2 The method for measuring the full-pore-size distribution of the shale oil reservoir core of the spectrum comprises the following steps.
(1) Drying the core at 110deg.C to constant weight, and developing nuclear magnetism T for the dried core with reference to standard SY/T6490-2014 rock sample nuclear magnetic resonance parameter laboratory measurement Specification 2 Spectrum test to determine core dry sample T 2 Spectrum P in ；
(2) Vacuumizing the core and saturating distilled water according to the reference standard GB/T29172-2012 core analysis method, and performing nuclear magnetism T on the core in the saturated water state according to the reference standard SY/T6490-2014 rock sample nuclear magnetic resonance parameter laboratory measurement Specification 2 Spectrum test to determine saturated water core T 2 Spectrum P w ；
(3) Drying the core at 110deg.C to constant weight, saturating n-decane with core by reference to standard GB/T29172-2012 core analysis method, and performing nuclear magnetism T on core in saturated oil state by reference to standard SY/T6490-2014 nuclear magnetic resonance parameter laboratory measurement specification 2 Spectrum test to determine saturated oil core T 2 Spectrum P o ；
(4) Placing the saturated oil core in a static pressurization visual imbibition experimental device, injecting distilled water into the imbibition experimental device to enable the core to be completely immersed in the distilled water, observing the volume of imbibition produced oil every 24 hours through a visual window, taking out the core every 24 hours after the volume of imbibition produced oil is constant, weighing after removing redundant liquid on the core according to the standard 'GB/T29172-2012 core analysis method', considering self-absorption balance of the core when the core quality is constant, and carrying out nuclear magnetism T on the core according to the standard 'SY/T6490-2014 rock sample nuclear magnetic resonance parameter laboratory measurement standard' 2 Spectrum test, core T for determining self-priming water balance state after saturated oil 2 Spectrum P ow ；
(5) Drying the core to constant weight at 110 ℃, referring to a standard GB/T29172-2012 core analysis method, saturating the core with n-decane again, placing the saturated oil core in a static pressurization visualization imbibition experimental device, injecting heavy water into the imbibition experimental device to enable the core to be completely immersed in the heavy water, observing the volume of imbibition produced oil every 24 hours through a visualization window, taking out the core every 24 hours after the volume of imbibition produced oil is constant, weighing the core after removing redundant liquid on the core according to the standard GB/T29172-2012 core analysis method, considering the core to be self-suction balanced when the core quality is constant, and referring to a standard SY/T6490-2014 rock sample nuclear magnetic resonance parameter laboratory measurement standard, and performing nuclear magnetism T on the core 2 Spectrum test to determine core T of self-priming heavy water balance state after saturated oil 2 Spectrum P or ；
(6) The core parallel sample is dried to constant weight at 110 ℃, and the pore size distribution and the porosity of the solid material are measured according to the standard GB/T21650.1 2008 mercury porosimetry and a gas adsorption method, part 1: carrying out high-pressure mercury-pressing test on the rock core by mercury-pressing method to determine pore-throat distribution of the rock core;
(7) The core full-pore-size distribution is obtained based on experimental data by calculation, and the specific calculation method comprises the following steps:
(1) will P w Subtracting P in Selecting the obtained T 2 T in spectrum 2 Part of 0.2ms or moreObtaining the nuclear magnetism T corresponding to the distribution of saturated water in the core 2 Spectrum P wi The method comprises the steps of carrying out a first treatment on the surface of the Will P o Subtracting P in Selecting the obtained T 2 T in spectrum 2 The part of the core is more than or equal to 0.2ms to obtain the nuclear magnetism T corresponding to the distribution of saturated oil in the core 2 Spectrum P oi The method comprises the steps of carrying out a first treatment on the surface of the Will P or Subtracting P in Selecting the obtained T 2 T in spectrum 2 The part of the magnetic flux is more than or equal to 0.2ms to obtain the nuclear magnetism T corresponding to the distribution of the residual oil after the self-absorption of the saturated oil core 2 Spectrum P ori ；
(2) According to P wi 、P oi Determination of T from high-pressure mercury-pressing test results 2w Conversion relation R with R w T and T 2o Conversion relation R with R o : the conversion relation can be selected fromT 2 =C f r n f (1) In the followingC f 、n f For constants related to core properties, pore structure, and fluid properties, P can be compared wi Finding out T corresponding to peak value in two distributions respectively according to pore throat distribution obtained by high-pressure mercury-pressing test 2 The value and r value (see figure 1) to determine the corresponding T of the array 2 -r, converting formula (1) into log T 2 = log C f +n f log rLog r is taken as an independent variable, log T 2 Determining optimal parameters for dependent variables using least squaresC f 、n f Can determine T 2w The conversion relation of r and, in the same way, T can also be determined 2o -a conversion relation of r;
(3) according to R o Will P ori Middle T 2 Converted into r to obtain the pore distribution B of the residual oil of the saturated oil core after self-water absorption or ；
(4) From P ow Subtracting P in turn in 、P ori T obtained 2 T in spectrum 2 The part more than or equal to 0.2ms obtains the nuclear magnetism T 2 Spectrum P w1 According to R w Will P w1 Middle T 2 Converted into r to obtain the pore distribution of water after the saturated oil core absorbs waterB w ；
(5) Will B w And B is connected with or Accumulating to obtain shale full-pore-size distribution B;
(6) comparing B with pore-throat distribution obtained by high-pressure mercury test, respectively finding out r values corresponding to peak values in the two distributions (see figure 2), further determining an array of r values corresponding to each other, considering that the high-pressure mercury test cannot detect the storage space between clay layers which can be entered by oil and water, if the r value of the left adjacent measuring point of the measuring point corresponding to the peak value obtained on the high-pressure mercury pore-throat distribution curve is not more than 6nm, discarding the r values corresponding to each pair of the array, taking the r value in the pore-throat distribution obtained by the high-pressure mercury test as an actual value, taking the r value in the B as a predicted value, calculating the average relative error e of the r value in the B, and if e is less than or equal to 0.05, considering that the B is well matched with the pore-throat distribution obtained by the high-pressure mercury test, otherwise, and if not, carrying out the matching. If B is not matched with the pore-throat distribution obtained by the high-pressure mercury-pressing test, the method is based on R w Converting r value in B to T 2 Obtaining the nuclear magnetism T corresponding to water distribution when the core is fully porous and saturated 2 Spectrum P wif According to R o Converting r value in B to T 2 Obtaining the corresponding nuclear magnetism T of oil distribution when the saturated oil of all pores of the core 2 Spectrum P oif According to P wif 、P oif And determining T respectively with reference to the method set forth in step (2) for the high-pressure mercury-pressing test results 2w Conversion relation R with R wf T and T 2o Conversion relation R with R of R is taken as wf And R is of Respectively replace R w And R is o Repeating steps (3) - (5);
(7) and (3) repeating the step (6) until the good calculation of the coincidence of the B and the high-pressure mercury injection test result is finished, and taking the B as the shale full-pore-size distribution.
In FIG. 2, r y1 -r 1 、r y2 -r 2 、r y3 -r 3 、r y4 -r 4 、r y5 -r 5 Respectively corresponding to the left adjacent measuring point r value of the measuring point corresponding to the first peak value in the high-pressure mercury test pore throat distribution diagram is not more than 6nm, and the average relative error between the shale core full-pore diameter distribution and the high-pressure mercury test result is calculated without considerationr y0 -r 0 。
The static pressurization visual imbibition experimental device adopts a Chinese patent application ZL202010525235.8, is a static pressurization visual imbibition experimental device for a tight reservoir rock core, and comprises an upper pressurization device, a lower pressurization device, imbibition bottles, a camera device and a constant temperature box, wherein the upper pressurization device is connected with an inlet pipe at the upper end of the imbibition bottles, the lower pressurization device is connected with an inlet at the lower end of the imbibition bottles, the camera device is arranged at an imbibition visual window of the imbibition bottles, and the imbibition bottles are arranged in the constant temperature box; the seepage bottle is formed by integrally connecting a visual metering tube, a conical connecting device and a sample chamber from top to bottom, wherein the sample chamber is provided with a seepage visual window, the lower end of the sample chamber is provided with a detachable lower end cover, the upper end of the sample chamber is in threaded connection with the conical connecting device, the conical connecting device is provided with a conical cavity, the upper port of the conical cavity is connected with an upper end inlet tube, the lower port of the conical cavity is connected with the inner cavity of the sample chamber, the visual metering tube is fixed on the conical connecting device, and the upper end inlet tube is arranged in the visual metering tube; the upper pressurizing device and the lower pressurizing device both comprise an ISCO pump and an intermediate container, the intermediate container is provided with an inlet valve and an outlet valve, the outlet valve is connected with an inlet pipe at the upper end of the imbibition bottle, and a pressure gauge is arranged on a pipeline between the outlet valve and the inlet pipe at the upper end of the imbibition bottle.
The upper end cover is provided with a central hole, an inlet pipe at the upper end of the imbibition bottle is connected with the central hole, and the inlet pipe at the upper end of the imbibition bottle is connected with the upper pressurizing device through the central hole; the upper end cover is bottle cap-shaped and consists of an upper groove and an outer edge groove wall; the tapered connection means has a lower groove and an outer rim groove wall.
The two ends of the visual metering tube are provided with elastic rubber gaskets, the upper port of the visual metering tube is positioned in the upper groove of the upper end cover, the upper port of the visual metering tube is positioned in the lower groove of the conical connecting device, the elastic rubber gaskets are integrally formed by a horizontal part and a vertical part, the vertical part of the elastic rubber gaskets at the upper end is sleeved outside the upper port of the visual metering tube, the vertical part is positioned in an annular space between the outer edge groove wall of the upper end cover and the upper port of the visual metering tube, and the horizontal part is positioned between the upper end cover and the supporting stud; the vertical part of the elastic rubber pad at the lower end is sleeved outside the lower port of the visual metering tube, and is positioned in an annular space between the outer edge groove wall of the conical connecting device and the lower port of the visual metering tube, and the horizontal part is positioned between the conical connecting device and the supporting stud.
The sample chamber is provided with a round windowsill, the round windowsill is perpendicular to the sample chamber and welded into a whole, the seepage visual window is fastened on the round windowsill through a window frame at the outer edge of the round windowsill through bolts, and the thickness of the seepage visual window is equal to that of the window frame at the outer edge of the seepage visual window; the seepage visual window and the round windowsill form a detachable cavity, and the change of the whole static seepage oil extraction process can be visually observed through the sealed visual window of the seepage bottle, and the extracted tiny oil quantity can be stored.
The visual metering tube is fixed between the upper end cover and the conical connecting device through four support studs, the four support studs are uniformly distributed around the visual metering tube, one end of each support stud is fastened with the upper end cover, the other end of each support stud is fixed with the conical connecting device and abuts against the wall of the sample chamber, and the visual metering tube is centrally fixed between the upper groove of the upper end cover and the lower groove of the conical connecting device; and a cushion block is sleeved in the middle of each support stud, the cushion block is fastened on the support stud through nuts on the upper part and the lower part of the cushion block, and one end of the cushion block is tangent to the visual metering tube.
The two seepage visual windows are symmetrically arranged relative to the sample chamber, the camera device is composed of a double-lens high-definition camera and a computer terminal, the double-lens high-definition camera is arranged at the seepage visual window, and the double-lens high-definition camera is connected with the computer terminal.
Claims (3)
1. Based on nuclear magnetism T 2 The method for measuring the full-pore-size distribution of the shale oil reservoir core of the spectrum is characterized by comprising the following steps of:
step (1), drying the core at 110 ℃ to constant weight, and carrying out nuclear magnetism T 2 Spectrum test to determine core dry sample T 2 Spectrum P in ；
Step (2), carrying out nuclear magnetism T on the coring core in a saturated distilled water state by using the saturated distilled water of the coring core 2 Spectrum test to determine saturated water core T 2 Spectrum P w ；
Step (3), drying the coring core to constant weight at 110 ℃, saturating the coring core with n-decane, and performing nuclear magnetism T on the coring core in the saturated n-decane state 2 Spectrum test to determine saturated oil core T 2 Spectrum P o ；
Step (4), enabling the core of the saturated oil to self-absorb distilled water, and measuring core nuclear magnetism T after self-absorption balance 2 Spectrum P ow ；
Step (5), drying the coring core to constant weight at 110 ℃, re-saturating the coring core with n-decane, then self-sucking heavy water, and measuring the core nuclear magnetism T after self-sucking balance 2 Spectrum P or ；
Step (6), taking a core parallel sample, drying the core parallel sample to constant weight at 110 ℃, and carrying out high-pressure mercury-pressing test on the core parallel sample;
step (7), calculating to obtain the full pore size distribution of the core based on experimental data;
(1) will P w Subtracting P in Selecting the obtained T 2 T in spectrum 2 The part of the core which is more than or equal to 0.2ms obtains the nuclear magnetism T corresponding to the saturated water distribution in the core 2 Spectrum P wi The method comprises the steps of carrying out a first treatment on the surface of the Will P o Subtracting P in Selecting the obtained T 2 T in spectrum 2 The part of the core is more than or equal to 0.2ms to obtain the nuclear magnetism T corresponding to the distribution of saturated oil in the core 2 Spectrum P oi The method comprises the steps of carrying out a first treatment on the surface of the Will P or Subtracting P in Selecting the obtained T 2 T in spectrum 2 The part of the magnetic flux is more than or equal to 0.2ms to obtain the nuclear magnetism T corresponding to the distribution of the residual oil after the self-absorption of the saturated oil core 2 Spectrum P ori ；
(2) According to P wi 、P oi Determination of T from high-pressure mercury-pressing test results 2w Conversion relation R with R w T and T 2o Conversion relation R with R o : conversion relation T 2 ＝C f r nf (1) C in formula (1) f 、n f For constants related to core properties, pore structure and fluid properties, compare P wi Finding out T corresponding to peak value in two distributions respectively according to pore throat distribution obtained by high-pressure mercury-pressing test 2 The value and the r value determine the corresponding T of the array 2 -r, converting formula (1) into log T 2 ＝log C f +n f log r, log T with log r as an independent variable 2 Determining optimal parameter C for dependent variable by least square method f 、n f To determine T 2w The conversion relation of r, and likewise T 2o -a conversion relation of r;
(3) according to R o Will P ori Middle T 2 Converted into r to obtain the pore distribution B of the residual oil of the saturated oil core after self-water absorption or ；
(4) From P ow Subtracting P in turn in 、P ori T obtained 2 T in spectrum 2 The part more than or equal to 0.2ms obtains the nuclear magnetism T 2 Spectrum P w1 According to R w Will P w1 Middle T 2 Converted into r to obtain the pore distribution B of water after the saturated oil core absorbs water w ；
(5) Will B w And B is connected with or Accumulating to obtain shale full-pore-size distribution B;
(6) comparing B with pore-throat distribution obtained by a high-pressure mercury test, respectively finding out r values corresponding to peak values in the two distributions, determining an array of r values corresponding to each other, if the r value of the adjacent measuring point on the left side of the measuring point corresponding to the peak value on the high-pressure mercury pore-throat distribution curve is not more than 6nm, discarding the r values corresponding to each group, taking the r value in the pore-throat distribution obtained by the high-pressure mercury test as an actual value, taking the r value in the B as a predicted value, calculating the average relative error e of the r value in the B, and if e is less than or equal to 0.05, matching the B with the pore-throat distribution obtained by the high-pressure mercury test, otherwise, not matching; if B is not matched with the pore-throat distribution obtained by the high-pressure mercury-pressing test, according to R w Converting r value in B into T 2 Obtaining the nuclear magnetism T corresponding to water distribution when the core is fully porous and saturated 2 Spectrum P wif According to R o Converting r value in B to T 2 Obtaining the corresponding nuclear magnetism T of oil distribution when the saturated oil of all pores of the core 2 Spectrum P oif According to P wif 、P oif And the test result of high-pressure mercury pressing, respectively determining T 2w Conversion relation R with R wf T and T 2o Conversion relation R with R of R is taken as wf And R is of Respectively replaceR is replaced w And R is o Repeating steps (3) - (5);
(7) and (3) repeating the step (6) until the good calculation of the coincidence of the B and the high-pressure mercury injection test result is finished, and taking the B as the shale full-pore-size distribution.
2. The nuclear magnetic T-based magnetic resonance system of claim 1 2 The method for measuring the full-pore-size distribution of the shale oil reservoir core of the spectrum is characterized by comprising the following steps of: the specific method of the step (4) is as follows: placing the coring core after saturated oil in a static pressurization visualization imbibition experimental device, injecting distilled water into the imbibition experimental device to enable the coring core to be completely immersed in the distilled water, observing the volume of imbibition produced oil every 24 hours through a visualization window, taking out the coring core every 24 hours after the volume of imbibition produced oil is constant, weighing after removing redundant liquid on the coring core according to the standard GB/T29172-2012 core analysis method, carrying out core self-absorption balance when the coring core is constant in quality, and carrying out nuclear magnetic T on the coring core according to the standard SY/T6490-2014 rock sample nuclear magnetic resonance parameter laboratory measurement standard 2 Spectrum test, core T for determining self-priming water balance state after saturated oil 2 Spectrum P ow 。
3. Nuclear magnetic T-based according to claim 2 2 The method for measuring the full-pore-size distribution of the shale oil reservoir core of the spectrum is characterized by comprising the following steps of: the specific method of the step (5) is as follows: drying the coring core to constant weight at 110 ℃, saturating the coring core with n-decane again according to the standard GB/T29172-2012 core analysis method, placing the coring core after saturated oil in a static pressurization visualization imbibition experimental device, injecting heavy water into the imbibition experimental device to enable the coring core to be completely immersed in the heavy water, observing the volume of imbibition produced oil every 24 hours through a visualization window, taking out the coring core every 24 hours after the volume of imbibition produced oil is constant, weighing the coring core after removing redundant liquid on the coring core according to the standard GB/T29172-2012 core analysis method, considering the coring core to be self-suction balanced when the coring core quality is constant, and taking the coring core according to the standard SY/T6490-2014 rock sample nuclear magnetic resonance parameter laboratory measurement standardCore nuclear magnetism T 2 Spectrum test to determine core T of self-priming heavy water balance state after saturated oil 2 Spectrum P or 。
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