CN113720869B - Nuclear magnetic resonance T for invasion of oil-based mud into low-porosity water layer 2 Geometric mean value correction method and system - Google Patents
Nuclear magnetic resonance T for invasion of oil-based mud into low-porosity water layer 2 Geometric mean value correction method and system Download PDFInfo
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- 238000005481 NMR spectroscopy Methods 0.000 title claims abstract description 670
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Abstract
The invention provides a nuclear magnetic resonance T for invasion of oil-based mud into low-porosity water layer 2 Geometric mean value correction method and systemAnd (4) a system. The method comprises the following steps: obtaining nuclear magnetic resonance T of target oil-bearing mud invading low-porosity water layer 2 Nuclear magnetic resonance T of geometric mean, invasion oil-based mud 2 A geometric mean value; obtaining nuclear magnetic resonance T of formation 2 Geometric mean nuclear magnetic resonance T after invasion of oil-based mud by formation 2 Nuclear magnetic resonance T of oil-based mud with geometric mean and formation invasion 2 A calculation model of the geometric mean; nuclear magnetic resonance T based on invasion of target oil-bearing-based mud into low-porosity water layer 2 Nuclear magnetic resonance T of geometric mean, invasion oil-based mud 2 Geometric mean value, and determining the nuclear magnetic resonance T of the 100% water-saturated state of the stratum with the target oil-based mud invading the low-porosity water layer by using the calculation model 2 Geometric mean value, thereby completing the nuclear magnetic resonance T of the target oil-bearing mud invading the low-porosity water layer 2 And correcting the geometric mean value.
Description
Technical Field
The invention belongs to the field of reservoir stratum evaluation, and particularly relates to a nuclear magnetic resonance T for oil-based mud invading low-porosity water layer 2 A geometric mean correction method and system.
Background
T 2 Geometric meanIs a very important parameter in the nuclear magnetic resonance well logging data interpretation, and the numerical value of the parameter reflects the rock nuclear magnetic resonance T qualitatively and visually 2 The width of the spectrum and the relative position of the main peaks. By using the method, the pore structure of the rock can be qualitatively reflected and the permeability of the rock can be quantitatively calculated. In general, for a unimodal distribution of nuclear magnetic resonance T 2 Spectrum, T thereof 2 Geometric mean and nuclear magnetic resonance T 2 T corresponding to position of main peak of spectrum 2 Relaxation time coincidence, while for NMR T of non-unimodal distribution 2 Spectrum, T 2 The wider the distribution, the more to the right the position of the main peak, the corresponding T 2 The larger the geometric mean value is, the rock is reflected to be mainly distributed by macropores, and the better the pore structure is; otherwise, T 2 The narrower the distribution, the more left the position of the main peak, the corresponding T 2 The smaller the geometric mean value is, the more the rock is mainly distributed by small pores, and the worse the pore structure is. Thus, T 2 The size of the geometric mean value can visually and qualitatively reflect the pore structure of the rock. In general, use is made of the measured nuclear magnetic resonance T 2 Spectrum, can directly calculate T of rock 2 Geometric mean. On the basis of the above-mentioned formula, it is established that the nuclear magnetic resonance T is used 2 The geometric mean value is used for calculating permeability and constructing a pseudo capillary pressure curve so as to quantitatively represent the rock pore structure. However, the above methods and models are based on nmr experiments in which the core is 100% water-saturated. When rock, especially low porosity rock, is affected by the invasion of oil-based mud, the emulsifiers carried by the oil-based mud invade the rock pore space. Influenced by the NMR relaxation properties of the emulsifier, resulting in a measured NMR T 2 Morphology of spectra and corresponding nuclear magnetic resonance T 2 The geometric mean values all change. At this time, if the measured NMR well log T is directly used 2 Spectral calculated T 2 The geometric mean value is used for evaluating the permeability and the pore structure of the reservoir, and an error evaluation result is obtained. In the water layer invaded by oil-based mud, in order to utilize nuclear magnetic resonance T 2 Geometric means accurately evaluate reservoir permeability and pore structure, which needs to be corrected to a 100% saturated water state. However, at present, there is no method for nuclear magnetic resonanceT 2 The methods for correcting geometric mean values are reported in the literature.
Disclosure of Invention
In view of the shortcomings of the prior art, the invention aims to provide a nuclear magnetic resonance T capable of effectively correcting invasion of oil-based mud into a low-porosity water layer 2 The method of the geometric mean value effectively solves the problem that the low-porosity water layer is influenced by invasion of the oil-based mud, and the nuclear magnetic resonance T is obtained based on the nuclear magnetic resonance well logging 2 The geometric mean value cannot reflect the problem of the real condition of the stratum.
In order to achieve the aim, the invention provides a nuclear magnetic resonance T of oil-based mud invading low-porosity water layer 2 A geometric mean correction method, wherein the method comprises:
obtaining nuclear magnetic resonance T of target oil-bearing mud invading low-porosity water layer 2 A geometric mean value;
obtaining nuclear magnetic resonance T of invasion oil-based mud in low-porosity water layer invaded by target oil-based mud 2 A geometric mean value;
obtaining nuclear magnetic resonance T of formation 2 Geometric mean nuclear magnetic resonance T after invasion of oil-based mud by formation 2 Nuclear magnetic resonance T of oil-based mud with geometric mean and formation invasion 2 A calculation model of the geometric mean;
nuclear magnetic resonance T based on invasion of target oil-bearing mud into low-porosity water layer 2 Nuclear magnetic resonance T of oil-based mud invasion into low-porosity water layer by geometric mean and target oil-based mud invasion 2 Geometric mean, using nuclear magnetic resonance T of the formation 2 Geometric mean nuclear magnetic resonance T after invasion of oil-based mud by formation 2 Nuclear magnetic resonance T of geometric mean and invaded oil-based mud 2 A calculation model of a geometric mean value is used for determining the nuclear magnetic resonance T of a 100% water-saturated state of a stratum with a target invaded by oil-based mud into a low-porosity water layer 2 Geometric mean value, thereby completing the nuclear magnetic resonance T of the target oil-bearing mud invading the low-porosity water layer 2 And correcting the geometric mean value.
NMR T of said oil-based mud into low porosity water layer 2 In the geometric mean correction method, excellenceOptionally, the low porosity is a porosity of no more than 15%.
NMR T of said oil-based mud into low porosity water layer 2 In the geometric mean correction method, preferably, the nuclear magnetic resonance T of the target oil-bearing mud invading the low-porosity water layer is obtained 2 The geometric mean includes:
nuclear magnetic resonance logging T for acquiring invasion of target oil-bearing mud into low-porosity water layer 2 A spectrum;
nuclear magnetic resonance logging T based on invasion of target oil-bearing mud into low-porosity water layer 2 Spectrum, nuclear magnetic resonance T for determining invasion of target oil-bearing mud into low-porosity water layer 2 Geometric mean.
NMR T of said oil-based mud into low porosity water layer 2 In the geometric mean correction method, preferably, the nuclear magnetic resonance T of the invasion oil-based mud of the target oil-based mud invaded into the low-porosity water layer is obtained 2 The geometric mean includes:
obtaining nuclear magnetic resonance T of invasion oil-based mud in low-porosity water layer invaded by target oil-based mud 2 A spectrum;
nuclear magnetic resonance T based on invasion of target oil-bearing mud into low-porosity water layer 2 Spectroscopy, determining the NMR T of the target oil-based mud invaded into the low porosity water layer 2 A geometric mean value;
in one embodiment, nuclear magnetic resonance T of invasion of oil-based mud into a low porosity water layer from a target oil-based mud is obtained 2 The spectra include:
performing nuclear magnetic resonance test on the oil-based mud invaded into the low-porosity water layer by the target oil-based mud to obtain the nuclear magnetic resonance T of the oil-based mud invaded into the low-porosity water layer by the target oil-based mud 2 Spectra.
NMR T of said oil-based mud into low porosity water layer 2 In the geometric mean value correction method, preferably, nuclear magnetic resonance T of the stratum is obtained 2 Geometric mean nuclear magnetic resonance T after invasion of oil-based mud by formation 2 Of oil-based mud with geometric mean and formation invasionNuclear magnetic resonance T 2 The calculation model of the geometric mean includes:
obtaining nuclear magnetic resonance T of a plurality of simulated rock cores in a 100% water-saturated state 2 A geometric mean value;
obtaining nuclear magnetic resonance T of various simulated rock cores after invading oil-based mud 2 A geometric mean value;
obtaining NMR T of oil-based mud for simulating core invasion 2 A geometric mean value;
based on the nuclear magnetic resonance T of each simulated rock core in the 100 percent saturated water state 2 Nuclear magnetic resonance T of geometric mean value after invasion of oil-based mud 2 Nuclear magnetic resonance T of geometric mean and invaded oil-based mud 2 Geometric mean value, determining the nuclear magnetic resonance T of the formation in a 100% water-saturated state 2 Geometric mean i-formation NMR T 2 Geometric mean nuclear magnetic resonance T after invasion of oil-based mud by formation 2 Nuclear magnetic resonance T of oil-based mud with geometric mean and formation invasion 2 A calculation model of the geometric mean;
more preferably, the nuclear magnetic resonance T of a plurality of simulated cores in a 100% water-saturated state is obtained 2 The geometric mean includes:
obtaining nuclear magnetic resonance T of a plurality of simulated rock cores in a 100% water-saturated state 2 A spectrum;
based on the nuclear magnetic resonance T of each simulated rock core in a 100 percent water-saturated state 2 Spectrum, calculating the nuclear magnetic resonance T of each simulated rock core under the state of 100 percent of water saturation 2 A geometric mean value;
in one embodiment, the nuclear magnetic resonance T of a plurality of simulated cores in a 100% water-saturated state is obtained 2 The spectra include:
carrying out oil washing and salt washing treatment on the plurality of simulated rock cores;
pressurizing and soaking the rock core by using distilled water for 24 hours respectively after the oil washing and salt washing treatment so as to enable the rock core to reach a 100% water saturation state;
respectively carrying out nuclear magnetic resonance test on each simulated rock core in a 100% saturated water state to obtain each simulated rock core in the 100% saturated water stateNuclear magnetic resonance of 2 Performing spectroscopy;
more preferably, the nuclear magnetic resonance T of each simulated rock core after invading the oil-based mud is obtained 2 The geometric mean includes:
obtaining nuclear magnetic resonance T of various simulated rock cores after invading oil-based mud 2 A spectrum;
based on nuclear magnetic resonance T of various simulated rock cores after invasion of oil-based mud 2 Spectrum, calculating the nuclear magnetic resonance T of each simulated rock core after invading oil-based mud 2 A geometric mean value;
in one embodiment, the NMR T of each simulated core after invasion of the oil-based mud is obtained 2 The spectra include:
pressurizing and displacing the oil-based mud (for example, displacing for 24 hours) for each simulated core in the 100% water-saturated state, so that each simulated core invades the oil-based mud;
respectively carrying out nuclear magnetic resonance test on each simulated rock core after the simulated rock core invades the oil-based mud to obtain the nuclear magnetic resonance T of each simulated rock core after the simulated rock core invades the oil-based mud 2 Performing spectroscopy;
more preferably, the NMR T of each simulated core invaded oil-based mud is acquired 2 The geometric mean includes:
obtaining NMR T of oil-based mud for simulating core invasion 2 A spectrum;
nuclear magnetic resonance T of oil-based mud based on invasion of various simulated cores 2 Spectrum, separately calculating the NMR T of each simulated core invaded oil-based mud 2 A geometric mean value;
in one embodiment, the NMR T of each simulated core invaded oil-based mud is obtained 2 The spectra include:
performing nuclear magnetic resonance test on the oil-based mud invaded by each simulated rock core to obtain the nuclear magnetic resonance T of the oil-based mud invaded by each simulated rock core 2 Performing spectroscopy;
wherein the oil-based mud category simulating core invasion is preferably the same as the oil-based mud category targeted for invasion by the oil-based mud invading low porosity water layer;
the simulated core preferably selects a representative core of a corresponding layer in an oil reservoir to which the target oil-receiving-oil-based mud invades the low-porosity water layer;
wherein, the simulation core is preferably a plunger-shaped core with the length of more than 2.5 cm.
The preferable technical scheme is based on T of simulated rock core in 100% saturated water and oil-based mud invasion state 2 Geometric mean, T of control oil based mud 2 Geometric mean, analysis of invasion of oil-based mud versus measured nuclear magnetic resonance T 2 Influence of geometric mean, determination of NMR T that can be used to carry out invasion of oil-based mud into low porosity water layers 2 Geometric mean corrected model, i.e. nuclear magnetic resonance T of the formation 2 Geometric mean nuclear magnetic resonance T after invasion of oil-based mud by formation 2 Nuclear magnetic resonance T of oil-based mud with geometric mean and formation invasion 2 A computational model of the geometric mean.
In the preferred technical scheme, the nuclear magnetic resonance test can be carried out according to the regulation of the standard SY/T6490-2014 for nuclear magnetic resonance parameter laboratory measurement of rock samples.
NMR T of said oil-based mud into low porosity water layer 2 In the geometric mean value correction method, preferably, the nuclear magnetic resonance T of the stratum 2 Geometric mean nuclear magnetic resonance T after invasion of oil-based mud by formation 2 Nuclear magnetic resonance T of oil-based mud with geometric mean and formation invasion 2 The geometric mean calculation model is:
in the formula, T 2lm_C Nuclear magnetic resonance for formation T 2 A geometric mean value; t is 2lm_OBM NMR T for oil-based muds 2 A geometric mean value; t is 2lm_OBM_W NMR T after invasion of oil-based mud for formations 2 A geometric mean value; x and y are corrected geometric factors, and the numerical values can be obtained by calibrating the nuclear magnetic resonance experiment result of the rock core;
more preferably, the relationship between x and y in the calculation model satisfies x + y =1.0.
NMR T of said oil-based mud into low porosity water layer 2 In the geometric mean value correction method, preferably, nuclear magnetic resonance T 2 The geometric mean is determined by the following formula:
in the formula, T 2lm Is nuclear magnetic resonance T 2 Geometric mean, ms; amp (i) is nuclear magnetic resonance T 2 Spectrum ith nuclear magnetic resonance T 2 The amplitude, v/v, corresponding to the relaxation time; t is 2 (i) Is nuclear magnetic resonance T 2 Spectrum ith nuclear magnetic resonance T 2 Relaxation time, ms; n is the measured nuclear magnetic resonance T 2 The distribution number of the spectra is different for different nuclear magnetic resonance instruments, and the value of n is different;
in one embodiment, the simulated core has a nuclear magnetic resonance T at 100% water saturation 2 The geometric mean is determined by the following formula:
in the formula, T 2lm_W For simulating nuclear magnetic resonance T of rock core in 100% water-saturated state 2 Geometric mean, ms; amp _ W (i) is nuclear magnetic resonance T of simulated rock core in 100% water saturation state 2 Spectrum ith nuclear magnetic resonance T 2 The amplitude, v/v, corresponding to the relaxation time; t is a unit of 2_W (i) For simulating nuclear magnetic resonance T of rock core in 100% water-saturated state 2 Spectrum ith nuclear magnetic resonance T 2 Relaxation time, ms; n is the measured NMR T 2 The distribution number of the spectra is different for different nuclear magnetic resonance instruments, and the value of n is different;
in one embodiment, nuclear magnetic resonance T after core invasion of oil-based mud is simulated 2 The geometric mean is determined by the following formula:
in the formula, T 2lm_OBM_W For simulating nuclear magnetic resonance T after core invasion of oil-based mud 2 Geometric mean, ms; amp _ OBM _ W (i) is nuclear magnetic resonance T after simulated core invades oil-based mud 2 Spectrum ith nuclear magnetic resonance T 2 The amplitude, v/v, corresponding to the relaxation time; t is a unit of 2_OBM_W (i) For simulating nuclear magnetic resonance T after core invasion of oil-based mud 2 Spectrum ith nuclear magnetic resonance T 2 Relaxation time, ms; n is the measured nuclear magnetic resonance T 2 The distribution number of the spectra is different for different nuclear magnetic resonance instruments, and the value of n is different;
in one embodiment, NMR T of the invaded oil-based mud 2 The geometric mean is determined by the following formula:
in the formula, T 2lm_OBM NMR T for invaded oil-based muds 2 Geometric mean, ms; amp _ OBM (i) Nuclear magnetic resonance T of invaded oil-based mud 2 Spectrum ith nuclear magnetic resonance T 2 The amplitude, v/v, corresponding to the relaxation time; t is a unit of 2_OBM (i) NMR T for invaded oil-based mud 2 Spectrum ith nuclear magnetic resonance T 2 Relaxation time, ms; n is the measured nuclear magnetic resonance T 2 The distribution number of the spectra is different for different nuclear magnetic resonance instruments.
The invention also provides a nuclear magnetic resonance T method for invasion of oil-based mud into low-porosity water layer 2 A geometric mean correction system, wherein the system comprises:
target layer T 2 A geometric mean acquisition module: nuclear magnetic resonance T for acquiring invasion of target oil-bearing mud into low-porosity water layer 2 A geometric mean value;
oil-based mud T 2 A geometric mean acquisition module: nuclear magnetic resonance T for acquiring invasion oil-based mud in low-porosity water layer invaded by oil-based mud 2 A geometric mean value;
a model acquisition module: for obtaining nuclear magnetic resonance T of formation 2 Geometric mean nuclear magnetic resonance T after invasion of oil-based mud by formation 2 Nuclear magnetic resonance T of oil-based mud with geometric mean and formation invasion 2 A calculation model of a geometric mean;
T 2 a geometric mean correction module: nuclear magnetic resonance T for invasion of low porosity water layer based on target oil-bearing mud 2 Nuclear magnetic resonance T of geometric mean value and target oil-base mud invaded into low-porosity water layer 2 Geometric mean, using nuclear magnetic resonance T of the formation 2 Geometric mean nuclear magnetic resonance T after invasion of oil-based mud by formation 2 Nuclear magnetic resonance T of geometric mean and invaded oil-based mud 2 A calculation model of a geometric mean value is used for determining the nuclear magnetic resonance T of a 100% water-saturated state of a stratum with a target invaded by oil-based mud into a low-porosity water layer 2 Geometric mean value, thereby completing the nuclear magnetic resonance T of the target oil-bearing mud invading the low-porosity water layer 2 And correcting the geometric mean value.
NMR T of said oil-based mud into low porosity water layer 2 In the geometric mean correction model, the low porosity is preferably a porosity of not more than 15%.
NMR T of said oil-based mud into low porosity water layer 2 In the geometric mean value correction model, the target layer T is preferably 2 The geometric mean acquisition module comprises:
nuclear magnetic resonance logging of target zone T 2 A spectrum acquisition submodule: nuclear magnetic resonance logging T for acquiring invasion of target oil-bearing mud into low-porosity water layer 2 A spectrum;
target layer T 2 Geometric mean determination submodule: nuclear magnetic resonance logging T for invasion of low porosity water layer based on target oil-bearing mud 2 Spectrum, nuclear magnetic resonance T for determining invasion of target oil-bearing mud into low-porosity water layer 2 Geometric mean.
NMR T of said oil-based mud into low porosity water layer 2 In the geometric mean correction method, preferably, the oil-based mud T 2 Geometric mean acquisition moduleThe method comprises the following steps:
oil-based mud T 2 A spectrum acquisition submodule: nuclear magnetic resonance T for acquiring invasion oil-based mud in low-porosity water layer invaded by oil-based mud 2 A spectrum;
oil-based mud T 2 Geometric mean determination submodule: nuclear magnetic resonance T for invasion of oil-based mud based on invasion of target oil-based mud into low porosity water layer 2 Spectroscopy, determining the NMR T of the target oil-based mud invaded into the low porosity water layer 2 A geometric mean value;
in one embodiment, the target is subject to nuclear magnetic resonance T of invasion of oil-based mud into low porosity water layer 2 Nuclear magnetic resonance T obtained by nuclear magnetic resonance test of oil-based mud with spectrum as target and invaded by oil-based mud invaded into low-porosity water layer 2 Spectra.
NMR T of said oil-based mud into low porosity water layer 2 In the geometric mean value correction model, preferably, the model obtaining module includes:
a first data acquisition sub-module: used for obtaining nuclear magnetic resonance T of a plurality of simulated rock cores in a 100% water-saturated state 2 A geometric mean value;
the second data acquisition sub-module: nuclear magnetic resonance T for obtaining simulated rock cores after invading oil-based mud 2 A geometric mean value;
a third data acquisition sub-module: nuclear magnetic resonance T for obtaining oil-based mud simulating core invasion 2 A geometric mean value;
a model determination submodule: for nuclear magnetic resonance T based on respective simulated cores in a 100% water-saturated state 2 Nuclear magnetic resonance T of geometric mean value after invasion of oil-based mud 2 Nuclear magnetic resonance T of geometric mean and invaded oil-based mud 2 Geometric mean value, determining the nuclear magnetic resonance T of the formation in a 100% water-saturated state 2 Geometric mean i-formation nuclear magnetic resonance T 2 Geometric mean nuclear magnetic resonance T after invasion of oil-based mud by formation 2 Nuclear magnetic resonance T of oil-based mud with geometric mean and formation invasion 2 A calculation model of the geometric mean;
more preferably, the first data acquisition sub-module includes:
first T of simulated rock core 2 A spectrum acquisition unit: used for obtaining nuclear magnetic resonance T of a plurality of simulated rock cores in a 100% water-saturated state 2 A spectrum;
first T of simulated rock core 2 A geometric mean determination unit: for nuclear magnetic resonance T based on each simulated core in 100% water-saturated state 2 Spectrum, calculating the nuclear magnetic resonance T of each simulated rock core under the state of 100 percent of water saturation 2 A geometric mean value;
in a specific embodiment, the multiple simulated cores have a nuclear magnetic resonance T at 100% water saturation 2 The spectrum is a nuclear magnetic resonance T obtained by washing a plurality of simulated rock cores with oil and salt, then carrying out pressure soaking (for example, 24 hours) by using distilled water so as to enable the simulated rock cores to reach a 100% saturated water state, and carrying out a nuclear magnetic resonance test in the 100% saturated water state 2 A spectrum;
more preferably, the second data acquisition submodule includes:
second T of simulated core 2 A spectrum acquisition unit: nuclear magnetic resonance T for obtaining simulated rock cores after invading oil-based mud 2 Performing spectroscopy;
second T of simulated core 2 A geometric mean determination unit: nuclear magnetic resonance T used after invasion of oil-based mud based on various simulated cores 2 Spectrum, respectively calculating the nuclear magnetic resonance T of each simulated rock core after invading oil-based mud 2 A geometric mean value;
in one embodiment, nuclear magnetic resonance T of each simulated core after invasion of oil-based mud 2 NMR T obtained by NMR testing after invasion of oil-based mud by pressure displacement (for example, 24 hours) of oil-based mud from each mock core having spectrum in 100% water-saturated state 2 A spectrum;
more preferably, the third data acquisition submodule includes:
simulation oil-based mud T 2 A spectrum acquisition unit: nuclear magnetic resonance T for obtaining oil-based mud simulating core invasion 2 Performing spectroscopy;
simulation oil-based mud T 2 A geometric mean determination unit: nuclear magnetic resonance T for oil-based mud based on simulated core invasion 2 Spectrum, separately calculating the NMR T of each simulated core invaded oil-based mud 2 A geometric mean value;
in one embodiment, each simulated core invaded oil-based mud has a nuclear magnetic resonance T 2 Nuclear magnetic resonance T obtained by nuclear magnetic resonance testing of oil-based mud with spectrum for simulating core invasion 2 A spectrum;
wherein the oil-based mud category simulating core invasion is preferably the same as the oil-based mud category targeted for invasion by the oil-based mud invading low porosity water layer;
the simulated core preferably uses a representative core of a corresponding layer in an oil reservoir to which the target oil-receiving-oil-based mud invades the low-porosity water layer;
wherein, the simulated core is preferably a plunger-shaped core with the length of more than 2.5 cm.
NMR T of said oil-based mud into low porosity water layer 2 In the geometric mean value correction model, the nuclear magnetic resonance T of the stratum is preferably 2 Geometric mean nuclear magnetic resonance T after invasion of oil-based mud by formation 2 Nuclear magnetic resonance T of oil-based mud with geometric mean and formation invasion 2 The geometric mean calculation model is:
in the formula, T 2lm_C Nuclear magnetic resonance for formation T 2 A geometric mean value; t is 2lm_OBM NMR T for oil-based mud 2 A geometric mean value; t is a unit of 2lm_OBM_W NMR T after invasion of oil-based mud for formations 2 A geometric mean value; x and y are corrected geometric factors, and the numerical values of the x and y can be obtained by calibrating the nuclear magnetic resonance experiment result of the rock core;
more preferably, the relationship between x and y in the calculation model satisfies x + y =1.0.
NMR T of said oil-based mud into low porosity water layer 2 In the geometric mean value correction model, preferably, nuclear magnetic resonance T 2 The geometric mean is determined by the following formula:
in the formula, T 2lm Is nuclear magnetic resonance T 2 Geometric mean, ms; amp (i) is nuclear magnetic resonance T 2 Spectrum ith nuclear magnetic resonance T 2 The amplitude, v/v, corresponding to the relaxation time; t is 2 (i) Is nuclear magnetic resonance T 2 Spectrum ith nuclear magnetic resonance T 2 Relaxation time, ms; n is the measured NMR T 2 The distribution number of the spectra is different for different nuclear magnetic resonance instruments, and the value of n is different;
in one embodiment, the mock core exhibits a nuclear magnetic resonance T at 100% water saturation 2 The geometric mean is determined by the following formula:
in the formula, T 2lm_W For simulating nuclear magnetic resonance T of rock core in 100% water-saturated state 2 Geometric mean, ms; amp _ W (i) is nuclear magnetic resonance T of simulated rock core in 100% water saturation state 2 Spectrum ith nuclear magnetic resonance T 2 The amplitude, v/v, corresponding to the relaxation time; t is 2_W (i) Is a nuclear magnetic resonance T of a simulated rock core in a 100 percent saturated water state 2 Spectrum ith nuclear magnetic resonance T 2 Relaxation time, ms; n is the measured nuclear magnetic resonance T 2 The distribution number of the spectra is different for different nuclear magnetic resonance instruments, and the value of n is different;
in one embodiment, nuclear magnetic resonance T after core invasion of oil-based mud is simulated 2 The geometric mean is determined by the following formula:
in the formula, T 2lm_OBM_W For simulating nuclear magnetic resonance T after core invasion of oil-based mud 2 Geometric mean, ms; amp _ OBM-W (i) is nuclear magnetic resonance T after simulating core invasion of oil-based mud 2 Spectrum ith nuclear magnetic resonance T 2 The amplitude, v/v, corresponding to the relaxation time; t is a unit of 2_OBM_W (i) For simulating nuclear magnetic resonance T after core invasion of oil-based mud 2 Spectrum ith nuclear magnetic resonance T 2 Relaxation time, ms; n is the measured nuclear magnetic resonance T 2 The distribution number of the spectra is different for different nuclear magnetic resonance instruments, and the value of n is different;
in one embodiment, NMR T of the invaded oil-based mud 2 The geometric mean is determined by the following formula:
in the formula, T 2lm_OBM NMR T for invaded oil-based mud 2 Geometric mean, ms; amp _ OBM (i) is nuclear magnetic resonance T of invaded oil-based mud 2 Spectrum ith nuclear magnetic resonance T 2 The amplitude, v/v, corresponding to the relaxation time; t is a unit of 2_OBM (i) NMR T for invaded oil-based mud 2 Spectrum ith nuclear magnetic resonance T 2 Relaxation time, ms; n is the measured nuclear magnetic resonance T 2 The distribution number of the spectra is different for different nuclear magnetic resonance instruments.
The technical scheme provided by the invention utilizes nuclear magnetic resonance T of stratum 2 Geometric mean nuclear magnetic resonance T after invasion of oil-based mud by formation 2 Nuclear magnetic resonance T of oil-based mud with geometric mean and formation invasion 2 Geometric mean calculation model, nuclear magnetic resonance T actually measured for water layer affected by invasion of oil-based mud 2 The geometric mean is corrected to obtain the NMR T at 100% water-saturated state of the actual water layer affected by the invasion of the oil-based mud 2 Geometric mean, nuclear magnetic resonance T obtained after correction 2 The geometric mean value can represent the pore structure and permeability of the stratum more accurately. The technical scheme provided by the invention effectively solves the problem of invasion of oil-based mudNMR T of affected low porosity water layer directly calculated from NMR well log data 2 The geometric mean value cannot reflect the problem of the real condition of the stratum.
Drawings
In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings required to be used in the description of the embodiments are briefly introduced below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and other drawings can be obtained by those skilled in the art without creative efforts based on the drawings:
FIG. 1 shows NMR T of oil-based mud into a low porosity water layer according to an embodiment of the invention 2 The flow chart of the geometric mean value correction method is shown schematically.
FIG. 2 shows NMR T of oil-based mud into a low porosity water layer according to an embodiment of the invention 2 A frame diagram of a geometric mean correction system.
Fig. 3 is a schematic flow chart of the computational model acquisition step in example 1.
FIG. 4 shows the NMR T of the oil-based mud after the 100% saturation of the 1 simulated core in example 1 and after invasion of the oil-based mud 2 And (4) a spectrogram.
FIG. 5 shows the NMR T values of 10 simulated cores of example 1 after 100% saturation and invasion of oil-based mud 2 Nuclear magnetic resonance T of spectral calculation 2 Geometric mean comparison plot.
FIG. 6 is the NMR T at 100% saturation of 10 simulated cores from example 1 2 Nuclear magnetic resonance T after correction of geometric mean and invasion oil-based mud 2 Geometric mean comparison plot.
Detailed Description
In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be described in detail and completely with reference to the drawings in the embodiments of the present invention. It should be apparent that the described embodiments are only some of the embodiments of the present invention, and not all of them. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
Referring to FIG. 1, one embodiment of the present invention provides a NMR T of oil-based mud into a low porosity water layer 2 A geometric mean correction method, wherein the method comprises:
step S1: obtaining nuclear magnetic resonance T of target oil-bearing mud invading low-porosity water layer 2 A geometric mean value;
step S2: obtaining nuclear magnetic resonance T of invasion oil-based mud in low-porosity water layer invaded by target oil-based mud 2 A geometric mean value;
and step S3: obtaining nuclear magnetic resonance T of formation 2 Geometric mean nuclear magnetic resonance T after invasion of oil-based mud by formation 2 Nuclear magnetic resonance T of oil-based mud with geometric mean and formation invasion 2 A calculation model of a geometric mean;
and step S4: nuclear magnetic resonance T based on invasion of target oil-bearing mud into low-porosity water layer 2 Nuclear magnetic resonance T of geometric mean value and target oil-base mud invaded into low-porosity water layer 2 Geometric mean, using nuclear magnetic resonance T of the formation 2 Geometric mean nuclear magnetic resonance T after invasion of oil-based mud by formation 2 Nuclear magnetic resonance T of geometric mean and invaded oil-based mud 2 A calculation model of a geometric mean value is used for determining the nuclear magnetic resonance T of a 100% water-saturated state of a stratum with a target invaded by oil-based mud into a low-porosity water layer 2 Geometric mean value, thereby completing the nuclear magnetic resonance T of the target oil-bearing mud invading the low-porosity water layer 2 And correcting the geometric mean value.
Further, low porosity means that the porosity does not exceed 15%.
Further, step S1 includes:
step S11: nuclear magnetic resonance logging T for acquiring invasion of target oil-bearing mud into low-porosity water layer 2 A spectrum;
step S12: nuclear magnetic resonance logging T based on invasion of target oil-bearing mud into low-porosity water layer 2 Spectrum, determining target subjectNuclear magnetic resonance T of oil-based mud invading low-porosity water layer 2 Geometric mean.
Further, step S2 includes:
step S21: obtaining nuclear magnetic resonance T of invasion oil-based mud in low-porosity water layer invaded by target oil-based mud 2 A spectrum;
step S22: nuclear magnetic resonance T based on invasion of target oil-bearing mud into low-porosity water layer 2 Spectroscopy, determining the NMR T of the target oil-based mud invaded into the low porosity water layer 2 A geometric mean value;
wherein the target is subjected to nuclear magnetic resonance T of invasion of oil-based mud into the low-porosity water layer 2 The spectrum is preferably the nuclear magnetic resonance T of the target oil-bearing mud invading oil-bearing mud in a low-porosity water layer 2 Nuclear magnetic resonance T obtained by nuclear magnetic resonance test of oil-based mud with spectrum as target and invaded by oil-based mud into low-porosity water layer 2 A spectrum;
specifically, acquiring nuclear magnetic resonance T of oil-based mud invaded by target oil-based mud into low-porosity water layer 2 The spectra can be achieved by:
performing nuclear magnetic resonance test on the oil-based mud invaded into the low-porosity water layer by the target oil-based mud to obtain the nuclear magnetic resonance T invaded into the oil-based mud in the low-porosity water layer invaded by the target oil-based mud 2 Spectra.
Further, step S3 includes:
step S31: obtaining nuclear magnetic resonance T of a plurality of simulated rock cores in a 100% water-saturated state 2 A geometric mean value;
step S32: obtaining nuclear magnetic resonance T of various simulated rock cores after invading oil-based mud 2 A geometric mean value;
step S33: obtaining NMR T of oil-based mud for simulating core invasion 2 A geometric mean value;
step S34: based on the nuclear magnetic resonance T of each simulated rock core in the 100 percent saturated water state 2 Nuclear magnetic resonance T of geometric mean value after invasion of oil-based mud 2 Geometric meanAnd NMR T of invaded oil-based mud 2 Geometric mean value, determining the nuclear magnetic resonance T of the formation in a 100% water-saturated state 2 Geometric mean i-formation nuclear magnetic resonance T 2 Geometric mean nuclear magnetic resonance T after invasion of oil-based mud by formation 2 Nuclear magnetic resonance T of oil-based mud with geometric mean and formation invasion 2 A calculation model of the geometric mean;
further, step S31 includes:
step S311: obtaining nuclear magnetic resonance T of a plurality of simulated rock cores in a 100% saturated water state 2 A spectrum;
step S312: based on the nuclear magnetic resonance T of each simulated rock core in a 100 percent water-saturated state 2 Spectrum, calculating the nuclear magnetic resonance T of each simulated rock core under the state of 100 percent of water saturation 2 A geometric mean value;
wherein the nuclear magnetic resonance T of the plurality of simulated rock cores in a 100% water-saturated state 2 The spectrum is preferably a nuclear magnetic resonance T obtained by washing a plurality of simulated cores with oil and salt, then soaking the cores in distilled water under pressure (for example, for 24 hours) so as to achieve a 100% saturated water state, and performing a nuclear magnetic resonance test in the 100% saturated water state 2 A spectrum;
specifically, nuclear magnetic resonance T of a plurality of simulated cores in a 100% water-saturated state is obtained 2 The spectra can be achieved by:
carrying out oil washing and salt washing treatment on the plurality of simulated rock cores;
pressurizing and soaking the rock core by using distilled water for 24 hours respectively after the oil washing and salt washing treatment so as to enable the rock core to reach a 100% water saturation state;
respectively carrying out nuclear magnetic resonance test on each simulated rock core in a 100% saturated water state to obtain nuclear magnetic resonance T of each simulated rock core in the 100% saturated water state 2 A spectrum;
further, step S32 includes:
step S321: obtaining nuclear magnetic resonance T of simulated rock cores after invasion of oil-based mud 2 A spectrum;
step S322: based on respective simulated core invasionNuclear magnetic resonance T after oil-based mud 2 Spectrum, calculating the nuclear magnetic resonance T of each simulated rock core after invading oil-based mud 2 A geometric mean value;
wherein the nuclear magnetic resonance T of each simulated rock core after invading the oil-based mud 2 The spectra are preferably nuclear magnetic resonance T obtained by performing pressurized displacement (for example, 24 hours) of the oil-based mud on each mock core in a 100% water-saturated state so as to allow invasion of the oil-based mud and then performing nuclear magnetic resonance testing 2 A spectrum;
specifically, the nuclear magnetic resonance T of each simulated rock core after invading oil-based mud is obtained 2 The spectra can be achieved by:
pressurizing and displacing the oil-based mud (for example, displacing for 24 hours) for each simulated core in the 100% water-saturated state, so that each simulated core invades the oil-based mud;
respectively carrying out nuclear magnetic resonance test on each simulated rock core after the simulated rock core invades the oil-based mud to obtain the nuclear magnetic resonance T of each simulated rock core after the simulated rock core invades the oil-based mud 2 A spectrum;
in the preferred technical scheme, the invasion amount of the oil-based mud of each simulated rock core does not need to be additionally controlled, and the invasion amount can be identified by a nuclear magnetic resonance test;
further, step S33 includes:
step S331: obtaining nuclear magnetic resonance T of oil-based mud for simulating core invasion 2 A spectrum;
step S332: nuclear magnetic resonance T of oil-based mud based on invasion of various simulated cores 2 Spectrum, separately calculating the NMR T of each simulated core invaded oil-based mud 2 A geometric mean value;
wherein each simulated core invaded oil-based mud NMR T 2 The spectrum is preferably nuclear magnetic resonance T obtained by performing nuclear magnetic resonance test on oil-based mud simulating core invasion 2 A spectrum;
specifically, nuclear magnetic resonance T of oil-based mud simulating core invasion is acquired 2 The spectra can be achieved by:
performing nuclear magnetic resonance measurement on oil-based mud invaded by each simulated rock coreTesting to obtain the nuclear magnetic resonance T of the oil-based mud for simulating the invasion of the rock core 2 Spectra.
Wherein the oil-based mud specie simulating core invasion is preferably the same as the oil-based mud specie targeted for invasion by an oil-based mud-invaded low porosity water layer.
And preferably selecting a representative core of a corresponding layer in an oil deposit to which the target oil-bearing mud invades the low-porosity water layer.
Wherein, the simulated core is preferably a plunger-shaped core with the length of more than 2.5 cm.
The preferable technical scheme is based on T of simulated rock core in 100% saturated water and oil-based mud invasion state 2 Geometric mean, T of control oil-based mud 2 Geometric mean, analysis of invasion of oil-based mud versus measured NMR T 2 Influence of geometric mean, determination of NMR T that can be used to carry out invasion of oil-based mud into low porosity water layers 2 Geometric mean corrected model, i.e. nuclear magnetic resonance T of the formation 2 Geometric mean nuclear magnetic resonance T after invasion of oil-based mud by formation 2 Nuclear magnetic resonance T of oil-based mud with geometric mean and formation invasion 2 A computational model of the geometric mean.
The nuclear magnetic resonance test can be carried out according to the standard regulation of rock sample nuclear magnetic resonance parameter laboratory measurement specification SY/T6490-2014.
Further, nuclear magnetic resonance T of stratum 2 Geometric mean nuclear magnetic resonance T after invasion of oil-based mud by formation 2 Nuclear magnetic resonance T of oil-based mud with geometric mean and formation invasion 2 The geometric mean calculation model is:
in the formula, T 2lm_C Nuclear magnetic resonance for formation T 2 A geometric mean value; t is 2lm_OBM NMR T for oil-based mud 2 A geometric mean value; t is 2lm_OBM_W NMR T after invasion of oil-based mud for formations 2 A geometric mean value; x and y are correctedThe numerical value of the factor can be obtained by calibrating the nuclear magnetic resonance experiment result of the rock core;
further, the relationship between x and y in the calculation model satisfies x + y =1.0.
For example, step S3 obtains nuclear magnetic resonance T of formation 2 Geometric mean nuclear magnetic resonance T after invasion of oil-based mud by formation 2 Nuclear magnetic resonance T of oil-based mud with geometric mean and formation invasion 2 The calculation model of the geometric mean includes:
1) Acquiring a plurality of representative cores of corresponding positions in an oil reservoir to which a target oil-bearing-based mud invades a low-porosity water layer, and preparing a plunger-shaped core with the length of more than 2.5cm as a simulated core;
2) Carrying out oil washing and salt washing treatment on each simulated rock core; pressurizing and soaking the rock core by using distilled water for 24 hours respectively after the oil washing and salt washing treatment so as to enable the rock core to reach a 100% water saturation state; respectively carrying out nuclear magnetic resonance test on each simulated rock core in a 100% saturated water state to obtain nuclear magnetic resonance T of each simulated rock core in the 100% saturated water state 2 Performing spectroscopy; based on the nuclear magnetic resonance T of each simulated rock core in a 100% water-saturated state 2 Spectrum, calculating the nuclear magnetic resonance T of each simulated rock core under the state of 100 percent of water saturation 2 A geometric mean value;
3) Preparing oil-based mud for simulation experiment, which has the same type as that of the oil-based mud invaded by the low-porosity water layer invaded by the target oil-based mud; respectively carrying out pressurization displacement (for example, displacement for 24 hours) of oil-based mud for a simulation experiment on each simulated core in a 100% water-saturated state, so that each simulated core invades the oil-based mud; respectively carrying out nuclear magnetic resonance test on each simulated rock core after the simulated rock core invades the oil-based mud to obtain the nuclear magnetic resonance T of each simulated rock core after the simulated rock core invades the oil-based mud 2 A spectrum; and based on the nuclear magnetic resonance T of each simulated rock core after invading the oil-based mud 2 Spectrum, calculating the nuclear magnetic resonance T of each simulated rock core after invading oil-based mud 2 A geometric mean value;
4) Performing nuclear magnetic resonance test on the prepared oil-based mud for the simulation experiment to obtain the nuclear magnetic resonance of the oil-based mud for simulating the invasion of the rock coreVibrating T 2 A spectrum; and based on the nuclear magnetic resonance T of the oil-based mud of each simulated core invasion 2 Spectrum, separately calculating the NMR T of each simulated core invaded oil-based mud 2 A geometric mean value;
5) Based on nuclear magnetic resonance T of each simulated rock core in 100% water-saturated state 2 Nuclear magnetic resonance T of geometric mean value after invasion of oil-based mud 2 Nuclear magnetic resonance T of geometric mean and invaded oil-based mud 2 Geometric mean value, calibration of nuclear magnetic resonance T of 100% water-saturated formation 2 Geometric mean i-formation NMR T 2 Geometric mean nuclear magnetic resonance T after invasion of oil-based mud by formation 2 Nuclear magnetic resonance T of oil-based mud with geometric mean and formation invasion 2 Calculation model of geometric mean
The geometric factors x and y in the formation are obtained, thereby realizing the nuclear magnetic resonance T in the 100% water-saturated state of the formation 2 Geometric mean i-formation NMR T 2 Geometric mean nuclear magnetic resonance T after invasion of oil-based mud by formation 2 Nuclear magnetic resonance T of oil-based mud with geometric mean and formation invasion 2 Determining a calculation model of the geometric mean value;
in the calculation model, T 2lm_C Nuclear magnetic resonance for formation T 2 A geometric mean value; t is a unit of 2lm_OBM NMR T for oil-based mud 2 A geometric mean value; t is 2lm_OBM_W NMR T after invasion of oil-based mud for formations 2 A geometric mean value; x and y are geometric factors for correction, and the relationship between x and y satisfies x + y =1.0.
Further, nuclear magnetic resonance T 2 The geometric mean is determined by the following formula:
in the formula, T 2lm Is nuclear magnetic resonance T 2 Geometric mean, ms; amp (i) is NMR T 2 Spectrum ith nuclear magnetic resonance T 2 Relaxation time periodCorresponding amplitude, v/v; t is a unit of 2 (i) Is nuclear magnetic resonance T 2 Spectrum ith nuclear magnetic resonance T 2 Relaxation time, ms; n is the measured nuclear magnetic resonance T 2 The distribution number of the spectra is different for different nuclear magnetic resonance instruments, and the value of n is different;
for example, the simulated core has a nuclear magnetic resonance T at 100% water saturation 2 The geometric mean is determined by the following equation:
in the formula, T 2lm_W Is a nuclear magnetic resonance T of a simulated rock core in a 100 percent saturated water state 2 Geometric mean, ms; amp _ W (i) is nuclear magnetic resonance T of simulated rock core in 100% water saturation state 2 Spectrum ith nuclear magnetic resonance T 2 The amplitude, v/v, corresponding to the relaxation time; t is 2_W (i) For simulating nuclear magnetic resonance T of rock core in 100% water-saturated state 2 Spectrum ith nuclear magnetic resonance T 2 Relaxation time, ms; n is the measured nuclear magnetic resonance T 2 The distribution number of the spectra is different for different nuclear magnetic resonance instruments, and the value of n is different;
for example, nuclear magnetic resonance T after simulating invasion of rock core into oil-based mud 2 The geometric mean is determined by the following formula:
in the formula, T 2lm_OBM_W For simulating nuclear magnetic resonance T after core invasion of oil-based mud 2 Geometric mean, ms; amp _ OBM _ W (i) is nuclear magnetic resonance T after simulating invasion of rock core into oil-based mud 2 Spectrum ith nuclear magnetic resonance T 2 The amplitude, v/v, corresponding to the relaxation time; t is 2_OBM_W (i) For simulating nuclear magnetic resonance T after core invasion of oil-based mud 2 Spectrum ith nuclear magnetic resonance T 2 Relaxation time, ms; n is the measured nuclear magnetic resonance T 2 The distribution number of the spectra is different for different nuclear magnetic resonance instruments, and the value of n is different;
for example, nuclear magnetic resonance T of invaded oil-based mud 2 The geometric mean is determined by the following formula:
in the formula, T 2lm_OBM NMR T for invaded oil-based muds 2 Geometric mean, ms; amp _ OBM (i) is nuclear magnetic resonance T of invaded oil-based mud 2 Spectrum ith nuclear magnetic resonance T 2 The amplitude, v/v, corresponding to the relaxation time; t is 2_OBM (i) NMR T for invaded oil-based mud 2 Spectrum ith nuclear magnetic resonance T 2 Relaxation time, ms; n is the measured nuclear magnetic resonance T 2 The distribution number of the spectra is different for different nuclear magnetic resonance instruments.
The embodiment of the invention also provides a nuclear magnetic resonance T of the oil-based mud invading the low-porosity water layer 2 A geometric mean correction system, preferably for implementing the above-described method embodiments.
FIG. 2 is a nuclear magnetic resonance T of oil-based mud invading a low porosity water layer according to an embodiment of the invention 2 A structural block diagram of a geometric mean value correction system, as shown in fig. 2, the system includes:
target layer T 2 Geometric mean acquisition module 21: nuclear magnetic resonance T for acquiring invasion of target oil-bearing mud into low-porosity water layer 2 A geometric mean value;
oil-based mud T 2 Geometric mean acquisition module 22: nuclear magnetic resonance T for acquiring invasion oil-based mud in low-porosity water layer invaded by oil-based mud 2 A geometric mean value;
the model acquisition module 23: for obtaining nuclear magnetic resonance T of earth formation 2 Geometric mean nuclear magnetic resonance T after invasion of oil-based mud by formation 2 Nuclear magnetic resonance T of oil-based mud with geometric mean and formation invasion 2 A calculation model of the geometric mean;
T 2 geometric mean correction module 24: for low invasion by oil-based mud based on the targetNuclear magnetic resonance T of porous water layer 2 Nuclear magnetic resonance T of geometric mean value and target oil-base mud invaded into low-porosity water layer 2 Geometric mean, using nuclear magnetic resonance T of the formation 2 Geometric mean nuclear magnetic resonance T after invasion of oil-based mud by formation 2 Nuclear magnetic resonance T of geometric mean and invaded oil-based mud 2 A calculation model of a geometric mean value is used for determining the nuclear magnetic resonance T of the stratum with the low porosity water layer invaded by the oil-based mud under the 100% water saturation state 2 Geometric mean value, thereby completing the nuclear magnetic resonance T of the target oil-bearing mud invading the low-porosity water layer 2 And correcting the geometric mean value.
Further, low porosity is porosity of not more than 15%.
Further, a target layer T 2 The geometric mean acquisition module 21 includes:
nuclear magnetic resonance logging of target zone T 2 The spectrum acquisition sub-module 211: nuclear magnetic resonance logging T for acquiring invasion of target oil-bearing mud into low-porosity water layer 2 Performing spectroscopy;
target layer T 2 Geometric mean determination submodule 212: nuclear magnetic resonance logging T for invasion of low porosity water layer based on target oil-bearing mud 2 Spectrum, nuclear magnetic resonance T for determining invasion of target oil-bearing mud into low-porosity water layer 2 Geometric mean.
Further, oil-based mud T 2 The geometric mean acquisition module 22 includes:
oil-based mud T 2 The spectrum acquisition sub-module 221: nuclear magnetic resonance T for acquiring invasion oil-based mud in low-porosity water layer invaded by oil-based mud 2 A spectrum;
oil-based mud T 2 Geometric mean determination submodule 222: nuclear magnetic resonance T for invasion of oil-based mud based on invasion of target oil-bearing mud into low porosity water layer 2 Spectroscopy, determining the NMR T of the target oil-based mud invaded into the low porosity water layer 2 A geometric mean value;
wherein the target is subjected to nuclear magnetic resonance T of invasion of the oil-based mud into the low porosity water layer 2 The spectrum is preferably nuclear magnetic resonance T obtained by performing nuclear magnetic resonance test on oil-based mud invaded from low-porosity water layer by oil-based mud 2 Spectra.
Further, the model obtaining module 23 includes:
the first data acquisition sub-module 231: used for obtaining nuclear magnetic resonance T of a plurality of simulated rock cores in a 100% water-saturated state 2 A geometric mean value;
the second data acquisition sub-module 232: nuclear magnetic resonance T for obtaining simulated rock cores after invading oil-based mud 2 A geometric mean value;
the third data acquisition sub-module 233: nuclear magnetic resonance T for obtaining oil-based mud simulating core invasion 2 A geometric mean value;
model determination submodule 234: for nuclear magnetic resonance T based on respective simulated cores in a 100% water-saturated state 2 Nuclear magnetic resonance T of geometric mean value after invasion of oil-based mud 2 Nuclear magnetic resonance T of geometric mean and invaded oil-based mud 2 Geometric mean value, determining the nuclear magnetic resonance T of the formation in a 100% water-saturated state 2 Geometric mean i-formation nuclear magnetic resonance T 2 Geometric mean nuclear magnetic resonance T after invasion of oil-based mud by formation 2 Nuclear magnetic resonance T of oil-based mud with geometric mean and formation invasion 2 A calculation model of a geometric mean;
further, the first data acquisition sub-module 231 includes:
first T of simulated rock core 2 Spectrum acquisition unit 2311: used for obtaining nuclear magnetic resonance T of a plurality of simulated rock cores in a 100% saturated water state 2 A spectrum;
first T of simulated rock core 2 Geometric mean determination unit 2312: for nuclear magnetic resonance T based on each simulated rock core in 100% water-saturated state 2 Spectrum, calculating the nuclear magnetic resonance T of each simulated rock core under the state of 100 percent of water saturation 2 A geometric mean value;
wherein the nuclear magnetic resonance T of the plurality of simulated rock cores in a 100% saturated water state 2 The spectrum is preferably that a plurality of simulated cores are subjected to oil washing and salt washing treatment and then are subjected to pressure soaking by using distilled water (E.g., 24 hours) to achieve 100% saturated water and performing nmr testing in this 100% saturated water state 2 A spectrum;
further, the second data obtaining sub-module 232 includes:
second T of simulated core 2 Spectrum acquisition unit 2321: nuclear magnetic resonance T for obtaining simulated rock cores after invading oil-based mud 2 A spectrum;
second T of simulated core 2 Geometric mean determination unit 2322: nuclear magnetic resonance T used after invasion of oil-based mud based on various simulated rock cores 2 Spectrum, calculating the nuclear magnetic resonance T of each simulated rock core after invading oil-based mud 2 A geometric mean value;
wherein the nuclear magnetic resonance T of each simulated rock core after invading the oil-based mud 2 Spectra are preferably nuclear magnetic resonance (T) obtained by performing an oil-based mud pressurized displacement (e.g., 24 hours) of each mock core in a 100% water-saturated state to allow invasion of the oil-based mud followed by a nuclear magnetic resonance test 2 A spectrum;
further, the third data acquisition submodule 233 includes:
simulation oil-based mud T 2 Spectrum acquisition unit 2331: nuclear magnetic resonance T for obtaining oil-based mud simulating core invasion 2 A spectrum;
simulation oil-based mud T 2 Geometric mean determination unit 2332: nuclear magnetic resonance T for oil-based mud based on simulated core invasion 2 Spectrum, separately calculating the NMR T of each simulated core invaded oil-based mud 2 A geometric mean value;
wherein each simulated core invaded oil-based mud NMR T 2 The spectrum is preferably nuclear magnetic resonance T obtained by performing nuclear magnetic resonance test on oil-based mud invading into each simulated rock core 2 Spectra.
Wherein the oil-based mud category simulating core invasion is preferably the same as the oil-based mud category targeted for invasion by the oil-based mud invading low porosity water layer;
the simulation core preferably selects a representative core of a corresponding layer in an oil reservoir to which a target oil-bearing mud invades a low-porosity water layer;
wherein, the simulated core is preferably a plunger-shaped core with the length of more than 2.5 cm.
Further, nuclear magnetic resonance T of stratum 2 Geometric mean nuclear magnetic resonance T after invasion of oil-based mud by formation 2 Nuclear magnetic resonance T of oil-based mud with geometric mean and formation invasion 2 The geometric mean calculation model is:
in the formula, T 2lm_C Nuclear magnetic resonance for formation T 2 A geometric mean value; t is 2lm_OBM NMR T for oil-based mud 2 A geometric mean value; t is 2lm_OBM_W NMR T after invasion of oil-based mud for formations 2 A geometric mean value; x and y are corrected geometric factors, and the numerical values can be obtained by calibrating the nuclear magnetic resonance experiment result of the rock core;
further, the relationship between x and y in the calculation model satisfies x + y =1.0.
Further, nuclear magnetic resonance T 2 The geometric mean is determined by the following formula:
in the formula, T 2lm Is nuclear magnetic resonance T 2 Geometric mean, ms; amp (i) is NMR T 2 Spectrum ith nuclear magnetic resonance T 2 The amplitude, v/v, corresponding to the relaxation time; t is 2 (i) Is nuclear magnetic resonance T 2 Spectrum ith nuclear magnetic resonance T 2 Relaxation time, ms; n is the measured NMR T 2 The distribution number of the spectra is different for different nuclear magnetic resonance instruments, and the value of n is different;
for example, the simulated core has a nuclear magnetic resonance T at 100% water saturation 2 The geometric mean is determined by the following formula:
in the formula, T 2lm_W Nuclear magnetic resonance T of simulated core in 100% water-saturated state 2 Geometric mean, ms; amp _ W (i) is nuclear magnetic resonance T of simulated rock core in 100% water saturation state 2 Spectrum ith nuclear magnetic resonance T 2 The amplitude, v/v, corresponding to the relaxation time; t is 2_W (i) For simulating nuclear magnetic resonance T of rock core in 100% water-saturated state 2 Spectrum ith nuclear magnetic resonance T 2 Relaxation time, ms; n is the measured nuclear magnetic resonance T 2 The distribution number of the spectra is different for different nuclear magnetic resonance instruments, and the value of n is different;
for example, nuclear magnetic resonance T after simulating invasion of rock core into oil-based mud 2 The geometric mean is determined by the following formula:
in the formula, T 2lm_OB__W For simulating nuclear magnetic resonance T after core invasion of oil-based mud 2 Geometric mean, ms; amp _ OBM _ W (i) is nuclear magnetic resonance T after simulating invasion of rock core into oil-based mud 2 Spectrum ith nuclear magnetic resonance T 2 The amplitude, v/v, corresponding to the relaxation time; t is a unit of 2_OBM_W (i) For simulating nuclear magnetic resonance T after core invasion of oil-based mud 2 Spectrum ith nuclear magnetic resonance T 2 Relaxation time, ms; n is the measured nuclear magnetic resonance T 2 The distribution number of the spectra is different for different nuclear magnetic resonance instruments, and the value of n is different;
for example, NMR T of invaded oil-based mud 2 The geometric mean is determined by the following formula:
in the formula, T 2lm_OBM NMR T for invaded oil-based muds 2 Geometric mean, ms; amp _ OBM (i) is nuclear magnetic resonance T of invaded oil-based mud 2 Spectrum ith nuclear magnetic resonance T 2 The amplitude, v/v, corresponding to the relaxation time; t is 2_OBM (i) NMR T for invaded oil-based mud 2 Spectrum ith nuclear magnetic resonance T 2 Relaxation time, ms; n is the measured NMR T 2 The distribution number of the spectra is different for different nuclear magnetic resonance instruments.
Example 1
The embodiment provides a nuclear magnetic resonance T of oil-based mud invading low-porosity water layer 2 The geometric mean value correction method takes a clastic rock reservoir in western regions of China as an example to explain the technical scheme provided by the invention.
Nuclear magnetic resonance T of oil-based mud invading low-porosity water layer provided by embodiment 2 A geometric mean value correction method for nuclear magnetic resonance logging T of a part of wells in a clastic rock reservoir (marked as A reservoir) in western region of China 2 Correcting the geometric mean value, wherein the reservoirs A of the well are water layers and the invasion of the oil-based mud is the low-porosity water layer invaded by the oil-based mud of the following targets; in the method, the nuclear magnetic resonance T of the stratum suitable for a clastic rock reservoir 10 low-porosity cores taken from the west region of China is taken as an example 2 Geometric mean nuclear magnetic resonance T after invasion of oil-based mud by formation 2 Nuclear magnetic resonance T of oil-based mud with geometric mean and formation invasion 2 A calculation model of the geometric mean; specifically, the method comprises the following steps:
step one, acquiring nuclear magnetic resonance T of a target oil-based mud invaded low-porosity water layer 2 Geometric mean value:
nuclear magnetic resonance logging T for acquiring invasion of target oil-bearing-based mud into low-porosity water layer 2 A spectrum; nuclear magnetic resonance logging T based on invasion of target oil-bearing mud into low-porosity water layer 2 Spectrum, nuclear magnetic resonance T for determining invasion of target oil-based mud into low-porosity water layer 2 Geometric mean.
Step two, acquiring nuclear magnetic resonance T of the oil-based mud invaded into the low-porosity water layer by the target oil-based mud 2 Geometric mean value:
performing nuclear magnetic resonance test on the oil-based mud invaded into the low-porosity water layer by the target oil-based mud to obtain the nuclear magnetic resonance T invaded into the oil-based mud in the low-porosity water layer invaded by the target oil-based mud 2 A spectrum; nuclear magnetic resonance T based on invasion of target oil-bearing mud into low-porosity water layer 2 Spectra, nuclear magnetic resonance T of invasion of oil-based mud into low porosity water layer from target oil-bearing mud using the following formula 2 Geometric mean value:
in the formula, T 2lm_OBM NMR T for invaded oil-based mud 2 Geometric mean, ms; amp _ OBM (i) is nuclear magnetic resonance T of invaded oil-based mud 2 Spectrum ith nuclear magnetic resonance T 2 The amplitude, v/v, corresponding to the relaxation time; t is 2_OBM (i) NMR T for invaded oil-based mud 2 Spectrum ith nuclear magnetic resonance T 2 Relaxation time, ms; n is the measured NMR T 2 The number of the distribution points of the spectrum.
Step three: obtaining nuclear magnetic resonance T of formation 2 Geometric mean nuclear magnetic resonance T after invasion of oil-based mud by formation 2 Nuclear magnetic resonance T of oil-based mud with geometric mean and formation invasion 2 A calculation model of the geometric mean; as shown in fig. 3, this step includes:
3.1, obtaining simulated rock cores, carrying out nuclear magnetic resonance test on the simulated rock cores in a 100% saturated water state, and obtaining nuclear magnetic resonance T of each simulated rock core in a 100% saturated water state 2 Spectrum, and further determining the nuclear magnetic resonance T of each simulated rock core in a 100% water-saturated state 2 Geometric mean T 2lm_W ：
Selecting 10 low-porosity cores from a reservoir A (a clastic rock reservoir in western regions of China), and preparing plunger-shaped cores with the length of more than 2.5cm as simulated cores; carrying out oil washing and salt washing treatment on each simulated rock core; respectively utilizing distilled water to pressurize and soak rock of each simulated rock core subjected to oil washing and salt washing treatmentAfter the core is centered for 24 hours, each simulated rock core is in a 100% water-saturated state; respectively carrying out nuclear magnetic resonance test on each simulated rock core in a 100% saturated water state to obtain nuclear magnetic resonance T of each simulated rock core in the 100% saturated water state 2 A spectrum; based on the nuclear magnetic resonance T of each simulated rock core in the state of 100 percent of saturation water 2 Spectrum, the nuclear magnetic resonance T of each simulated rock core in the 100% water-saturated state is calculated by the following formula 2 Geometric mean T 2lm_W ：
In the formula, T 2lm_W For simulating nuclear magnetic resonance T of rock core in 100% water-saturated state 2 Geometric mean, ms; amp _ W (i) is nuclear magnetic resonance T of simulated rock core in 100% water saturation state 2 Spectrum ith nuclear magnetic resonance T 2 The amplitude, v/v, corresponding to the relaxation time; t is 2_W (i) Nuclear magnetic resonance T of core in 100% water-saturated state 2 Spectrum ith nuclear magnetic resonance T 2 Relaxation time, ms; n is the measured nuclear magnetic resonance T 2 The number of the distribution points of the spectrum;
3.2, displacing the 100% water-saturated simulated rock core by using the oil-based mud, carrying out the nuclear magnetic resonance test after the simulated rock core invades the oil-based mud, and obtaining the nuclear magnetic resonance T after each simulated rock core invades the oil-based mud 2 Spectrum, and then determining the nuclear magnetic resonance T after simulating the invasion of rock core into oil-based mud 2 Geometric mean T 2lm_OBM_W ：
Preparing oil-based mud for simulation experiment, which has the same type as that of the oil-based mud invaded by the low-porosity water layer invaded by the target oil-based mud; respectively carrying out pressurization displacement on each simulated rock core in a 100% water-saturated state for 24 hours by using oil-based mud for simulation experiments, so that each simulated rock core is immersed into the oil-based mud; respectively carrying out nuclear magnetic resonance test on each simulated rock core after the simulated rock core invades the oil-based mud to obtain the nuclear magnetic resonance T of each simulated rock core after the simulated rock core invades the oil-based mud 2 A spectrum; based on the nuclear magnetic resonance T of each simulated rock core after invading oil-based mud 2 Spectrum, calculating the simulated core invasion by using the following formulaNuclear magnetic resonance T after oil-based mud injection 2 Geometric mean T 2lm_OBM_W ：
In the formula, T 2lm_OB__W For simulating nuclear magnetic resonance T after core invasion of oil-based mud 2 Geometric mean, ms; amp _ OBM _ W (i) is nuclear magnetic resonance T after simulating invasion of rock core into oil-based mud 2 Spectrum ith nuclear magnetic resonance T 2 The amplitude, v/v, corresponding to the relaxation time; t is 2_OBM_W (i) For simulating nuclear magnetic resonance T after core invasion of oil-based mud 2 Spectrum ith nuclear magnetic resonance T 2 Relaxation time, ms; n is the measured nuclear magnetic resonance T 2 The distribution number of the spectrums;
3.3, carrying out nuclear magnetic resonance test on the oil-based mud to obtain the nuclear magnetic resonance T of the oil-based mud for simulating the invasion of the rock core 2 Spectroscopy, and thus determination of NMR T of each simulated core invaded oil-based mud 2 Geometric mean T 2lm_OBM ：
Performing nuclear magnetic resonance test on the prepared oil-based mud for the simulation experiment to obtain the nuclear magnetic resonance T of the oil-based mud for simulating the invasion of the rock core 2 Performing spectroscopy; and based on nuclear magnetic resonance T of each simulated core invaded oil-based mud 2 Spectrum, nuclear magnetic resonance T of oil-based mud invaded by each simulated core is calculated by the following formula 2 Geometric mean T 2lm_OBM ：
In the formula, T 2lm_OBM NMR T for invaded oil-based muds 2 Geometric mean, ms; amp _ OBM (i) Nuclear magnetic resonance T of invaded oil-based mud 2 Spectrum ith nuclear magnetic resonance T 2 The amplitude, v/v, corresponding to the relaxation time; t is 2_OBM (i) NMR T for invaded oil-based mud 2 Spectrum ith nuclear magnetic resonance T 2 Relaxation time, ms; n is the measured NMR T 2 The distribution number of the spectrums;
3.4 nuclear magnetic resonance T of each simulated rock core in a 100% saturated water state 2 Geometric mean T 2lm_W NMR T after invasion into oil-based mud 2 Geometric mean T 2lm_OBM_W And NMR T of invaded oil-based mud 2 Geometric mean T 2lm_OBM Determination of nuclear magnetic resonance T of formation 2 Geometric mean nuclear magnetic resonance T after invasion of oil-based mud by formation 2 Nuclear magnetic resonance T of oil-based mud with geometric mean and formation invasion 2 Calculation model of geometric mean:
based on nuclear magnetic resonance T of each simulated rock core in 100% water-saturated state 2 Geometric mean T 2lm_W NMR T after invasion of oil-based mud 2 Geometric mean T 2lm_OBM_W And NMR T of invaded oil-based mud 2 Geometric mean T 2lm_OBM Calibrating nuclear magnetic resonance T of stratum in 100% water-saturated state 2 Geometric mean (i.e. nuclear magnetic resonance of formation T) 2 Geometric mean) nuclear magnetic resonance T after invasion of oil-based mud with respect to formation 2 Nuclear magnetic resonance T of oil-based mud with geometric mean and formation invasion 2 Calculation model of geometric mean
The geometric factors x and y in the formation are obtained, thereby realizing the nuclear magnetic resonance T in the 100% water-saturated state of the formation 2 Geometric mean i-formation nuclear magnetic resonance T 2 Geometric mean nuclear magnetic resonance T after invasion of oil-based mud by formation 2 Nuclear magnetic resonance T of oil-based mud with geometric mean and formation invasion 2 Determining a calculation model of the geometric mean;
in the calculation model, T 2lm_C Nuclear magnetic resonance for formation T 2 A geometric mean value; t is 2lm_OBM NMR T for oil-based mud 2 A geometric mean value; t is a unit of 2lm_OBM_W NMR T after invasion of oil-based mud for formations 2 A geometric mean value; x and y are corrected geometric factors, and the relationship between x and y satisfies x + y =1.0;
the values of the geometric factors x and y obtained by calibration are 0.37 and 0.63, respectively.
Wherein 1 simulated core with porosity equal to 10.98% is in 100% water-saturated state, invaded by oil-based mud and nuclear magnetic resonance T of oil-based mud 2 The spectrum morphology is shown in fig. 4; as can be seen in FIG. 4, the NMR T of a 100% water-saturated low porosity core after invasion by oil-based mud 2 The spectra exhibited the following characteristics: (1) Nuclear magnetic resonance T when core is 100% saturated with water 2 Broad spectral distribution, T 2 The relaxation time is between 0.01-1400.0ms and is in a trimodal distribution, the first peak on the left reflects the surface relaxation properties of the small-pore space bound water, and the second and third peaks reflect the surface relaxation properties of the large-pore space mobile water; (2) When the low-porosity core is affected by invasion of oil-based mud, the oil-based mud cannot invade into small pore space, so that the nuclear magnetic resonance T is caused 2 The position and the form of the first peak on the left side of the spectrum are basically unchanged, and the surface relaxation property of the bound water in the small pore space is still reflected. The large pore space part is influenced by the nuclear magnetic resonance relaxation property of the emulsifier carried by the oil-based mud, so that the nuclear magnetic resonance T is caused 2 The form of the spectrum is obviously changed, and the nuclear magnetic resonance T of the rock core after the rock core is influenced by the invasion of oil-based mud 2 Narrowing of the spectral distribution, T 2 The relaxation time is between 0.01-500.0ms, and the distribution becomes bimodal, reflecting the nuclear magnetic resonance T of the rock 2 The geometric mean value becomes obviously smaller, and at the moment, if the geometric mean value is directly used for representing the rock pore structure and calculating the permeability, the calculation result is necessarily smaller than the true value.
Nuclear magnetic resonance T of 10 simulated cores in 100% water-saturated state after invasion of oil-based mud 2 The geometric mean value is shown in figure 5. The dotted line in FIG. 5 is a 45 degree diagonal line, and FIG. 5 can reflect the NMR T in two states 2 The difference between the geometric means. As can be seen in FIG. 5, when a 100% water-saturated low porosity core is affected by invasion of oil-based mud, it results in NMR T 2 Geometric means are generally small. To obtain reliable NMR T using NMR logging in invasion of oil-based mud into low porosity water layers 2 Geometric mean, need to be low hole invasion for oil-based mudNuclear magnetic resonance T of void degree water layer 2 The geometric mean is corrected.
Step four, based on nuclear magnetic resonance T of target oil-bearing mud invading low-porosity water layer 2 Nuclear magnetic resonance T of geometric mean value and target oil-base mud invaded into low-porosity water layer 2 Geometric mean, using nuclear magnetic resonance T of the formation 2 Geometric mean nuclear magnetic resonance T after invasion of oil-based mud by formation 2 Nuclear magnetic resonance T of geometric mean and invaded oil-based mud 2 A calculation model of a geometric mean value is used for determining the nuclear magnetic resonance T of the stratum with the low porosity water layer invaded by the oil-based mud under the 100% water saturation state 2 Geometric mean value, thereby completing the nuclear magnetic resonance T of the target oil-bearing mud invading the low-porosity water layer 2 And correcting the geometric mean value.
To verify the NMR T of the oil-based mud provided in this example into the low porosity water layer 2 Nuclear magnetic resonance T of formation determined in geometric mean correction method 2 Geometric mean nuclear magnetic resonance T after invasion of oil-based mud by formation 2 Nuclear magnetic resonance T of geometric mean and invaded oil-based mud 2 Accuracy of calculation model of geometric mean value by using nuclear magnetic resonance T of stratum obtained by determination 2 Geometric mean nuclear magnetic resonance T after invasion of oil-based mud by formation 2 Nuclear magnetic resonance T of geometric mean and invaded oil-based mud 2 Calculation model of geometric mean value nuclear magnetic resonance T after 10 simulated cores invade oil-based mud 2 Geometric mean T 2lm_OBM_W Correcting to obtain 10 corrected simulated rock cores 2 Geometric mean T 2lm_C 10 nuclear magnetic resonance T after correction of simulated core 2 Geometric mean T 2lm_C Nuclear magnetic resonance T measured in a 100% water-saturated state 2 Calculated T of spectrum 2 Geometric mean T 2lm_W The comparison of (a) is shown in fig. 6. As can be seen by comparing FIG. 5 with FIG. 6, NMR T obtained after correction for oil-based mud invasion 2 Nuclear magnetic resonance T in geometric mean and 100% water-saturated state 2 The data points of the geometric mean are basically distributed near the diagonal of 45 degreesThe method of the invention can be used for obtaining the reliable nuclear magnetic resonance T of the core under the 100% saturated water state after correcting the low-porosity water-containing core affected by the invasion of the oil-based mud 2 Geometric mean. Nuclear magnetic resonance T using this correction 2 The geometric mean value is used for qualitatively representing the rock pore structure and calculating the permeability, so that a reliable result can be obtained.
The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents, improvements and the like that fall within the spirit and principle of the present invention are intended to be included therein.
Claims (9)
1. Nuclear magnetic resonance T for oil-based mud invading low-porosity water layer 2 A geometric mean correction method, wherein the method comprises:
obtaining nuclear magnetic resonance T of target oil-bearing-based mud invading low-porosity water layer 2 A geometric mean value;
obtaining the nuclear magnetic resonance T of the oil-based mud invaded into the low-porosity water layer by the target oil-based mud 2 A geometric mean value;
obtaining nuclear magnetic resonance T of formation 2 Geometric mean nuclear magnetic resonance T after invasion of oil-based mud by formation 2 Nuclear magnetic resonance T of oil-based mud with geometric mean and formation invasion 2 A calculation model of the geometric mean; wherein the formation NMR T 2 Geometric mean nuclear magnetic resonance T after invasion of oil-based mud by formation 2 Nuclear magnetic resonance T of oil-based mud with geometric mean and formation invasion 2 The geometric mean calculation model is:
in the formula, T 2lm_C Nuclear magnetic resonance for formation T 2 A geometric mean value; t is 2lm_OBM NMR T for oil-based muds 2 A geometric mean value; t is 2lm_OBM_W NMR T after invasion of oil-based mud for formations 2 Geometric mean ofA value; x and y are corrected geometric factors;
nuclear magnetic resonance T based on invasion of target oil-bearing mud into low-porosity water layer 2 Nuclear magnetic resonance T of geometric mean value and target oil-base mud invaded into low-porosity water layer 2 Geometric mean, using nuclear magnetic resonance T of the formation 2 Geometric mean nuclear magnetic resonance T after invasion of oil-based mud by formation 2 Nuclear magnetic resonance T of geometric mean and invaded oil-based mud 2 A calculation model of a geometric mean value is used for determining the nuclear magnetic resonance T of a 100% water-saturated state of a stratum with a target invaded by oil-based mud into a low-porosity water layer 2 Geometric mean value, thereby completing the nuclear magnetic resonance T of the target oil-bearing mud invading the low-porosity water layer 2 And correcting the geometric mean value.
2. The method of claim 1, wherein,
obtaining nuclear magnetic resonance T of target oil-bearing-based mud invading low-porosity water layer 2 The geometric mean step includes:
nuclear magnetic resonance logging T for acquiring invasion of target oil-bearing mud into low-porosity water layer 2 A spectrum;
nuclear magnetic resonance logging T based on invasion of target oil-bearing-based mud into low-porosity water layer 2 Spectrum, nuclear magnetic resonance T for determining invasion of target oil-based mud into low-porosity water layer 2 A geometric mean value;
obtaining nuclear magnetic resonance T of invasion oil-based mud in low-porosity water layer invaded by target oil-based mud 2 The geometric mean step includes:
obtaining nuclear magnetic resonance T of invasion oil-based mud in low-porosity water layer invaded by target oil-based mud 2 A spectrum;
nuclear magnetic resonance T based on invasion of target oil-bearing mud into low-porosity water layer 2 Spectroscopy, determining the NMR T of the target oil-based mud invaded into the low porosity water layer 2 Geometric mean.
3. The method of claim 1, wherein obtaining formation nuclear magnetic resonanceVibrating T 2 Geometric mean nuclear magnetic resonance T after invasion of oil-based mud by formation 2 Nuclear magnetic resonance T of oil-based mud with geometric mean and formation invasion 2 The calculation model of the geometric mean value comprises the following steps:
obtaining nuclear magnetic resonance T of a plurality of simulated rock cores in a 100% water-saturated state 2 A geometric mean value;
obtaining nuclear magnetic resonance T of various simulated rock cores after invading oil-based mud 2 A geometric mean value;
obtaining nuclear magnetic resonance T of oil-based mud for simulating core invasion 2 A geometric mean value;
based on nuclear magnetic resonance T of each simulated rock core in 100% water-saturated state 2 Nuclear magnetic resonance T of geometric mean value after invasion of oil-based mud 2 Nuclear magnetic resonance T of geometric mean and invaded oil-based mud 2 Geometric mean value, determining the nuclear magnetic resonance T of the formation in a 100% water-saturated state 2 Geometric mean i-formation nuclear magnetic resonance T 2 Geometric mean nuclear magnetic resonance T after invasion of oil-based mud by formation 2 Nuclear magnetic resonance T of oil-based mud with geometric mean and formation invasion 2 Calculation model of geometric mean.
4. The method of claim 1, wherein the relationship between x and y in the computational model satisfies x + y =1.0.
5. The method of any one of claims 1-3, wherein nuclear magnetic resonance T 2 The geometric mean is determined by the following formula:
in the formula, T 2lm Is nuclear magnetic resonance T 2 Geometric mean, ms; amp (i) is NMR T 2 Spectrum ith nuclear magnetic resonance T 2 The amplitude, v/v, corresponding to the relaxation time; t is 2 (i) Is nuclear magnetic resonance T 2 Spectrum ith nuclear magnetic resonance T 2 Relaxation time, ms; n is measured nuclear magnetic resonanceT 2 The distribution number of the spectra is different for different nuclear magnetic resonance instruments, and the value of n is different.
6. Nuclear magnetic resonance T for oil-based mud invading low-porosity water layer 2 A geometric mean correction system, wherein the system comprises:
target layer T 2 A geometric mean acquisition module: nuclear magnetic resonance T for acquiring invasion of target oil-bearing-based mud into low-porosity water layer 2 A geometric mean value;
oil-based mud T 2 A geometric mean acquisition module: nuclear magnetic resonance T for acquiring invasion oil-based mud in low-porosity water layer invaded by oil-based mud 2 A geometric mean value;
a model acquisition module: for obtaining nuclear magnetic resonance T of earth formation 2 Geometric mean nuclear magnetic resonance T after invasion of oil-based mud by formation 2 Nuclear magnetic resonance T of oil-based mud with geometric mean and formation invasion 2 A calculation model of the geometric mean; wherein the formation NMR T 2 Geometric mean nuclear magnetic resonance T after invasion of oil-based mud by formation 2 Nuclear magnetic resonance T of oil-based mud with geometric mean and formation invasion 2 The geometric mean calculation model is:
in the formula, T 2lm_C Nuclear magnetic resonance for formation T 2 A geometric mean value; t is a unit of 2lm_OBM NMR T for oil-based mud 2 A geometric mean value; t is 2lm_OBM_W NMR T after invasion of oil-based mud for formations 2 A geometric mean value; x and y are corrected geometric factors, and the numerical values can be obtained by calibrating the nuclear magnetic resonance experiment result of the rock core;
T 2 a geometric mean correction module: nuclear magnetic resonance T for invasion of low porosity water layer based on the target oil-bearing mud 2 Nuclear magnetic resonance T of geometric mean value and target oil-base mud invaded into low-porosity water layer 2 Geometric mean using nuclear magnetic resonance T of the formation 2 Geometric mean nuclear magnetic resonance T after invasion of oil-based mud by formation 2 Nuclear magnetic resonance T of geometric mean and invaded oil-based mud 2 A calculation model of a geometric mean value is used for determining the nuclear magnetic resonance T of a 100% water-saturated state of a stratum with a target invaded by oil-based mud into a low-porosity water layer 2 Geometric mean value, thereby completing the nuclear magnetic resonance T of the target oil-bearing mud invading the low-porosity water layer 2 And correcting the geometric mean value.
7. The system of claim 6, wherein,
target layer T 2 The geometric mean acquisition module comprises:
nuclear magnetic resonance T of target zone 2 A spectrum acquisition submodule: nuclear magnetic resonance T for acquiring invasion of target oil-bearing mud into low-porosity water layer 2 A spectrum;
target layer T 2 A geometric mean determination submodule: nuclear magnetic resonance T for invasion of low porosity water layer based on target oil-bearing-based mud 2 Spectrum, nuclear magnetic resonance T for determining invasion of target oil-bearing mud into low-porosity water layer 2 A geometric mean value;
oil-based mud T 2 The geometric mean acquisition module comprises:
oil-based mud T 2 A spectrum acquisition submodule: nuclear magnetic resonance T for acquiring invasion oil-based mud in low-porosity water layer invaded by oil-based mud 2 Performing spectroscopy;
oil-based mud T 2 A geometric mean determination submodule: nuclear magnetic resonance T for invasion of oil-based mud based on invasion of target oil-bearing mud into low porosity water layer 2 Spectroscopy, determining the NMR T of the target oil-based mud invaded into the low porosity water layer 2 Geometric mean.
8. The system of claim 6, wherein the model acquisition module comprises:
the first data acquisition sub-module: used for obtaining nuclear magnetic resonance T of a plurality of simulated rock cores in a 100% water-saturated state 2 Geometric meanA value;
the second data acquisition sub-module: nuclear magnetic resonance T for obtaining simulated rock cores after invading oil-based mud 2 A geometric mean value;
a third data acquisition sub-module: nuclear magnetic resonance T for obtaining oil-based mud simulating core invasion 2 A geometric mean value;
a model determination submodule: for nuclear magnetic resonance T based on respective simulated cores in a 100% water-saturated state 2 Geometric mean, NMR T after invasion of oil-based mud 2 Nuclear magnetic resonance T of geometric mean and invaded oil-based mud 2 Geometric mean value, determining the nuclear magnetic resonance T of the formation in a 100% water-saturated state 2 Geometric mean i-formation nuclear magnetic resonance T 2 Geometric mean nuclear magnetic resonance T after invasion of oil-based mud by formation 2 Nuclear magnetic resonance T of oil-based mud with geometric mean and formation invasion 2 A computational model of the geometric mean.
9. The system of claim 6, wherein,
the relationship between x and y in the computational model satisfies x + y =1.0.
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