CN115407052B - Method for testing influence of wax content on phase state of high-wax-content condensate oil-gas system - Google Patents
Method for testing influence of wax content on phase state of high-wax-content condensate oil-gas system Download PDFInfo
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- 239000003921 oil Substances 0.000 claims 132
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- 239000007787 solid Substances 0.000 description 1
- 239000007790 solid phase Substances 0.000 description 1
- 238000010998 test method Methods 0.000 description 1
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Abstract
The invention discloses a method for testing the phase influence of wax content on a high-wax-content condensate gas system, which solves the technical problems that a method for testing the phase change influence of wax is not established in the prior art and research on the phase change rule of a condensate gas reservoir is not performed on the wax content. It comprises the following steps: s1, sampling and checking by a field separator; s2, determining the wax content of condensate oil, and extracting pure wax and light oil; s3, adjusting and calculating the wax content of condensate oil and calculating a sample preparation; s4, preparing formation fluid by using dead oil samples with different wax contents; s5, preparing stratum fluid by using the active oil samples with different wax contents; s6, carrying out PVT experiments on stratum fluids with different wax contents to obtain experimental data of the influence of the wax content on the phase state of the high-wax-content condensate gas system. Under the condition of not changing the gas-oil ratio and the wax component, the method is difficult to prepare the condensate gas with different wax contents, and the experimental analysis and test of the influence of the wax content on the phase state can be completed only by adopting the wax of the well to prepare the corresponding condensate gas.
Description
Technical Field
The invention relates to the field of development of high-wax-content condensate gas reservoirs, in particular to a method for testing the phase influence of wax content on a high-wax-content condensate gas system.
Background
With the expansion of the natural gas exploration field and the improvement of technology, the conventional condensate gas reservoir research can not completely meet the development and production requirements of oil and gas fields. The high-wax-content condensate gas reservoir which is different from the conventional condensate gas reservoir and is found in a certain oil field of Xinjiang Tarim is developed, the problems of serious condensate and wax precipitation are generated in the development process, the well bore is blocked due to wax deposition in the well bore, and the oil gas yield is greatly reduced, even the production is stopped. The well bore wax is seriously deposited, so that the on-site paraffin removal and prevention operation is frequent, the stable operation of production is seriously influenced, and the exploitation cost of the oil and gas reservoir is greatly increased. Meanwhile, the influence of the wax content on the dew point pressure, the reverse condensate amount and the recovery ratio of a high-wax-content condensate gas field is not clear. Therefore, in order to prevent the problem of wax deposition caused by the condensate gas reaching the wellhead from the stratum, experimental study on the influence of the wax content of the high-wax-content condensate gas reservoir on the condensate gas phase change is necessary.
Condensate reservoirs have the dual characteristics of oil reservoirs and gas reservoirs, and complicated phase change is accompanied by the whole field development process, so that great difficulty and challenges are brought to efficient development. Especially in the later stages of development, the reverse condensate damage becomes more and more severe due to the ever decreasing reservoir pressure. Wherein the reverse condensation phenomenon is mainly characterized by the condition of formation pressure When the pressure falls below the dew point pressure, reverse condensation occurs in the reservoir and builds up, causing a dramatic decrease in gas phase permeability with a concomitant significant decrease in production. However, the wax content in the gas reservoir can affect the composition of well streams, thereby affecting condensate dew point pressure, reverse condensate volume, condensate recovery rate and the like. The different components have different degrees of influence on the dew point pressure of the fluid, wherein C 3 ,C 4 ,H 2 The influence of the components such as S is obvious. And dew point pressure is an important basis for determining condensate reservoir fluid saturation and fluid characteristics. Therefore, the research of the influence of different wax contents on the condensate gas phase state has certain on-site guiding significance for formulating reasonable development modes and continuously improving the development level of the condensate gas field.
The research on the phase characteristics of the condensate gas is always the most basic and key in the related research work, and the former researches on the phase characteristics of the conventional natural gas reservoir containing wax, but aiming at the problem of the influence of the wax content in the condensate gas on the phase, the related research is imperfect, and the condensate gas reservoir is effectively developed as the development proportion of the gas reservoir is increased. Therefore, the related experimental methods are not perfect for the influence of the wax content of the high-wax-content condensate gas reservoir on the phase change, and the following problems exist:
The Ungerer et al first studied the phase change of condensate reservoirs in 1995 and used an experimental method of mixing reservoir fluids with artificial fluids in a high-pressure vessel for researching gas-liquid, gas-solid and gas-liquid-solid phase diagrams. The Nichia builds a paraffin deposition model in condensate gas through a dynamic method, and is used for comparing different points of paraffin deposition rules of condensate gas reservoirs and oil reservoirs. Leontaritis, when studying condensate production, found that paraffin deposits were present in the condensate reservoir, and he analyzed paraffin deposits in the condensate reservoir using near infrared equipment.
At present, the testing method of wax is mainly focused on wax precipitation points, wax deposition and the like, and a testing method for the influence of wax on phase change is not established yet, and no research on the influence of wax content on the phase change rule of a condensate gas reservoir is carried out. Under the condition of not changing the gas-oil ratio and the wax component, it is difficult to prepare the condensate gas with different wax content, and the corresponding condensate gas must be prepared by adopting the wax of the well, so that the experimental analysis and test of the influence of the wax content on the phase state can be completed.
In the prior art, the testing method for wax is mainly focused on wax precipitation points, wax deposition and the like, and a testing method for the influence of wax on phase change is not established yet, and no research on the influence of wax content on the phase change rule of a condensate gas reservoir is carried out.
Disclosure of Invention
The invention aims to provide a method for testing the influence of wax content on the phase state of a high-wax-content condensate gas system, which aims to solve the technical problems that a method for testing the influence of wax on the phase state change is not established in the prior art and research on the influence of the wax content on the phase state change rule of a condensate gas reservoir is not performed.
In order to achieve the above purpose, the present invention provides the following technical solutions:
the method for testing the influence of the wax content on the phase state of the high-wax-content condensate oil-gas system comprises the following steps:
s1, sampling and checking of on-site separator
Separating hydrocarbon fluid in the hydrocarbon reservoir by an on-site oil-gas separator to obtain a gas sample and an oil sample; and checking the obtained gas sample and oil sample; obtaining liquid hydrocarbon from hydrocarbon fluid in the hydrocarbon reservoir through single degassing to atmospheric condition, namely obtaining a dead oil sample, and checking the obtained dead oil sample;
s2, determining the wax content of condensate oil, and extracting pure wax and light oil
Fractionating condensate oil taken from the oil-gas separator, and separating light components from heavy components and wax components by utilizing the difference of the volatilities of all components in the oil sample; pure wax and light oil are obtained;
s3, adjusting and calculating the wax content of condensate oil and calculating a sample preparation;
S4, preparing formation fluid by using dead oil samples with different wax contents
The condensate oil sample is mixed with light oil and pure wax extracted from the same well to change the wax content of the condensate oil, and then the condensate oil sample with different wax contents is compounded with a separator gas sample under the condition of ensuring that the gas-oil ratio of the production is unchanged to obtain well streams with different wax contents;
s5, preparing stratum fluid by using the active oil samples with different wax contents;
s6, carrying out PVT experiments on stratum fluids with different wax contents to obtain experimental data of the influence of the wax content on the phase state of the high-wax-content condensate gas system.
Further, in the step S1, the gas sample inspection includes:
1) Placing the gas sample bottle filled with the gas sample in a bellows, vertically heating to the temperature of the separator, and keeping the temperature for more than 4 hours; the valve of the gas sample bottle is connected with the pressure gauge, and the reading of the pressure gauge is the gas sample pressure; the gas sample pressure and the on-site oil-gas separator pressure deviation are smaller than 5 percent, and the gas sample pressure and the on-site oil-gas separator pressure deviation are qualified;
2) The composition of the gas sample was analysed according to GB/T13610 standard.
Further, in the step S1, the oil sample inspection includes:
s11, checking oil bubble point pressure of separator
Pressurizing the separator oil sample above formation pressure at formation temperature, and shaking the oil sample sufficiently to render the oil sample single-phase; recording the pressure pump reading and the pressure value to be stabilized; after each 1-2 Mpa pressure reduction, the sample is fully shaken until the pressure is stable, and the corresponding pressure value and the pump reading are recorded; plotting the measurement result on an arithmetic coordinate, wherein a curve inflection point is the oil bubble point pressure; the separator oil bubble point pressure and the on-site separator pressure deviation are less than 5 percent, and the qualified product is obtained;
S12, single degassing experiment of separator oil sample
Pressurizing the oil sample above saturation pressure and thoroughly stirring to make it a single phase at formation temperature; transferring the single-phase stratum fluid sample into a PVT container; the pressure is kept by a metering pump, and a certain volume of stratum fluid sample is slowly and uniformly discharged, so that the oil-gas composition, the gas-oil ratio, the volume coefficient and the earth oil layer density of the separator can be measured;
s13, determining the oil gas composition of a separator oil sample by a standard SY/T5779-1995;
s14, calculating the volume coefficient and the gas-oil ratio of the separator oil
Oil tank oil: after hydrocarbon fluid in the hydrocarbon reservoir is separated by an oil-gas separator, liquid hydrocarbon which is in an equilibrium state with oil tank gas in an oil tank under the atmospheric condition is fed into the oil tank;
the step S14 includes the sub-steps of:
s141, calculating the oil volume of the oil tank:
wherein:
V ot : oil volume of oil tank, cm 3 ；
m ot Oil mass of the oil tank, g;
ρ ot : oil density of oil tank, g/cm 3 ；
S142, calculating the volume coefficient of the separator oil:
wherein:
B os the volume coefficient of the separator oil;
V os separator oil volume, cm 3 ；
S143, calculating the gas-oil ratio of the oil sample of the separator:
wherein:
GOR t separator gas-oil ratio, cm 3 /cm 3 ；
T o : standard temperature, K;
P 1 the atmospheric pressure, mpa of the day;
V 1 the volume of the evolved gas at room temperature and atmospheric pressure, cm 3 ；
P o : standard pressure, mpa;
T 1 room temperature, K.
Further, in the step S1, the dead oil sample inspection includes: dead oil density, average molecular weight and dead oil composition were determined as SH/T0604, SH/T0619 and SY/T5779-1995.
Further, the step S3 specifically includes the following substeps:
s31, adjusting and calculating the wax content of condensate oil,
determining the wax content of the light oil obtained in the step S2 to obtain a light oil component with the wax content of 0; from this, the wax content reduction formula can be obtained:
wherein:
c 1 : the concentration of the wax content of condensate oil and mol/ml;
v 1 : condensate volume, ml;
c 2 : the concentration of the wax content of the oil sample after wax reduction, and mol/ml;
v 2 : light oil volume, ml;
according to the law of conservation of mass, a wax content increase formula can be obtained:
wherein:
c 3 the concentration of the wax content of the oil sample after wax addition, and mol/ml;
c 1 : the concentration of the wax content of condensate oil and mol/ml;
v 3 : adding pure wax into the bottle, and then adding the pure wax into the bottle to obtain the inner volume of the bottle in ml;
m: extracting pure wax quality, g;
m: pure wax molar mass, g/mol;
condensate oil samples with different wax contents can be obtained through the method, and then the condensate oil samples and the separator gas sample are compounded to obtain a well flow sample;
s32, sample preparation calculation, wherein the step S32 comprises the following substeps:
s321, gas-oil ratio correction calculation;
S322, calculating sample preparation amount;
wherein, the step S321 includes the following substeps:
S3211correcting on-site production gas-oil ratio:
wherein:
GOR c : correcting gas-oil ratio, m 3 /m 3 ；
COR f : in-situ gas-oil ratio, m 3 /m 3 ；
d f : calculating the natural gas relative density used by the gas quantity on site;
Z f : calculating a natural gas deviation coefficient for the gas quantity on site;
d L : laboratory measured natural gas relative density;
d L : natural gas deviation coefficient under the condition of a separator measured in a laboratory;
s3212, calculating the gas-oil ratio of the primary separator:
wherein: GOR (gate driver) s : first-stage separator gas-oil ratio, m 3 /m 3
The step S322 includes the following sub-steps:
s3221, formulation xcm 3 Calculating the oil mass of the volume condensate gas flow sample:
wherein: v (V) op Oil consumption under sample conditions, cm 3 。
S3222, sample preparation amount calculation
(1) Gas deviation coefficient under sample matching conditions:
wherein:
Z p : coefficient of gas deviation under sample distribution conditions
P p : sample preparation pressure, mpa
V p High pressure gas volume, cm 3 ；
T p : sample preparation temperature, K;
Z 1 : the gas deviation coefficient at room temperature and atmospheric pressure is generally approximately 1;
(2) Calculating the gas distribution under the sample conditions:
wherein:
V sg : air consumption under sample preparation conditions, cm 3 ；
Z o : the gas deviation coefficient under standard conditions is generally considered to be approximately 1.
Further, in the step S4, the method specifically includes the following substeps:
S41, preparing dead oil samples with different wax contents;
s42, preparing formation fluid by using dead oil samples with different wax contents;
s43, transferring samples from PVT containers;
wherein, the step S41 comprises the following substeps:
s411, determining the wax content of dead oil according to the step S31, and then calculating according to a formula to obtain the amount of light oil required by condensate oil with different wax contents or pure wax extracted from the same well;
s412, fully mixing the condensate oil with the light oil or the extracted pure wax of the same well, heating to 50 ℃, and continuously stirring until the mixed condensate oil sample is transparent and has no sediment;
s413, determining the percentage of the wax content of the condensate oil samples with different wax contents obtained by mixing according to the step S31, and determining that the deviation of the percentage of the wax content of the condensate oil samples with different wax contents from the theoretical calculation is less than 5 percent;
the step S42 includes the sub-steps of:
s421, transferring a gas sample at the temperature of the separator into a piston type high-pressure container by adopting a gas booster pump method or a freezing method, and boosting to sample preparation pressure;
s422, cleaning the sample preparation container and connecting the sample preparation container;
s423, heating the two constant temperature baths to the sample preparation temperature, and then pumping out the sample preparation container by using a vacuum pump for 30min after the sample preparation container is pumped out to 133 pa;
s424, transferring the oil sample, calculating the required dead oil amount according to the production gas-oil ratio, and transferring the required dead oil amount into a sample preparation container by a double-pump method; calculating the required gas quantity and the required oil quantity according to the constant production gas-oil ratio in sample transfer, and then selecting dead oil with different wax contents to participate in sample transfer, so that stratum fluid with different wax contents can be obtained;
S425, transferring the gas sample, namely replacing the oil bottles in the two constant-temperature baths with gas bottles, keeping the constant production gas-oil ratio, calculating the required separator gas quantity, and transferring the required separator gas quantity into a sample preparation container by a double-pump method;
said step S43 comprises the sub-steps of:
s431, connecting PVT containers;
s432, heating the sample storage device and the PVT container to the stratum temperature, and pumping the PVT container for 30min after pumping the PVT container to 133pa by using a vacuum pump;
s433, pressurizing to the formation pressure by using a metering pump and fully stirring to make the formation pressure single-phase, slowly opening valves at the sample end of the sample storage device and the PVT container end under the condition of constant formation pressure, and transferring the required sample amount into the PVT container.
Further, in the step S5, the preparation of the formation fluid from the live oil with different wax contents includes the following substeps:
s51, preparing live oil samples with different wax contents;
s52, preparing stratum fluid by using the active oil samples with different wax contents;
s53, transferring samples from PVT containers;
wherein, the step S51 comprises the following substeps:
s511, determining the wax content of the living oil according to the step S31, and determining the mole fraction of the living oil according to the step S12, so as to calculate the oil mass and the gas quantity in 100ml of living oil samples; calculating the amount of light oil required by the active oil with different wax contents or pure wax extracted from the same well by taking the oil amount as condensate volume;
S512, reducing the wax content of the living oil, after determining the required light oil content, filling the light oil into a middle container, connecting the middle container which is transferred into the living oil in advance by using a pipeline, and pressing the required light oil content into the living oil middle container by using a metering pump;
s513, increasing the wax content of the living oil, determining the pure wax content of the living oil, filling the pure wax into an intermediate container, connecting a vacuum pump for pumping up to 133pa, connecting a pipeline, transferring the pipeline into the intermediate container of the living oil in advance, and pressing the required active oil into the intermediate container filled with the pure wax by using a metering pump;
s514, determining the percentage of the wax content of the mixed live oil samples with different wax contents according to the step S31, and determining that the deviation of the percentage of the wax content of the mixed live oil samples with different wax contents from the theoretical calculation is less than 5 percent;
the step S52 includes the sub-steps of:
s521, transferring the gas sample at the temperature of the separator into a piston type high-pressure container by adopting a gas booster pump method or a freezing method and the like, and pressurizing to the sample preparation pressure;
s522, cleaning the sample preparation container and connecting the sample preparation container;
s523, heating the two constant temperature baths to the sample preparation temperature, and then evacuating the sample preparation container by using a vacuum pump for 133pa and then evacuating for 30min;
s524, transferring the oil sample, calculating the required oil quantity according to the production gas-oil ratio, transferring the required oil quantity into a sample preparation container by a double-pump method, calculating the required gas quantity and the oil quantity according to the constant production gas-oil ratio in the transferring sample, and selecting the oil with different wax contents to participate in transferring the sample, so that stratum fluids with different wax contents can be obtained;
S525, transferring the gas sample, namely replacing the oil bottles in the two constant-temperature baths with gas bottles, keeping the constant production gas-oil ratio, calculating the required separator gas quantity, and transferring the required separator gas quantity into a sample preparation container by a double-pump method;
the step S53 includes the sub-steps of:
s531, connecting PVT containers;
s532, heating the sample storage device and the PVT container to the stratum temperature, and pumping the PVT container for 30min after pumping the PVT container to 133pa by using a vacuum pump;
s533, pressurizing to the formation pressure by using a metering pump and fully stirring to enable the formation pressure to be single-phase; and slowly opening valves at the sample end of the sample storage device and the PVT container end under the condition of constant formation pressure, and transferring the required sample amount into the PVT container.
Further, in the step S6, PVT experiments of formation fluids with different wax contents include:
s61, testing flash evaporation experiments;
s62, performing constant volume failure experiments;
s63, constant mass expansion test;
wherein said step S61 comprises the sub-steps of:
s611, matching the obtained oil gas samples with different wax contents according to the gas-oil ratio of a separator or the gas-oil ratio of on-site production, adopting a double pump method to compound well flow, and stabilizing the oil gas samples for 12 hours under the stratum temperature and the stratum pressure;
s612, opening a valve, flashing well stream to normal temperature and normal pressure, respectively measuring oil and gas volumes to obtain a gas-oil ratio, and carrying out chromatographic analysis on the oil and gas to obtain well stream components;
The step S62 includes the sub-steps of:
s621, transferring well streams with different wax contents into a PVT cylinder in a pressure maintaining manner, pumping into a pump under formation pressure to discharge 1/5 of gas, metering the discharge volume and the separated gas and liquid amounts, and taking oil and gas samples for analysis;
s622, reducing the pressure to saturation pressure, and after balancing for 2 hours, recording the reading of the pump, wherein the volume occupied by the gas in the container is equal volume;
s623, pump withdrawal, namely, step-down of 6-8 stages, wherein each stage is about 3MPa, sample shaking is carried out for 2 hours after the step-down, standing is carried out for 0.5 hour, and the pressure and the pump reading are recorded; opening a top valve for exhausting, simultaneously keeping pressure, feeding into a pump, discharging to a constant volume pump for reading, and after the exhaust is finished, recording the gas quantity, the oil quantity and the oil sampling analysis composition and the reverse condensate quantity;
said step S63 comprises the sub-steps of:
s631, transferring different well fluid pressure maintaining to the PVT cylinder, changing the pressure in the PVT cylinder in a pump withdrawal mode, observing the phase change of the well fluid, and when liquid drops or white fog appear, the pressure is the dew point pressure;
s632, after the dew point pressure is obtained, balancing for 1h, and recording the pressure and the pump reading; pumping down and reducing pressure by using a pressure drop of 2MPa, shaking the sample for 2 hours under each stage of pressure, and standing for 0.5 hour to read the pressure, the pump reading and the condensate amount; until the sample volume was expanded 3 times.
Based on the technical scheme, the embodiment of the invention at least has the following technical effects:
(1) A set of testing method of wax content to high-wax-content condensate gas phase is established, the reverse condensate liquid amount and condensate gas dew point pressure change rule of a condensate gas system under different wax content are defined, and preparation is made for further researching the relation between the wax content of the high-wax-content condensate gas reservoir and the phase change;
(2) The experimental method can quantitatively change the wax content of the condensate oil gas system under the condition of keeping the components of the well stream constant, and provides a more scientific test method for researching the influence of the wax content of the high-wax-content condensate gas reservoir on the condensate gas phase change;
(3) The experimental method not only can provide corresponding experimental test means for problems of paraffin solid phase deposition in a shaft, a gathering pipeline and a stratum in the process of exploiting an oil-gas field, but also has certain guiding significance for formulating reasonable development modes of condensate gas reservoirs and improving recovery ratio.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings that are required in the embodiments or the description of the prior art will be briefly described, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and other drawings may be obtained according to the structures shown in these drawings without inventive effort for a person skilled in the art.
FIG. 1 is a separator extraction flow diagram of an embodiment of the invention;
FIG. 2 is a formation fluid sample flowsheet of an embodiment of the present invention;
FIG. 3 is a sample flow chart of an embodiment of the present invention;
FIG. 4 is a phase diagram of a well versus different wax content;
FIG. 5 is a graph of a well's wax content versus dew point pressure;
FIG. 6 shows the reverse condensate for different wax contents for a well.
In the above figures, the reference numerals correspond to the component names as follows:
1: a gas taking valve; 2: a pressure-resistant pipeline; 3: a three-way valve; 4: a valve is arranged on the sampling bottle; 5: sampling bottle; 6: a lower valve of the sampling bottle; 7. 8: a high pressure metering pump; 9: a separator oil (or gas) sample storage bottle; 10: a sample preparation container; 11. 12: constant temperature bath; 13: a valve; 14: a sample storage device; 15: PVT containers.
Detailed Description
The following description of the embodiments of the present invention will be made clearly and fully with reference to the accompanying drawings, in which it is evident that the embodiments described are only some, but not all embodiments of the invention. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention. In addition, the technical solutions of the embodiments may be combined with each other, but it is necessary to base that the technical solutions can be realized by those skilled in the art, and when the technical solutions are contradictory or cannot be realized, the technical solutions should be considered that the combination does not exist and is not within the scope of protection claimed by the present invention.
Examples:
the invention provides a method for testing the influence of wax content on the phase state of a high-wax-content condensate gas system, which comprises the following steps:
s1, sampling and checking of on-site separator
Separating hydrocarbon fluid in the hydrocarbon reservoir by an on-site oil-gas separator to obtain a gas sample and an oil sample; and checking the obtained gas sample and oil sample; obtaining liquid hydrocarbon from hydrocarbon fluid in the hydrocarbon reservoir through single degassing to atmospheric condition, namely obtaining a dead oil sample, and checking the obtained dead oil sample;
s11, checking gas samples, wherein the checking comprises the following steps:
s111, placing a gas sample bottle filled with a gas sample in a bellows, vertically heating to the temperature of a separator, and keeping the temperature for more than 4 hours; the valve of the gas sample bottle is connected with the pressure gauge, and the reading of the pressure gauge is the gas sample pressure; the gas sample pressure and the on-site oil-gas separator pressure deviation are smaller than 5 percent, and the gas sample pressure and the on-site oil-gas separator pressure deviation are qualified;
s112, analyzing the composition of the gas sample components according to the GB/T13610 standard.
S21, checking the oil sample, wherein the checking comprises the following steps:
s211, separator bubble point pressure check
Pressurizing the separator oil sample above formation pressure at formation temperature, and shaking the oil sample sufficiently to render the oil sample single-phase; recording the pressure pump reading and the pressure value to be stabilized; after each 1-2 Mpa pressure reduction, the sample is fully shaken until the pressure is stable, and the corresponding pressure value and the pump reading are recorded; plotting the measurement result on an arithmetic coordinate, wherein a curve inflection point is the oil bubble point pressure; the separator oil bubble point pressure and the on-site separator pressure deviation are less than 5 percent, and the qualified product is obtained;
S212, single degassing experiment of separator oil sample
Pressurizing the oil sample above saturation pressure and thoroughly stirring to make it a single phase at formation temperature; transferring the single-phase stratum fluid sample into a PVT container; the pressure is kept by a metering pump, and a certain volume of stratum fluid sample is slowly and uniformly discharged, so that the oil-gas composition, the gas-oil ratio and the volume coefficient stratum oil density of the separator can be measured;
s213, determining the oil gas composition of a separator oil sample by a standard SY/T5779-1995;
s214, calculating the volume coefficient and the gas-oil ratio of the separator oil
Oil tank oil: after hydrocarbon fluid in the hydrocarbon reservoir is separated by an oil-gas separator, liquid hydrocarbon which is in an equilibrium state with oil tank gas in an oil tank under the atmospheric condition is fed into the oil tank;
s2141, oil volume of oil tank:
wherein:
V ot : oil volume of oil tank, cm 3 ；
m ot Oil mass of the oil tank, g;
ρ ot : oil density of oil tank, g/cm 3 ；
S2142, separator oil volume factor:
wherein:
B os the volume coefficient of the separator oil;
V os separator oil volume, cm 3 ；
S2143, separator oil sample gas-to-oil ratio:
wherein:
GOR t separator gas-oil ratio, cm 3 /cm 3 ；
T o : standard temperature, K;
P 1 the atmospheric pressure, mpa of the day;
V 1 the volume of the evolved gas at room temperature and atmospheric pressure, cm 3 ；
P o : standard pressure, mpa;
T 1 Room temperature, K;
s13, dead oil sample inspection
Comprising the following steps: dead oil density, average molecular weight and dead oil composition were determined as SH/T0604, SH/T0619 and SY/T5779-1995.
S2, determining the wax content of condensate oil, and extracting pure wax and light oil
Fractionating condensate oil obtained from the separator, and separating light components from heavy components and wax components by utilizing the difference of the volatilities of the components in the oil sample; pure wax and light oil are obtained;
s3, adjusting and calculating the wax content of condensate oil and calculating a sample preparation; the method specifically comprises the following substeps:
s31, adjusting and calculating the wax content of condensate
Determining the wax content of the light oil obtained in the step S2 to obtain a light oil component with the wax content of 0; from this, the wax content reduction formula can be obtained:
wherein:
c 1 : the concentration of the wax content of condensate oil and mol/ml;
v 1 : condensate volume, ml;
c 2 : the concentration of the wax content of the oil sample after wax reduction, and mol/ml;
v 2 : light oil volume, ml.
According to the law of conservation of mass, a wax content increase formula can be obtained:
wherein:
c 3 the concentration of the wax content of the oil sample after wax addition, and mol/ml;
c 1 : the concentration of the wax content of condensate oil and mol/ml;
v 3 : adding pure wax into the bottle, and then adding the pure wax into the bottle to obtain the inner volume of the bottle in ml;
m: extracting pure wax quality, g;
m: pure wax molar mass, g/mol.
Condensate oil samples with different wax contents can be obtained through the method, and then the condensate oil samples and the separator gas sample are compounded to obtain a well flow sample;
s32, sample preparation calculation
S321, gas-oil ratio correction calculation
S3211, correcting on-site production gas-oil ratio:
wherein:
GOR c : correcting gas-oil ratio, m 3 /m 3 ；
GOR f : in-situ gas-oil ratio, m 3 /m 3 ；
d f : calculating the natural gas relative density used by the gas quantity on site;
Z f : calculating a natural gas deviation coefficient for the gas quantity on site;
d L : laboratory measured natural gas relative density;
d L : natural gas deviation coefficient under the condition of a separator measured in a laboratory;
s3212, calculating the gas-oil ratio of the primary separator:
wherein:
GOR s : first-stage separator gas-oil ratio, m 3 /m 3
S322, sample preparation amount calculation
S3221, formulation xcm 3 Volume condensate gas flow sample oil mass calculation
Wherein:
V op oil consumption under sample conditions, cm 3 。
S3222, sample preparation amount calculation
(1) Gas deviation coefficient under sample matching conditions:
wherein:
Z p : coefficient of gas deviation under sample distribution conditions
P p : sample preparation pressure, mpa
V p High pressure gas volume, cm 3 ；
T p : sample preparation temperature, K;
Z 1 : the gas deviation coefficient at room temperature and atmospheric pressure (generally approximately 1).
(2) Calculating the gas distribution under the sample conditions:
wherein:
V sg : air consumption under sample preparation conditions, cm 3 ；
Z o : the gas deviation coefficient under standard conditions is generally considered to be approximately 1.
S4, preparing formation fluid by using dead oil samples with different wax contents
The condensate oil sample is mixed with light oil and pure wax extracted from the same well to change the wax content of the condensate oil, and then the condensate oil sample with different wax contents is compounded with a separator gas sample under the condition of ensuring that the gas-oil ratio of the production is unchanged to obtain well streams with different wax contents; the method specifically comprises the following substeps:
s41, preparing dead oil samples with different wax contents
S411, determining the wax content of dead oil according to the step S31, and then calculating according to a formula to obtain the amount of light oil required by condensate oil with different wax contents or pure wax extracted from the same well;
s412, fully mixing the condensate oil with the light oil or the extracted pure wax of the same well, heating to 50 ℃, and continuously stirring until the mixed condensate oil sample is transparent and has no sediment;
s413, determining the percentage of the wax content of the condensate oil samples with different wax contents obtained by mixing according to the step S31, and determining that the deviation of the percentage of the wax content of the condensate oil samples with different wax contents from the theoretical calculation is less than 5 percent;
s42, preparing formation fluid by dead oil samples with different wax contents
S421, transferring a gas sample at the temperature of the separator into a piston type high-pressure container by adopting a gas booster pump method or a freezing method, and boosting to sample preparation pressure;
S422, cleaning the sample preparation container, and connecting according to the figure 1;
s423, heating the two constant temperature baths to the sample preparation temperature, and then pumping out the sample preparation container by using a vacuum pump for 30min after the sample preparation container is pumped out to 133 pa;
s424, transferring the oil sample, calculating the required dead oil amount according to the production gas-oil ratio, and transferring the required dead oil amount into a sample preparation container by a double-pump method; calculating the required gas quantity and the required oil quantity according to the constant production gas-oil ratio in sample transfer, and then selecting dead oil with different wax contents to participate in sample transfer, so that stratum fluid with different wax contents can be obtained;
s425, transferring the gas sample, namely replacing the oil bottles in the two constant-temperature baths with gas bottles, keeping the constant production gas-oil ratio, calculating the required separator gas quantity, and transferring the required separator gas quantity into a sample preparation container by a double-pump method;
s43, PVT container sample transferring
S431, connecting PVT containers according to the figure 3;
s432, heating the sample storage device and the PVT container to the stratum temperature, and pumping the PVT container for 30min after pumping the PVT container to 133pa by using a vacuum pump;
s433, pressurizing to the formation pressure by using a metering pump and fully stirring to make the formation pressure single-phase, slowly opening valves at the sample end of the sample storage device and the PVT container end under the condition of constant formation pressure, and transferring the required sample amount into the PVT container.
S5, preparing stratum fluid by using the active oil samples with different wax contents; the method specifically comprises the following substeps:
S51, preparing active oil samples with different wax contents
S511, determining the wax content of the living oil according to the step S31, and determining the mole fraction of the living oil according to the step S12, so as to calculate the oil mass and the gas quantity in 100ml of living oil samples; calculating the amount of light oil required by the active oil with different wax contents or pure wax extracted from the same well by taking the oil amount as condensate volume;
s512, reducing the wax content of the living oil, after determining the required light oil content, filling the light oil into a middle container, connecting the middle container which is transferred into the living oil in advance by using a pipeline, and pressing the required light oil content into the living oil middle container by using a metering pump;
s513, increasing the wax content of the living oil, determining the pure wax content of the living oil, filling the pure wax into an intermediate container, connecting a vacuum pump for pumping up to 133pa, connecting a pipeline, transferring the pipeline into the intermediate container of the living oil in advance, and pressing the required active oil into the intermediate container filled with the pure wax by using a metering pump;
s514, determining the percentage of the wax content of the mixed live oil samples with different wax contents according to the step S31, and determining that the deviation of the percentage of the wax content of the mixed live oil samples with different wax contents from the theoretical calculation is less than 5 percent;
s52, preparing formation fluid by using live oil samples with different wax contents
S521, transferring the gas sample at the temperature of the separator into a piston type high-pressure container by adopting a gas booster pump method or a freezing method and the like, and pressurizing to the sample preparation pressure;
S522, cleaning the sample preparation container, and connecting according to the figure 2;
s523, heating the two constant temperature baths to the sample preparation temperature, and then evacuating the sample preparation container by using a vacuum pump for 133pa and then evacuating for 30min;
s524, transferring the oil sample, calculating the required oil quantity according to the production gas-oil ratio, transferring the required oil quantity into a sample preparation container by a double-pump method, calculating the required gas quantity and the oil quantity according to the constant production gas-oil ratio in the transferring sample, and selecting the oil with different wax contents to participate in transferring the sample, so that stratum fluids with different wax contents can be obtained;
s525, transferring the gas sample, namely replacing the oil bottles in the two constant-temperature baths with gas bottles, keeping the constant production gas-oil ratio, calculating the required separator gas quantity, and transferring the required separator gas quantity into a sample preparation container by a double-pump method;
s53, PVT container transfer sample
S531, connecting PVT containers according to the figure 3;
s532, heating the sample storage device and the PVT container to the stratum temperature, and pumping the PVT container for 30min after pumping the PVT container to 133pa by using a vacuum pump;
s533, pressurizing to the formation pressure by using a metering pump and fully stirring to enable the formation pressure to be single-phase; and slowly opening valves at the sample end of the sample storage device and the PVT container end under the condition of constant formation pressure, and transferring the required sample amount into the PVT container.
S6, carrying out PVT experiments on stratum fluids with different wax contents to obtain experimental data of the influence of the wax content on the phase state of a high-wax-content condensate gas system; the PVT experiment specifically comprises:
S61, flash evaporation experiment test
S611, matching the obtained oil gas samples with different wax contents according to the gas-oil ratio of a separator or the gas-oil ratio of on-site production, adopting a double pump method to compound well flow, and stabilizing the oil gas samples for 12 hours under the stratum temperature and the stratum pressure;
s612, opening a valve, flashing well stream to normal temperature and normal pressure, respectively measuring oil and gas volumes to obtain a gas-oil ratio, and carrying out chromatographic analysis on the oil and gas to obtain well stream components;
s62, constant volume failure experiment
S621, transferring well streams with different wax contents into a PVT cylinder in a pressure maintaining manner, pumping into a pump under formation pressure to discharge 1/5 of gas, metering the discharge volume and the separated gas and liquid amounts, and taking oil and gas samples for analysis;
s622, reducing the pressure to saturation pressure, and after balancing for 2 hours, recording the reading of the pump, wherein the volume occupied by the gas in the container is equal volume;
s623, pump withdrawal, namely, step-down of 6-8 stages, wherein each stage is about 3MPa, sample shaking is carried out for 2 hours after the step-down, standing is carried out for 0.5 hour, and the pressure and the pump reading are recorded; opening a top valve for exhausting, simultaneously keeping pressure, feeding into a pump, discharging to a constant volume pump for reading, and after the exhaust is finished, recording the gas quantity, the oil quantity and the oil sampling analysis composition and the reverse condensate quantity;
s63, constant mass expansion test
S631, transferring different well fluid pressure maintaining to the PVT cylinder, changing the pressure in the PVT cylinder in a pump withdrawal mode, observing the phase change of the well fluid, and when liquid drops or white fog appear, the pressure is the dew point pressure;
s632, after the dew point pressure is obtained, balancing for 1h, and recording the pressure and the pump reading; pumping down and reducing pressure by using a pressure drop of 2MPa, shaking the sample for 2 hours under each stage of pressure, and standing for 0.5 hour to read the pressure, the pump reading and the condensate amount; until the sample volume was expanded 3 times.
The experiment was performed by the method of example 1 on an AX well oil sample with a constant gas-oil ratio, and using condensate oil samples of different wax contents to compound with separator gas samples to obtain well stream samples of wax contents of 7.43%, 5.84%, 3.68%, 1.84%, according to the GB/T26981-2020 standard.
1. Flash evaporation experiment
And rapidly reducing the pressure of the compounded well fluid samples with different wax contents to normal pressure, measuring the gas-oil ratio, and analyzing the oil-gas components. The results are shown in table 1 below:
TABLE 1 analysis data of well stream composition for different wax contents for a well
2. Constant mass expansion experiment
The pressure in the PVT cylinder is changed in a pump withdrawal mode, so that the dew point pressure of well streams with different wax contents is observed, and high-pressure physical parameters such as deviation factors, volume coefficients, density, compression coefficients and the like of natural gas are obtained. The lower the wax content, the lower the dew point pressure was found by a large amount of experimental data as shown in fig. 4 and 5.
3. Constant volume failure experiment
The constant volume failure experiment aims to simulate parameters such as the variation of condensate saturation, the condensate extraction degree and the like in the failure development process. The pressure in the PVT cylinder is changed in a pump withdrawal mode, and gas is discharged after each stage of pressure drop, so that parameters such as condensate saturation change in the failure development process, well fluid composition in the extraction process, condensate extraction degree and the like are obtained. The higher the wax content, the higher the reverse condensate saturation was found by experimental testing as shown in fig. 6.
The foregoing has shown and described the basic principles and main features of the present invention and the advantages of the present invention. It will be understood by those skilled in the art that the present invention is not limited to the embodiments described above, and that the above embodiments and descriptions are merely illustrative of the principles of the present invention, and various changes and modifications may be made without departing from the spirit and scope of the invention, which is defined in the appended claims. The scope of the invention is defined by the appended claims and equivalents thereof.
Claims (8)
1. The method for testing the influence of the wax content on the phase state of the high-wax-content condensate oil-gas system is characterized by comprising the following steps of:
S1, sampling and checking of on-site separator
Separating hydrocarbon fluid in the hydrocarbon reservoir by an on-site oil-gas separator to obtain a gas sample and an oil sample; and checking the obtained gas sample and oil sample; obtaining liquid hydrocarbon from hydrocarbon fluid in the hydrocarbon reservoir through single degassing to atmospheric condition, namely obtaining a dead oil sample, and checking the obtained dead oil sample;
s2, determining the wax content of condensate oil, and extracting pure wax and light oil
Fractionating condensate oil taken from the oil-gas separator, and separating light components from heavy components and wax components by utilizing the difference of the volatilities of all components in the oil sample; pure wax and light oil are obtained;
s3, adjusting and calculating the wax content of condensate oil and calculating a sample preparation;
s4, preparing formation fluid by using dead oil samples with different wax contents
The condensate oil sample is mixed with light oil and pure wax extracted from the same well to change the wax content of the condensate oil, and then the condensate oil sample with different wax contents is compounded with a separator gas sample under the condition of ensuring that the gas-oil ratio of the production is unchanged to obtain well streams with different wax contents;
s5, preparing stratum fluid by using the active oil samples with different wax contents;
s6, carrying out PVT experiments on stratum fluids with different wax contents to obtain experimental data of the influence of the wax content on the phase state of the high-wax-content condensate gas system.
2. The method for testing the effect of wax content on the phase state of a high wax content condensate gas system according to claim 1, wherein in step S1, the gas sample inspection comprises:
1) Placing the gas sample bottle filled with the gas sample in a bellows, vertically heating to the temperature of the separator, and keeping the temperature for more than 4 hours; the valve of the gas sample bottle is connected with the pressure gauge, and the reading of the pressure gauge is the gas sample pressure; the gas sample pressure and the on-site oil-gas separator pressure deviation are smaller than 5 percent, and the gas sample pressure and the on-site oil-gas separator pressure deviation are qualified;
2) The composition of the gas sample was analysed according to GB/T13610 standard.
3. The method for testing the effect of wax content on the phase state of a high wax content condensate system according to claim 1, wherein in the step S1, the oil sample inspection comprises:
s11, checking oil bubble point pressure of separator
Pressurizing the separator oil sample above formation pressure at formation temperature, and shaking the oil sample sufficiently to render the oil sample single-phase; recording the pressure pump reading and the pressure value to be stabilized; after each 1-2 Mpa pressure reduction, the sample is fully shaken until the pressure is stable, and the corresponding pressure value and the pump reading are recorded; plotting the measurement result on an arithmetic coordinate, wherein a curve inflection point is the oil bubble point pressure; the separator oil bubble point pressure and the on-site separator pressure deviation are less than 5 percent, and the qualified product is obtained;
S12, single degassing experiment of separator oil sample
Pressurizing the oil sample above saturation pressure and thoroughly stirring to make it a single phase at formation temperature; transferring the single-phase stratum fluid sample into a PVT container; the pressure is kept by a metering pump, and a certain volume of stratum fluid sample is slowly and uniformly discharged, so that the oil-gas composition, the gas-oil ratio, the volume coefficient and the earth oil layer density of the separator can be measured;
s13, determining the oil gas composition of a separator oil sample by a standard SY/T5779-1995;
s14, calculating the volume coefficient and the gas-oil ratio of the separator oil
Oil tank oil: after hydrocarbon fluid in the hydrocarbon reservoir is separated by an oil-gas separator, liquid hydrocarbon which is in an equilibrium state with oil tank gas in an oil tank under the atmospheric condition is fed into the oil tank;
s141, oil volume of an oil tank:
wherein:
V ot : oil volume of oil tank, cm 3 ；
m ot : the oil quality of the oil tank, g;
ρ ot : oil density of oil tank, g/cm 3 ；
S142, separator oil volume coefficient:
wherein:
B os : the separator oil volume factor;
V os : separator oil volume, cm 3 ；
S143, separator oil sample gas-oil ratio:
wherein:
GOR t : separator gas-oil ratio, cm 3 /cm 3 ；
T o : standard temperature, K;
P 1 : atmospheric pressure, mpa on the same day;
V 1 : the volume of the evolved gas at room temperature and atmospheric pressure, cm 3 ；
P o : standard pressure, mpa;
T 1 : room temperature, K.
4. The method for testing the effect of wax content on the phase state of a high wax content condensate system according to claim 1, wherein in step S1, the dead oil sample inspection comprises: dead oil density, average molecular weight and dead oil composition were determined as SH/T0604, SH/T0619 and SY/T5779-1995.
5. A method for testing the effect of wax content on the phase state of a high wax-containing condensate gas system according to claim 3, wherein said step S3 comprises the following steps:
s31, adjusting and calculating the wax content of condensate oil,
determining the wax content of the light oil obtained in the step S2 to obtain a light oil component with the wax content of 0; from this, the wax content reduction formula can be obtained:
wherein:
c 1 : the concentration of the wax content of condensate oil and mol/ml;
v 1 : condensate volume, ml;
c 2 : the concentration of the wax content of the oil sample after wax reduction, and mol/ml;
v 2 : light oil volume, ml.
According to the law of conservation of mass, a wax content increase formula can be obtained:
wherein:
c 3 : the wax content concentration of the oil sample after wax addition, and mol/ml;
c 1 : the concentration of the wax content of condensate oil and mol/ml;
v 3 : adding pure wax into the bottle, and then adding the pure wax into the bottle to obtain the inner volume of the bottle in ml;
m: extracting pure wax quality, g;
m: pure wax molar mass, g/mol;
condensate oil samples with different wax contents can be obtained through the method, and then the condensate oil samples and the separator gas sample are compounded to obtain a well flow sample;
S32, sample preparation calculation
S321, gas-oil ratio correction calculation
S3211, correcting on-site production gas-oil ratio:
wherein:
GOR c : correcting gas-oil ratio, m 3 /m 3 ；
GOR f : in-situ gas-oil ratio, m 3 /m 3 ；
d f : calculating the natural gas relative density used by the gas quantity on site;
Z f : calculating a natural gas deviation coefficient for the gas quantity on site;
d L : laboratory measured natural gas relative density;
d L : natural gas deviation coefficient under the condition of a separator measured in a laboratory;
s3212, calculating the gas-oil ratio of the primary separator:
wherein:
GOR s : first-stage separator gas-oil ratio, m 3 /m 3
S322, sample preparation amount calculation
S3221, formulation xcm 3 Volume condensate gas flow sample oil mass calculation
Wherein:
V op : oil consumption under the condition of sample distribution bar, cm 3 ；
S3222, sample preparation amount calculation
(1) Gas deviation coefficient under sample matching conditions:
wherein:
Z p : coefficient of gas deviation under sample distribution conditions
P p : sample preparation pressure, mpa
V p : high pressure gas volume, cm 3 ；
t p : sample preparation temperature, K;
Z 1 : gas deviation coefficient at room temperature and atmospheric pressure (generally approximately 1);
(2) Calculating the gas distribution under the sample conditions:
wherein:
V sg : air consumption under sample preparation conditions, cm 3 ；
Z o : the gas deviation coefficient under standard conditions is generally considered to be approximately 1.
6. The method for testing the effect of wax content on the phase state of a high wax-containing condensate gas system according to claim 5, wherein in the step S4, the method specifically comprises the following substeps:
S41, preparing dead oil samples with different wax contents
S411, determining the wax content of dead oil according to the step S31, and then calculating according to a formula to obtain the amount of light oil required by condensate oil with different wax contents or pure wax extracted from the same well;
s412, fully mixing the condensate oil with the light oil or the extracted pure wax of the same well, heating to 50 ℃, and continuously stirring until the mixed condensate oil sample is transparent and has no sediment;
s413, determining the percentage of the wax content of the condensate oil samples with different wax contents obtained by mixing according to the step S31, and determining that the deviation of the percentage of the wax content of the condensate oil samples with different wax contents from the theoretical calculation is less than 5 percent;
s42, preparing formation fluid by dead oil samples with different wax contents
S421, transferring a gas sample at the temperature of the separator into a piston type high-pressure container by adopting a gas booster pump method or a freezing method, and boosting to sample preparation pressure;
s422, cleaning the sample preparation container and connecting the sample preparation container;
s423, heating the two constant temperature baths to the sample preparation temperature, and then pumping out the sample preparation container by using a vacuum pump for 30min after the sample preparation container is pumped out to 133 pa;
s424, transferring the oil sample, calculating the required dead oil amount according to the production gas-oil ratio, and transferring the required dead oil amount into a sample preparation container by a double-pump method; calculating the required gas quantity and the required oil quantity according to the constant production gas-oil ratio in sample transfer, and then selecting dead oil with different wax contents to participate in sample transfer, so that stratum fluid with different wax contents can be obtained;
S425, transferring the gas sample, namely replacing the oil bottles in the two constant-temperature baths with gas bottles, keeping the constant production gas-oil ratio, calculating the required separator gas quantity, and transferring the required separator gas quantity into a sample preparation container by a double-pump method;
s43, PVT container sample transferring
S431, connecting PVT containers;
s432, heating the sample storage device and the PVT container to the stratum temperature, and pumping the PVT container for 30min after pumping the PVT container to 133pa by using a vacuum pump;
s433, pressurizing to the formation pressure by using a metering pump and fully stirring to make the formation pressure single-phase, slowly opening valves at the sample end of the sample storage device and the PVT container end under the condition of constant formation pressure, and transferring the required sample amount into the PVT container.
7. The method for testing the effect of wax content on the phase state of a high wax content condensate system according to claim 5, wherein in step S5, the formulation of formation fluids from different wax content live oils comprises the sub-steps of:
s51, preparing active oil samples with different wax contents
S511, determining the wax content of the living oil according to the step S31, and determining the mole fraction of the living oil according to the step S12, so as to calculate the oil mass and the gas quantity in 100ml of living oil samples; calculating the amount of light oil required by the active oil with different wax contents or pure wax extracted from the same well by taking the oil amount as condensate volume;
S512, reducing the wax content of the living oil, after determining the required light oil content, filling the light oil into a middle container, connecting the middle container which is transferred into the living oil in advance by using a pipeline, and pressing the required light oil content into the living oil middle container by using a metering pump;
s513, increasing the wax content of the living oil, determining the pure wax content of the living oil, filling the pure wax into an intermediate container, connecting a vacuum pump for pumping up to 133pa, connecting a pipeline, transferring the pipeline into the intermediate container of the living oil in advance, and pressing the required active oil into the intermediate container filled with the pure wax by using a metering pump;
s514, determining the percentage of the wax content of the mixed live oil samples with different wax contents according to the step S31, and determining that the deviation of the percentage of the wax content of the mixed live oil samples with different wax contents from the theoretical calculation is less than 5 percent;
s52, preparing formation fluid by using live oil samples with different wax contents
S521, transferring the gas sample at the temperature of the separator into a piston type high-pressure container by adopting a gas booster pump method or a freezing method and the like, and pressurizing to the sample preparation pressure;
s522, cleaning the sample preparation container and connecting the sample preparation container;
s523, heating the two constant temperature baths to the sample preparation temperature, and then evacuating the sample preparation container by using a vacuum pump for 133pa and then evacuating for 30min;
s524, transferring the oil sample, calculating the required oil quantity according to the production gas-oil ratio, transferring the required oil quantity into a sample preparation container by a double-pump method, calculating the required gas quantity and the oil quantity according to the constant production gas-oil ratio in the transferring sample, and selecting the oil with different wax contents to participate in transferring the sample, so that stratum fluids with different wax contents can be obtained;
S525, transferring the gas sample, namely replacing the oil bottles in the two constant-temperature baths with gas bottles, keeping the constant production gas-oil ratio, calculating the required separator gas quantity, and transferring the required separator gas quantity into a sample preparation container by a double-pump method;
s53, PVT container transfer sample
S531, connecting PVT containers;
s532, heating the sample storage device and the PVT container to the stratum temperature, and pumping the PVT container for 30min after pumping the PVT container to 133pa by using a vacuum pump;
s533, pressurizing to the formation pressure by using a metering pump and fully stirring to enable the formation pressure to be single-phase; and slowly opening valves at the sample end of the sample storage device and the PVT container end under the condition of constant formation pressure, and transferring the required sample amount into the PVT container.
8. The method for testing the effect of wax content on the phase state of high wax content condensate system according to claim 1, wherein the PVT test of formation fluids with different wax contents in step S6 comprises:
s61, flash evaporation experiment test
S611, matching the obtained oil gas samples with different wax contents according to the gas-oil ratio of a separator or the gas-oil ratio of on-site production, adopting a double pump method to compound well flow, and stabilizing the oil gas samples for 12 hours under the stratum temperature and the stratum pressure;
s612, opening a valve, flashing well stream to normal temperature and normal pressure, respectively measuring oil and gas volumes to obtain a gas-oil ratio, and carrying out chromatographic analysis on the oil and gas to obtain well stream components;
S62, constant volume failure experiment
S621, transferring well streams with different wax contents into a PVT cylinder in a pressure maintaining manner, pumping into a pump under formation pressure to discharge 1/5 of gas, metering the discharge volume and the separated gas and liquid amounts, and taking oil and gas samples for analysis;
s622, reducing the pressure to saturation pressure, and after balancing for 2 hours, recording the reading of the pump, wherein the volume occupied by the gas in the container is equal volume;
s623, pump withdrawal, namely, step-down of 6-8 stages, wherein each stage is about 3MPa, sample shaking is carried out for 2 hours after the step-down, standing is carried out for 0.5 hour, and the pressure and the pump reading are recorded; opening a top valve for exhausting, simultaneously keeping pressure, feeding into a pump, discharging to a constant volume pump for reading, and after the exhaust is finished, recording the gas quantity, the oil quantity and the oil sampling analysis composition and the reverse condensate quantity;
s63, constant mass expansion test
S631, transferring different well fluid pressure maintaining to the PVT cylinder, changing the pressure in the PVT cylinder in a pump withdrawal mode, observing the phase change of the well fluid, and when liquid drops or white fog appear, the pressure is the dew point pressure;
s632, after the dew point pressure is obtained, balancing for 1h, and recording the pressure and the pump reading; pumping down and reducing pressure by using a pressure drop of 2MPa, shaking the sample for 2 hours under each stage of pressure, and standing for 0.5 hour to read the pressure, the pump reading and the condensate amount; until the sample volume was expanded 3 times.
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