Stratum thick oil high-pressure physical property sampling method under thick oil blending thin oil pilot production process

Abstract

The invention relates to the technical field of thickened oil development, in particular to a stratum thickened oil high-pressure sampling method under a thickened oil dilution blending pilot production process. Lowering the sampler to a preset sampling depth position on the whole; stopping mixing the thin oil, and metering the oil quantity produced by the oil pipe and the sleeve; after an oil pipe production gate is closed, the whole sampler is directly lifted out of a wellhead; and thin oil is positively extruded, and the reverse thin oil mixing flow of the shaft is recovered. The method comprises five steps, a qualified stratum thickened oil sample can be obtained by combining key technologies in the five steps, the serious accidents that the thickened oil returns upwards, a sampler and a weighting rod fall into a well, a steel wire is snapped and a shaft is blocked by the thickened oil due to an improper sampling method are avoided, or the result that the stratum thickened oil is not the stratum thickened oil but mixed crude oil is obtained is avoided, and the sampling efficiency is improved. And moreover, by adopting the sampling process, the probability that the whole high-pressure physical property sampler, a steel wire or a cable is in contact with high-content hydrogen sulfide is reduced, so that the corrosion and sampling cost is reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of heavy oil development, and is a method for sampling high-pressure physical properties of formation heavy oil under the process of heavy oil dilution test production. Background Art

[0002] Heavy oil in China is widely distributed, with various types, and a large proportion of reserves and production. Therefore, the exploration and development of heavy oil have always received special attention and emphasis. Among them, sampling of formation fluids in heavy oil reservoirs has always been a difficult point and has not been completely solved yet. Therefore, developing a method for sampling downhole fluids of heavy oil under corresponding processes has important economic and practical significance.

[0003] There are many types of heavy oil reservoirs. The classification of heavy oil in China is different from that of the United Nations Training Agency and Venezuela, mainly referring to its development method on the basis of viscosity classification.

[0004] From the perspective of high-pressure physical property sampling (i.e., flowing from the formation and wellbore), this research classifies heavy oil into three categories: The first category is difficult to flow in the formation. This type of heavy oil is ultra-heavy oil and part of the extra-heavy oil, and it can only flow in the wellbore after thermal recovery; The second category can flow in the formation and can flow in the lower part of the wellbore, but cannot flow in the upper part, and requires artificial assistance to lift it out of the wellhead; The third category of heavy oil can flow naturally in both the formation and the wellbore, and there is still remaining energy after reaching the wellhead. Therefore, there is no problem with downhole high-pressure physical property sampling of the third category of heavy oil, and normal downhole sampling can be carried out like light oil; The second category of heavy oil is often the focus and difficulty of high-pressure physical property sampling. This type of reservoir is mainly distributed in deep formations, and the test production methods are natural lift by diluting with light oil or screw pump lift or other lift production methods. Therefore, downhole high-pressure physical property sampling needs to be solved separately in combination with the test production process; The first category of heavy oil does not require downhole high-pressure physical property sampling and is not considered.

[0005] The reason for the difficulty in sampling heavy oil (hereinafter, heavy oil in this article specifically refers to the second category of heavy oil) is that it is difficult to lower the sampler into the wellbore, unlike light oil which is easy to lower into the well. The industry has to prepare formation fluid samples according to the gas-oil ratio. However, it is not easy to accurately determine the gas-oil ratio of heavy oil, so the samples prepared according to the gas-oil ratio have not been recognized by the industry.

[0006] The commonly used lift methods in heavy oil production are first the screw pump, followed by the conventional pump, and finally the method of assisted natural flow by diluting with light oil. Sampling heavy oil has always been a difficult problem in heavy oil exploration and development. A certain oilfield once publicly tendered for heavy oil sampling across the country; A certain bureau once carried out downhole sampling, resulting in the heavy oil flowing back, the wire breaking, the sampler and the weight rod falling into the well, and the oil well being blocked and scrapped; A certain oilfield actively carried out research, but finally there was no result. Summary of the Invention

[0007] The present invention provides a method for sampling the high-pressure physical properties of formation heavy oil under the heavy oil dilution test production process, which overcomes the deficiencies of the above-mentioned prior art. It can not only obtain qualified formation heavy oil samples, but also avoid serious accidents such as the upwelling of heavy oil caused by improper downhole sampling methods, the falling of the sampler and the weight rod into the well, the breaking of the steel wire, and the blocking of the wellbore by heavy oil.

[0008] The technical method of the present invention is summarized in the following 5 steps, namely the 5 steps of "modifying", "connecting", "measuring", "waiting", and "restoring". Combining the key technologies therein can obtain qualified formation heavy oil samples, avoid serious accidents such as the upwelling of heavy oil caused by improper sampling methods, the falling of the sampler and the weight rod into the well, the breaking of the steel wire, and the blocking of the wellbore by heavy oil, or avoid obtaining mixed crude oil instead of formation heavy oil. Moreover, through the said sampling method, the overall high-pressure physical property sampler, the cable or the steel wire have less chance of contacting high-sulfur hydrogen, thereby reducing corrosion and sampling costs.

[0009] The technical solution of the present invention is realized by the following measures: a method for sampling the high-pressure physical properties of formation heavy oil under the heavy oil dilution test production process, which is carried out during the heavy oil dilution test production process. The sampling method includes the following steps:

[0010] Step 1, change the dilution process, change the reverse dilution oil process of the wellbore to the forward dilution oil process;

[0011] Step 2, select the overall sampler and the steel wire or cable, connect the selected overall sampler with the steel wire or cable, and use the winch to lower the overall sampler to the position of the predetermined sampling depth in the wellbore;

[0012] Step 3, stop diluting the oil, open the production gate of the casing head at the wellhead, and measure the output of the mixed oil; when the measured volume of the mixed oil reaches the design value, close the production gate of the casing, and at the same time open the production gate of the tubing. When the measured volume of the mixed oil reaches the design value, close the production gate of the tubing;

[0013] Step 4, start timing after closing the production gate of the tubing. After 20 to 30 minutes, lower the sampler until it encounters two couplings, and then quickly lift it up to close the sampler, and then directly lift it out of the wellhead;

[0014] Step 5, after the sampler is lifted out of the wellbore, squeeze the dilution oil positively to make the upwelling formation heavy oil return below the screen pipe, and then restore the reverse dilution oil process of the wellbore.

[0015] The following is a further optimization or / and improvement of the above-mentioned technical solution of the invention:

[0016] The above-mentioned overall sampler includes a sampler, a weight rod and a short joint, and the sampler, the weight rod and the short joint are connected in series from bottom to top.

[0017] The selection of the above sampler assembly and the wire or cable includes the selection of the length of the sampler assembly, the diameter of the sampler, and the diameter of the wire or cable.

[0018] The selection of the above sampler assembly and the wire or cable shall be determined by the viscosity of the heavy oil at the sampling depth, as well as the sum of the frictional resistance of the sampler assembly in the heavy oil and the gravity of the wire or cable.

[0019] The viscosity of the heavy oil at the above sampling depth is calculated according to the following heavy oil fluid correlation formula:

[0020]

[0021] In the formula, μ represents the viscosity of the heavy oil, mPa·s; △p represents the pressure difference, MPa; μ0 represents the viscosity of dead oil, mPa·s; A, B, and C are all coefficients, dimensionless.

[0022] For the well section in the Lungu Oilfield area, the viscosity of the heavy oil at the sampling depth is calculated according to the following heavy oil fluid correlation formula:

[0023]

[0024] In the formula, μ represents the viscosity of the heavy oil, mPa·s; △p represents the pressure difference, MPa; μ0 represents the viscosity of dead oil, mPa·s;

[0025] This heavy oil fluid correlation formula is applicable to the sampling well section in the following parameter range:

[0026] The pressure is from 10 MPa to 61 MPa; the temperature is from 100 °C to 129.3 °C; the density of dead oil is 0.9943 g / cm 3 to 1.0211 g / cm 3 ; the gas-oil ratio is from 25.9 m 3 / m 3 to 42.46 m 3 / m 3 ; the viscosity of dead oil is from 285 mPa·s to 5907 mPa·s.

[0027] The frictional resistance of the above sampler assembly in the heavy oil is calculated according to the following formula:

[0028]

[0029] In the formula, F represents the resistance of the sampler assembly in the heavy oil, N; μ represents the viscosity of the heavy oil, mPa·s; L represents the length of the sampler assembly in the heavy oil, m; V represents the lifting speed of the sampler, m / s; m represents the ratio of the inner diameter of the tubing to the diameter of the sampler assembly, dimensionless.

[0030] The sum of the frictional resistance of the sampler assembly in viscous oil and the gravity of the wire or cable determines the diameter of the wire or cable to be used, the connection method of the sampler, the type of the sampler, and the weight of the weight rod. The frictional resistance is proportional to the viscosity of the viscous oil, the length of the sampler in the viscous oil, and the lifting speed of the wire.

[0031] The above sampler may adopt a wall scraping sampler.

[0032] Using this formula, the design of the sampler assembly and the selection of the wire or cable can be made in advance, the safety of the sampler assembly going down the well can be quantitatively estimated, and the process based on experience or on-site measurement in advance can be avoided.

[0033] The method of the present invention includes the following five steps, namely, "modifying", "connecting", "measuring", "equilibrating", and "repeating". Combining the key technologies therein can obtain qualified formation viscous oil samples, avoid serious accidents such as the viscous oil flowing back, the sampler and the weight rod falling into the well, the wire breaking, and the viscous oil blocking the wellbore due to improper sampling methods, or avoid obtaining not formation viscous oil but mixed crude oil. Moreover, by adopting the sampling process technology, the contact opportunities of the high-pressure physical property sampler assembly, the cable or the wire with high hydrogen sulfide content are reduced, thereby reducing corrosion and sampling costs. Description of the Drawings

[0034] Appendix Figure 1 It is the relationship between the frictional force received by the sampler assembly and the length, diameter of the sampler assembly, and the viscosity of the viscous oil.

[0035] Appendix Figure 2 It is the table of the fluid viscosity distribution at different depths of the wellbore of Well LG15-9 (Lungu 15-9).

[0036] Appendix Figure 3 It is the structure of the diluted oil completion string of Well Lungu 15-9.

[0037] Appendix Figure 4 It is the force condition of the sampler assembly in the viscous oil at different depth intervals of Well Lungu 15-9.

[0038] The codes in the drawings are respectively: 1 is the tubing, 2 is the casing, 3 is the tubing shoe at 5660.30 m, 4 is the screen pipe at 5457.52 m, 5 is the open hole at 5709.83 m, 6 is the return height at 3950.00 m, and 7 is the sidetrack well depth at 4800.00 m. Detailed Embodiments

[0039] The present invention is not limited by the following embodiments, and the specific implementation manners can be determined according to the technical solutions of the present invention and the actual situation.

[0040] In the present invention, the diluted oil in the diluted oil flow process (reverse diluted oil flow process, forward diluted oil flow process) is generally low-viscosity light crude oil.

[0041] Positive displacement of thin oil means positive mixing of thin oil.

[0042] The process of positive mixing of thin oil (i.e., the process of positive displacement of thin oil) refers to injecting thin oil through the tubing.

[0043] The process of reverse mixing of thin oil refers to injecting thin oil through the annulus between the tubing and the casing.

[0044] The selection of the sampler assembly and the wire or cable should be determined by the viscosity of the heavy oil at the sampling depth, as well as the sum of the frictional resistance of the sampler assembly in the heavy oil and the gravity of the wire.

[0045] Generally, the force on the wire or cable during well flushing before sampling, or on-site actual testing, is used to judge the counterweight of the sampler and the diameter of the wire or the type of cable for the next sampling. There is no prior force estimation of the wire or cable based on the viscosity of the heavy oil at the sampling location, the overall length and diameter of the sampler assembly, so the design of the selection of the sampler assembly, diameter, and wire or cable cannot be carried out. This key technology of the present invention just makes up for this deficiency. It not only eliminates the need for prior actual force testing, but more importantly, for the first time, it proposes a quantitative estimation of the tension determined by the changes in the overall length, diameter, and viscosity of the wellbore heavy oil of the wire or cable as it goes down the well, and then designs the selection of the sampler assembly and the wire or cable before sampling.

[0046] The present invention will be further described below in conjunction with embodiments:

[0047] Embodiment 1: A method for sampling the high-pressure physical properties of formation heavy oil under the heavy oil mixing with thin oil pilot test production process. This sampling method is carried out during the heavy oil mixing with thin oil pilot test production process, and the sampling method includes the following steps:

[0048] Step 1, change the mixing process of thin oil, change the reverse mixing process of thin oil in the wellbore to the positive mixing process of thin oil;

[0049] Step 2, select the sampler assembly and the wire or cable, connect the selected sampler assembly with the wire or cable, and use a winch to lower the sampler assembly to the position of the predetermined sampling depth in the wellbore;

[0050] Step 3, stop injecting thin oil, open the production gate of the casing head at the wellhead, and measure the output of the mixed oil; when the measured volume of the mixed oil reaches the design value, close the production gate of the casing, and at the same time open the production gate of the tubing. When the measured volume of the mixed oil reaches the design value, close the production gate of the tubing;

[0051] Step 4, start timing after closing the production gate of the tubing. After 20 to 30 minutes, lower the sampler until it encounters two couplings, then quickly lift it up to close the sampler, and then directly lift it out of the wellhead;

[0052] Step 5: After the sampler is lifted out of the wellbore, light oil is squeezed in the positive direction to return the upwelling formation heavy oil below the screen, and then the reverse-diluted oil flow process of the wellbore is restored.

[0053] In this set of continuous operations (sampling method), it is mainly to ensure that during the upwelling process of the heavy oil, the mixed oil in the annulus will not enter the tubing during the upwelling process of the formation heavy oil. At the same time, the tubing production gate is closed for 20 to 30 minutes, and the sampler is submerged by the upwelling heavy oil to a height of about 10 tubing lengths (the length of 1 tubing is about 10 meters). This can ensure that the wall-mounted sampler can contact 3 to 4 couplings, thereby ensuring that the sampler is in a closed state, and at the same time, the upwelling formation heavy oil is not too high to avoid major accidents such as the wellbore being blocked by heavy oil.

[0054] Therefore, it is necessary to first determine: (1) the position where the sampler is lowered in Step 1 and the temperature and pressure at this position section to calculate the heavy oil viscosity; (2) determine the sum of the frictional resistance of the sampler including the weight rod in the heavy oil and the gravity of the wire, and then determine the type selection (such as diameter) of the wire or cable; (3) accurately measure the oil production of the tubing and casing to prevent the upwelling height of the formation heavy oil from getting out of control or being too much.

[0055] So there are two key technologies involved in heavy oil sampling: one is the calculation of the heavy oil viscosity in the sampling interval; the other is the calculation of the total frictional resistance of the sampler in the heavy oil.

[0056] (1) Determination of the heavy oil viscosity in the sampling interval

[0057] The flow of reservoir fluids in the wellbore is not like the flow of fluids in the reservoir, where the temperature and pressure change gradually. The results of the high-pressure physical property analysis are the analysis results at a certain reservoir pressure and temperature, so its high-pressure physical property analysis results cannot be directly applied. Therefore, it is necessary to use the technology of multiple nonlinear regression to generate a regression empirical correlation formula, using pressure, temperature, and gas-oil ratio as the regression independent variables to express the calculation of the heavy oil viscosity as the dependent variable at the temperature and pressure experienced by the wellbore different from the reservoir pressure and temperature.

[0058] There are many regression empirical correlation formulas for estimating heavy oil viscosity, such as De Mhetto, Vasquze and Beggs, Ng and Egbogah, and Beal and Beggs—Robinson, which are all regression correlation formulas for calculating viscosity. Their common feature is that they are empirical correlation formulas based on regression processing according to reservoir types and regions. Therefore, they are only applicable to fluids in specific regions, and large errors may occur when applied in other regions.

[0059] Therefore, in addition to selecting the De Mhetto model, which is an empirical correlation formula suitable for the heavy oil in this region, this method uses the heavy oil fluid property data in this region as the regression sample, and then uses multiple nonlinear regression for processing to obtain the heavy oil fluid correlation formula as:

[0060]

[0061] Among them, the correlation coefficient of the regression equation is 0.9957%. Among the 22 groups of regression data samples, only two groups of data have a relative error of about 10%, and the relative error of the rest is less than 10%, and the average relative error is 4%.

[0062] The heavy oil fluid correlation formula is applicable to the sampling well sections in the following parameter ranges:

[0063] The pressure is from 10 MPa to 61 MPa; the temperature is from 100 °C to 129.3 °C; the dead oil density is from 0.9943 g / cm 3 to 1.0211 g / cm 3 ; the gas-oil ratio is from 25.9 m 3 / m 3 to 42.46 m 3 / m 3 ; the dead oil viscosity is from 285 mPa·s to 5907 mPa·s.

[0064] Thus far, the temperature and pressure ranges of a certain wellbore section can be determined based on the flowing temperature and flowing pressure test results of the pressure test. If it meets the above parameter ranges, then the heavy oil viscosity of the sampling well section can be calculated according to the heavy oil fluid correlation formula (1).

[0065] (2) Determination of the overall frictional resistance of the sampler

[0066] The pulling force formed by the wellbore fluid during wire or cable operations, etc. is generally judged by the well testing team through well flushing or lowering a pressure gauge, and there is no precedent for determining the pulling force in the wellbore by a calculation method. In this article, for the first time, the resistance calculation formula of the sucker rod in the heavy oil well is used to calculate the pulling force formed by the overall sampler (referring to the sampler, the weight rod, and other fittings (i.e., nipples) in series) when it is lowered into the well, so as to guide the selection and series connection method of the sampler and the weight rod, and to guide the selection of the wire or cable and its model.

[0067] The overall frictional resistance of the sampler in the heavy oil is calculated according to the following formula:

[0068]

[0069] In the formula, F represents the resistance of the overall sampler in the heavy oil, N; μ represents the heavy oil viscosity, mPa·s; L represents the length of the overall sampler in the heavy oil, m; V represents the lifting speed of the sampler, m / s; m represents the ratio of the inner diameter of the tubing to the overall diameter of the sampler, dimensionless.

[0070] After calculation (see Figure 1As can be seen (as shown), the tensile force on the steel wire during sampling or other operations in the heavy oil wellbore is mainly determined by the following factors: (1) It is determined by the length of the sampler body submerged in the heavy oil, and has little relationship with the upwelling height of the heavy oil. Therefore, the number of samplers and the number of weight rods should be controlled to ensure that the overall length of the sampler is as short as possible; (2) The position where the sampler is lowered is determined by the viscosity of the heavy oil. So, the position where the sampler is lowered should ensure that the viscosity of the heavy oil does not cause large resistance, and at the same time, it should be ensured that the sampler can move up and down freely; (3) The diameter of the sampler is also an important factor. Therefore, a sampler with the smallest possible diameter should be selected.

[0071] Example 2: A method for sampling the high-pressure physical properties of formation heavy oil under the process of heavy oil dilution-assisted production test. This method is carried out during the process of heavy oil dilution-assisted production test. The sampling method includes the following steps:

[0072] Step 1, change the dilution process from the reverse dilution oil process in the wellbore to the forward dilution oil process;

[0073] Step 2, select the sampler body and the steel wire or cable. Connect the selected sampler body with the steel wire or cable, and use a winch to lower the sampler body to the predetermined sampling depth position;

[0074] Step 3, stop diluting the oil, open the production gate of the wellhead casing, measure the output of the mixed oil in a single tank, and an antifoaming agent can be added; when the measured volume of the mixed oil reaches the designed value, close the production gate of the casing, and at the same time open the production gate of the tubing. When the measured volume of the mixed oil reaches the designed value, close the production gate of the tubing;

[0075] Step 4, start timing after closing the production gate of the tubing. After 20 to 30 minutes, lower the sampler until it encounters two couplings, and then quickly lift it up to close the sampler, and then directly lift it out of the wellhead;

[0076] Step 5, after the sampler is lifted out of the wellbore, squeeze the dilution oil to make the upwelling formation heavy oil return below the screen, and then resume the reverse dilution oil process in the wellbore.

[0077] In Example 2, the sampler body includes a sampler, a weight rod, and a short joint. The sampler, the weight rod, and the short joint are connected in series from bottom to top.

[0078] The selection of the sampler body and the steel wire or cable includes the selection of the length of the sampler body, the diameter of the sampler, and the diameter and type of the steel wire or cable.

[0079] The selection of the sampler body and the steel wire or cable should be determined by the viscosity of the heavy oil at the sampling depth, as well as the sum of the frictional resistance of the sampler body in the heavy oil and the gravity of the steel wire or cable.

[0080] The viscosity of heavy oil at the sampling depth is calculated according to the following heavy oil fluid correlation formula:

[0081]

[0082] In the formula, μ represents the viscosity of heavy oil, mPa·s; △p represents the pressure difference, MPa; μ0 represents the viscosity of dead oil, mPa·s; A, B, and C are all coefficients, dimensionless.

[0083] For the Lungu Oilfield area, the viscosity of heavy oil at the sampling depth is calculated according to the following heavy oil fluid correlation formula:

[0084]

[0085] In the formula, μ represents the viscosity of heavy oil, mPa·s; △p represents the pressure difference, MPa; μ0 represents the viscosity of dead oil, mPa·s;

[0086] This heavy oil fluid correlation formula is applicable to the sampling well section in the following parameter range:

[0087] The pressure is from 10 MPa to 61 MPa; the temperature is from 100 °C to 129.3 °C; the density of dead oil is 0.9943 g / cm 3 to 1.0211 g / cm 3 ; the gas-oil ratio is 25.9 m 3 / m 3 to 42.46 m 3 / m 3 ; the viscosity of dead oil is from 285 mPa·s to 5907 mPa·s.

[0088] The overall frictional resistance of the sampler in heavy oil is calculated according to the following formula:

[0089]

[0090] In the formula, F represents the resistance of the overall sampler in heavy oil, N; μ represents the viscosity of heavy oil, mPa·s; L represents the length of the overall sampler in heavy oil, m; V represents the lifting speed of the sampler, m / s; m represents the ratio of the inner diameter of the tubing to the overall diameter of the sampler, dimensionless.

[0091] Implementation case

[0092] Taking the downhole sampling of high-pressure physical properties of Well Lungu 15-9 as an example, it is described in detail according to the sampling method of high-pressure physical properties of formation heavy oil under the heavy oil dilution and production test process described in Example 2.

[0093] Well Lungu 15-9 produces from the Ordovician formation. The depth of the oil-bearing interval is from 5672.5 m to 5709.8 m, and the mid-depth of the oil-bearing interval is 5691.2 m. The formation pressure is 60.96 MPa, and the formation temperature is 129.3 °C. The saturation pressure of the reservoir fluid is 11.03 MPa, and the dissolved gas-oil ratio is 37.54 m 3 / m 3 , the viscosity of dead oil is 1151 mPa·s, the viscosity of degassed dead oil is 1458 mPa·s, the density of formation dead oil is 0.9523 g / cm 3 , and the density of degassed dead oil (at 20 °C) is 1.0211 g / cm 3 .

[0094] The structure of the diluted oil completion string in Well Lungu 15-9 is shown in Figure 3 . The position of the screen pipe is 5457.5 m. According to the pressure test data, the pressure gradient is 0.88 MPa / 100 m; the temperature gradient is 1.2 °C / 100 m. Also, according to the analysis of the influence of temperature on the saturation pressure in the high-pressure physical properties analysis of heavy oil, when the temperature change is small, the saturation pressure change is small. Therefore, the saturation pressure is still considered to be 11 MPa. Thus, the viscosities of heavy oil at different depths in the wellbore calculated according to the correlation formula (2) of heavy oil fluid for saturated oil viscosity (i.e., heavy oil) with pressure, temperature, and gas-oil ratio are shown in Figure 2 .

[0095] Based on the calculation of the heavy oil viscosity, the frictional resistance of the heavy oil on the overall sampler can be calculated. From the previous analysis, it can be known that the frictional resistance on the overall sampler is determined by the heavy oil viscosity, the overall length of the sampler, and the diameter of the sampler. The calculation results are shown in Figure 4 .

[0096] Therefore, a wall-mounted sampler is used in series with 2 pieces, 2 heavy rods, and other accessories (including short joints) to make the overall length of the sampler not exceed 6 m. The daily production of the oil well is calculated at 200 m³, with 0.5 m³ produced by the casing, and the formation crude oil rises approximately 50 m; at the same time, 0.5 m³ is produced by the tubing, and the formation crude oil rises approximately 100 m. The volume of the mixed oil returned from the annulus between the casing and the tubing and the tubing is designed according to this quantity. The specific sampling process is as follows:

[0097] (1) Change the reverse diluted oil flow process in the wellbore to a forward diluted oil flow process;

[0098] (2) Two wall-mounted samplers are connected in series, and at the same time, two heavy rods are equipped. Lower the wall-mounted sampler to 4800 m;

[0099] (3) Lower the wall-hanging sampler to the predetermined position, stop diluent injection, then open the casing production gate valve. After measuring and discharging 0.5 cubic meters (5 minutes), close the casing production gate valve; then open the tubing production gate valve for production. After measuring and discharging 0.5 cubic meters (about 4 minutes), close the tubing production gate valve to stop production;

[0100] (4) After waiting for 20 to 30 minutes, lower the wall-hanging sampler until it encounters two couplings, and then quickly lift it up to close the wall-hanging sampler, and then directly lift it out of the wellhead;

[0101] (5) After the wall-hanging sampler is lifted out of the wellbore, open the tubing production gate valve and squeeze in 1 cubic meter of diluent oil, then resume the reverse diluent injection process in the wellbore and resume production.

[0102] The formation heavy oil samples of Well Lungu 15-9 were successfully obtained according to the above method.

[0103] The heavy oils in the Qigu Formation of the Jurassic in the Junggar Northeast 10 Well Area and Ji 7 Well Area of Xinjiang Oilfield, the Ordovician in Tarim Oilfield, and the Ordovician in the Northwest Bureau all belong to the second type of heavy oil. Facing the second type of heavy oil under the trial production process conditions of diluent oil injection, the downhole sampling method developed (the method described in the present invention) successfully completed the high-pressure physical property sampling work of downhole heavy oil under diluent injection in the northern Tarim heavy oil, creating a precedent for successful high-pressure physical property sampling of the second type of heavy oil downhole, and providing first-hand data for the declaration of heavy oil reservoir reserves and the preparation of oilfield development plans.

[0104] The above technical features respectively constitute the embodiments of the present invention, which have strong adaptability and implementation effects. Non-essential technical features can be added or reduced according to actual needs to meet the requirements of different situations.

Claims

1. A method for sampling high-pressure physical properties of formation heavy oil under the process of heavy oil diluted production test, characterized in that, It is carried out during the process of heavy oil dilution and production test. The sampling method includes the following steps: Step 1: Change the dilution process, change the reverse dilution oil process in the wellbore to the forward dilution oil process; Step 2: Connect the overall sampler to the wire, and use the winch to lower the overall sampler to the wellbore position at the predetermined sampling depth; Step 3: Stop diluting the oil, open the casing production gate of the wellhead production device, and measure the output of the mixed oil; when the measured volume of the mixed oil reaches the design value, close the casing production gate, and at the same time open the tubing production gate. When the measured volume of the mixed oil reaches the design value, close the tubing production gate; Step 4: Start timing after closing the tubing production gate. After 20 to 30 minutes, lower the sampler of the overall sampler so that it encounters two collars, and then quickly lift it up to close the sampler, and then directly lift it out of the wellhead; Step 5: After the sampler is lifted out of the wellbore, squeeze the dilution oil to make the upwelling formation heavy oil return below the screen pipe, and then resume the reverse dilution oil process in the wellbore.

2. The method for sampling high-pressure physical properties of formation heavy oil under the heavy oil dilution test production process according to claim 1, characterized in that, The overall sampler includes a sampler, a weight rod and a nipple, and the sampler, the weight rod and the nipple are connected in series from bottom to top.

3. The sampling method for high-pressure physical properties of formation heavy oil under the heavy oil dilution test production process according to claim 1 or 2, characterized in that, The selection of the overall sampler and the wire or cable includes the selection of the length of the overall sampler, the diameter of the sampler and the diameter of the wire.

4. The method for sampling high-pressure physical properties of formation heavy oil under the heavy oil dilution test production process according to claim 3, characterized in that The selection of the overall sampler and the wire or cable is determined by the viscosity of the heavy oil at the sampling depth, and the sum of the frictional resistance of the overall sampler in the heavy oil and the gravity of the wire.

5. The method for sampling the high-pressure physical properties of formation heavy oil under the heavy oil dilution test production process according to claim 4, characterized in that, The viscosity of the heavy oil at the sampling depth is calculated according to the following heavy oil fluid correlation formula: In the formula, μ represents the viscosity of the heavy oil, mPa·s; △p represents the pressure difference, MPa; μ0 represents the viscosity of dead oil, mPa·s; A, B, and C are all coefficients, dimensionless.

6. The method for sampling high-pressure physical properties of formation heavy oil under the heavy oil dilution test production process according to claim 5, characterized in that, For the heavy oil viscosity in the Lungu Oilfield area, it is calculated according to the following heavy oil fluid correlation formula: In the formula, μ represents the viscosity of the heavy oil, mPa·s; △p represents the pressure difference, MPa; μ0 represents the viscosity of dead oil, mPa·s; This heavy oil fluid correlation formula is applicable to the sampling well section in the following parameter range: The pressure ranges from 10 MPa to 61 MPa; the temperature ranges from 100 °C to 129.3 °C; the dead oil density ranges from 0.9943 g / cm 3 to 1.0211 g / cm 3 ; the gas-oil ratio ranges from 25.9 m 3 / m 3 to 42.46 m 3 / m 3 ; the dead oil viscosity ranges from 285 mPa·s to 5907 mPa·s.

7. The method for sampling high-pressure physical properties of formation heavy oil under the heavy oil dilution test production process according to claim 4 or 5 or 6, characterized in that, The frictional resistance of the overall sampler in the heavy oil is calculated according to the following formula: In the formula, F represents the resistance of the overall sampler in the heavy oil, N; μ represents the viscosity of the heavy oil, mPa·s; L represents the length of the overall sampler in the heavy oil, m; V represents the lifting speed of the sampler, m / s; m represents the ratio of the inner diameter of the tubing to the diameter of the overall sampler, dimensionless.

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