Method for designing nitrogen foam gravel packing construction parameters of strong-leakage horizontal well

Abstract

The invention belongs to the technical field of oil and gas exploitation engineering, and particularly relates to a strong-leakage horizontal well nitrogen foam gravel packing construction parameter design method which comprises the following steps: S1, obtaining a horizontal well nitrogen foam gravel packing nitrogen foam gas-water ratio Gwr and a foaming agent concentration Cf by using a reservoir leakage rate R1 and a packing safety index Fs; s2, calculating the apparent density rho f and the apparent viscosity mu f of the nitrogen foam fluid in an impact sieve annulus under the conditions of bottom hole temperature and pressure; and S3, calculating the construction displacement and the sand ratio by using the apparent density and apparent viscosity parameters of the nitrogen foam under the conditions of bottom hole temperature and pressure. The calculation and optimization process is clear, the method is clear, simple and easy to implement, an operable method is provided for rapid decision making of the loose sandstone reservoir leakage horizontal well nitrogen foam gravel packing sand prevention process, scientificity and reasonability of implementation of the loose sandstone reservoir horizontal well nitrogen foam gravel packing process are achieved, and the method is suitable for large-scale popularization and application of the loose sandstone reservoir leakage horizontal well nitrogen foam gravel packing sand prevention process. And the sand prevention and mining effects are improved.

Description

Technical Field

[0001] The invention belongs to the technical field of oil and gas production engineering, and in particular relates to a method for designing construction parameters of nitrogen foam gravel filling in a strong leakage horizontal well. Background Art

[0002] Loose sandstone reservoirs are widely distributed in my country and around the world, and have an important position in terms of reserves and production. However, due to its loose cementation, sand production is prone to occur during the mining process, so effective sand control measures need to be taken. Horizontal wells are one of the main well types for developing such reservoirs, and the common method of sand control is gravel packing technology. As the oil field enters the middle and late stages of development, the formation pressure gradually decreases, and the sand production phenomenon intensifies, resulting in a large amount of sand-carrying fluid leaking into the formation during the horizontal well gravel packing construction, further causing the sedimentary sand bed to rise. This situation can easily lead to premature sand plugging, which may eventually lead to construction failure.

[0003] Nitrogen foam sand-carrying fluid is a dispersed system formed by insoluble or slightly soluble gas dispersed in liquid or solid-liquid mixed fluid, and is a compressible non-Newtonian fluid. Low-density foam sand-carrying fluid can effectively control the liquid column and construction pressure, protect the reservoir, and minimize leakage. And as a good carrying medium, foam has excellent performance in carrying particles. At present, nitrogen foam sand-carrying horizontal well gravel packing technology has been piloted in high-loss reservoirs, and may become an important completion method for gravel packing in medium- and high-permeability reservoirs in the future.

[0004] As a technology to reduce leakage and achieve efficient filling and sand control, horizontal well nitrogen foam gravel packing still has the following key problems: 1) The existing design process is too cumbersome and complicated, and the numerical simulation optimization design is not accurate enough; there is a lack of optimization design method based on the gas-water ratio and foaming agent concentration of nitrogen foam gravel packing in horizontal wells, resulting in a lack of basis for selecting construction target wells on site; 2) There is a lack of rapid prediction method for the apparent density and viscosity of nitrogen foam in the screening annulus under bottom hole temperature and pressure conditions based on the water-gas ratio and foaming agent concentration; 3) There is a lack of a simple and fast optimization design method for the construction parameters of nitrogen foam gravel packing in horizontal wells. Summary of the invention

[0005] The current nitrogen foam gravel packing technology for horizontal wells in loose sandstone reservoirs prone to sand production lacks optimization design methods for gas-water ratio and foaming agent concentration and optimization design methods for displacement and sand ratio construction parameters.

[0006] The present invention provides a method for optimizing the nitrogen foam gas-water ratio and foaming agent concentration of nitrogen foam gravel packing in horizontal wells using simple reservoir physical property parameters and wellbore parameters; and provides a method for quickly predicting the apparent density and viscosity of nitrogen foam in the screening annulus under the conditions of bottom hole temperature and pressure; and at the same time forms a simple and fast optimization design method for the construction parameters of nitrogen foam gravel packing in horizontal wells. It provides a set of convenient and operable methods for the rapid decision-making of the process of nitrogen foam gravel packing sand prevention in loose sandstone reservoir horizontal wells, and is committed to improving the sand prevention and mining effect of leaking wells.

[0007] In order to achieve the above object, the present invention proposes a method for designing construction parameters of nitrogen foam gravel packing in a strong leakage horizontal well, comprising the following steps: S1: Use reservoir leakage rate R l and filling safety index F s Get the gas-water ratio of nitrogen foam gravel packing in horizontal wells G wr and foaming agent concentration C f ; S2: Calculate the apparent density of nitrogen foam fluid in the screen annulus at bottomhole temperature and pressure ρ f , apparent viscosity μ f ; S3: Use the apparent density and apparent viscosity parameters of nitrogen foam under bottom hole temperature and pressure conditions to calculate the construction displacement and sand ratio.

[0008] Preferably, in step S1, the horizontal well nitrogen foam gravel packing nitrogen foam gas-water ratio and foaming agent concentration optimization design method is mainly based on the basic parameters and information of reservoir geology and oil well conditions to calculate the reservoir leakage rate. R l and filling safety index F s Using these two indicators, the optimal gas-water ratio and foaming agent concentration under the conditions can be quickly determined, and the calculation method and process are simple and easy.

[0009] Preferably, in step S2, the apparent density and viscosity of the nitrogen foam in the screening annulus under the bottom hole temperature and pressure conditions are quickly calculated based on the nitrogen foam gas-water ratio and frother concentration selected in S1, so as to realize the scientific and reasonable design of efficient gravel packing of nitrogen foam horizontal wells.

[0010] Preferably, in step S3, the method for optimizing the design of construction parameters of nitrogen foam filling in horizontal wells is: using the apparent density and viscosity parameters of nitrogen foam in the screening annulus under the bottom hole temperature and pressure conditions to quickly calculate the construction displacement and sand ratio, so as to make the determination of on-site construction parameters more accurate.

[0011] Preferably, step S1 comprises the following steps: ① Calculate the reservoir leakage rate based on the basic geological parameters of the reservoir R l Reservoir leakage rate R l It is generally defined as the ratio of the volume of injected fluid to the volume of reversed fluid during on-site construction. For horizontal wells with strong leakage, the leakage during construction can be as high as 0.3-0.5. If there is no data on reservoir leakage rate on site, the simple calculation method proposed in the present invention can be used to estimate the reservoir leakage rate. R l ≤0.1, indicating no / slight leakage; 0.1< R l ≤0.2, indicating slightly aggravated leakage; 0.2< R l ≤0.35, indicating moderately aggravated omission; 0.35< R l , indicating a serious loss.

[0012] (1) in (2) In the formula, R l is the reservoir leakage rate; P f0 is the original reservoir pressure, MPa; P f is the current reservoir pressure, MPa ；P c is the construction pressure in the wellbore, MPa; h is the vertical depth of the horizontal well, m; K 0 is the original reservoir permeability, D; K is the current permeability of the reservoir (calculated by the original permeability and the volume of sand produced), D; V c is the sand production volume, obtained through on-site testing, m 3 ; V r is the volume of the formation with a radius of 3m around the production layer, m 3 ; is the formation porosity, %; V sh is the reservoir mud content, %. ρ r is the density of ordinary sand-carrying fluid, kg / m 3 ; v ris the flow rate of ordinary sand-carrying fluid, m / s; L is the length of the horizontal well section, m; Re r is the Reynolds number of the horizontal well section; d cw is the apparent diameter of the punching sleeve annulus, m; μ r It is the viscosity of ordinary sand-carrying fluid, Pa·s,g is 9.8N / kg.

[0013] ② Calculate the filling safety index F based on the basic parameters of the oil well condition s Filling safety index F s :Used to evaluate the safety level during horizontal well filling process. F s ≤0.4, indicating high risk of sand clogging; 0.4< F s ≤0.9, indicating a medium risk of sand filling blockage; 0.9< F s ≤1.2, indicating a lower risk of packing sand clogging; F s >1.2, indicating no or very low risk of sand clogging. This indicator takes into account the leakage rate R l , horizontal well inclination angle θ, loss well section length L hls , screen jacket ratio R sw And the screening ratio R cs , which are key parameters affecting whether sand plugging occurs during the horizontal well filling process.

[0014] (3) In the formula, L hls is the length of the filtration well section, m; R sw is the screen jacket ratio; R cs is the punching and screening ratio; θ is the horizontal well inclination angle, °.

[0015] ③According to the leakage rate R l and filling safety index F s Calculate the gas-water ratio G wr and foaming agent concentration C f (4) In the formula, G wr is the gas-water ratio; T is the reservoir temperature, °C.

[0016]

[0017] In the formula, C f is the concentration of foaming agent, %.

[0018] Based on the experimental simulation results, the nitrogen foam gas-water ratio and the foaming agent injection parameters are optimized and designed, and a fast calculation method for the gas-water ratio and the foaming agent concentration is formed. Based on the experimental simulation results, the present invention optimizes the nitrogen foam gas-water ratio and the foaming agent injection parameters according to the well conditions and the leakage situation. Taking the filling effect and economy into consideration, the experimental results show that for quartz sand with relatively large density, a foaming agent concentration of 1.25%-1.75% has a better effect; for ceramsite with relatively small density, a foaming agent concentration of 1%-1.5% can achieve a better effect.

[0019] According to the nitrogen foam gravel packing experiment, the optimal gas-water ratio of nitrogen foam is 1.5 (note: the gas-water ratio here refers to the ratio of nitrogen volume to water volume under the bottom hole temperature and pressure conditions). Considering the difference between the experimental and field conditions, the recommended gas-water ratio is 1.5-2.25. Based on the experimental results, the least squares method is used to fit the reservoir temperature T and the filling sand plugging risk index F. s and reservoir leakage rate R l Technical indicators, forming a quick calculation method for gas-water ratio and foaming agent concentration.

[0020] In order to facilitate on-site application and construction operation, we also provide a quick selection table for nitrogen and foaming agent injection parameters, which can quickly complete the optimization design of construction nitrogen and foaming agent injection parameters. Among them, when selecting parameters according to indicators, any two conditions in the same row can be selected, and the relationship between each indicator follows or.

[0021] Table 1 Quick selection table of nitrogen and foaming agent injection parameters

[0022] Preferably, step S2 comprises the following steps: ② Calculate nitrogen foam dryness Г (6) In the formula, is the foam dryness, %.

[0023] ③ Calculate the density of nitrogen foam fluid under bottom hole temperature and pressure conditions Nitrogen foam fluid is made of liquid and gas in a certain proportion, and its density is calculated according to the following formula: (7) In the formula, ρ f is the density of nitrogen foam fluid, kg / m 3 ; ρ l is the density of water, kg / m 3 ; ρ g is the nitrogen density at bottom hole temperature and pressure conditions, kg / m 3 , according to Figure 2 Quickly find the density of nitrogen at different temperature and pressure conditions.

[0024] ④ Calculate the rheological parameters of nitrogen foam power-law fluid under bottom hole temperature and pressure conditions According to the constitutive equation of power-law fluid and the basic equation of tubular rheology, we can get: (8) In the formula, is the shear rate, s -1 ; τ w is the shear stress on the capillary tube wall, N; K is the consistency coefficient; n is the flow index; d is the capillary tube diameter, m; L m is the length of the capillary tube, m; u is the average flow velocity in the capillary, m / s; △P is the pressure difference across the capillary, Pa.

[0025] The experiment used sodium dodecylbenzene sulfonate (SDBS), which is commonly used in oil fields, as a foaming agent. A capillary rheometer was used to conduct foam rheology experiments under different temperature, pressure and foam dryness conditions. Then, based on the relationship between flow rate and pressure drop during the experiment, the rheological parameters, flow index n and consistency coefficient K of nitrogen foam power law fluid under different temperature and pressure conditions were obtained. The calculation results obtained from the experiment are shown below.

[0026] Table 2 Calculation results of rheological parameters of power-law fluid under different foam dryness conditions

[0027] Table 3 Calculation results of rheological parameters of power-law fluid under different pressure conditions (foam mass 86%, 70℃)

[0028] Table 4 Calculation results of rheological parameters of power-law fluid under different temperature conditions (foam mass 86%, pressure 10 MPa)

[0029] By normalizing the experiment, the calculation formula of rheological parameters under different conditions is obtained by fitting: (9) Simplified, we can get (10) The above formula 10 can be used to obtain the rheological parameters of nitrogen foam power-law fluid under different temperature and pressure conditions.

[0030] ⑤ Calculate the apparent viscosity of nitrogen foam fluid in the annulus of the bottom well μ Calculate the viscosity of the nitrogen foam fluid in the bottom hole annulus (the annulus formed by the flush pipe and the casing). The shear rate of the power law fluid depends on the flow index n. The apparent diameter of the flush annulus is d. cw It means that the shear rate of the fluid flowing in the annulus of the punch sleeve can be expressed by the following formula: (11) The apparent viscosity of the nitrogen foam fluid in the punching sleeve annulus is: (12) In the formula, γ is the shear rate, s - ; K is the consistency coefficient; n is the flow index; R w is the casing radius, m; r c is the radius of the punch, m; d cw is the equivalent diameter of the punch sleeve annulus, m; u cw Average flow velocity of the annular pipe flow, m / s; t is temperature, °C; p is the formation pressure, MPa; is the foam dryness, %; μ is the apparent viscosity of the foam fluid, Pa·s.

[0031] According to the method described in steps ①-⑤ of S2 of the present invention, the apparent density and viscosity of the nitrogen foam fluid in the screening annulus under the bottom hole temperature and pressure conditions can be quickly calculated based on the gas-water ratio and the foaming agent concentration.

[0032] S3: Optimal design method for construction parameters such as sand ratio and displacement of nitrogen foam gravel packing in horizontal wells.

[0033] The invention is based on experimental and numerical simulation results, according to the nitrogen foam fluid density and the nitrogen foam apparent viscosity, and uses the least square method to fit to form a fast calculation method for the construction displacement and the construction sand ratio.

[0034] (13) In the formula, Q t Recommended bottom hole displacement for nitrogen foam gravel packing in horizontal wells, m 3 .

[0035] (14) In the formula, S g Recommended sand ratio for nitrogen foam gravel packing in horizontal wells, %.

[0036] In order to facilitate on-site application and construction operation, we also provide a quick selection table of construction displacement and construction sand ratio parameters, which can quickly complete the optimization design of construction displacement and construction sand ratio. (Note: When selecting parameters based on indicators, any condition that meets the same row can be selected, and the various indicators follow the relationship of or) Table 5 Quick selection table of injection parameters of sand-carrying fluid displacement and sand ratio

[0037] During construction, the nitrogen foam bottom hole displacement calculated according to the method of the present invention is Q t Recommended sand ratio S g Calculate the total screen annulus volume based on the nitrogen volume at bottom hole temperature and pressure conditions V g Calculating the Ground Volume of Nitrogen V l : Under the assumption of an ideal gas, the change in gas density is directly related to the ratio of its volume compression. For real gases, compression may lead to non-ideal behavior, especially under high pressure conditions. At this time, the gas may deviate from the ideal gas law and needs to introduce a compression factor Z for correction. According to the ideal gas state equation, the formation and bottom hole temperature and pressure conditions are substituted to obtain (15) In the formula, P l is the ground pressure, MPa; V l is the ground volume of nitrogen, m 3 ; T l is the ground temperature, K; Z lis the ground compression factor; P g is the bottom hole pressure, MPa; V g is the volume of nitrogen at bottom hole temperature and pressure, m 3 ; T g is the bottom hole temperature, K; Z g is the bottom hole compression factor. The compression factor can be calculated based on the critical temperature of nitrogen, 126.2 K, and the critical pressure, 3.39 MPa, by calculating the ratio of the temperature and pressure under bottom hole conditions to the critical temperature and pressure, and then looking up the compression factor based on the standard nitrogen compression factor chart; or by using Figure 1 Quickly find the compression factor Z of nitrogen under different temperature and pressure conditions and obtain the corresponding ground compression factor Z l and bottom hole compression factor Z g .

[0038] Beneficial Effects of the Invention (1) Aiming at the lack of gas-water ratio, foaming agent concentration optimization design method and construction parameter optimization design method in the current horizontal well nitrogen foam gravel packing process technology for loose sandstone reservoirs prone to sand production, the present invention proposes a set of nitrogen foam gas-water ratio and foaming agent concentration optimization design methods for horizontal well nitrogen foam gravel packing using simple reservoir physical property parameters and wellbore parameters. The index content covers the key characteristic parameters of the current oil field, takes into account comprehensively and grasps the key factors, and the corresponding calculation method and process are simple and easy to implement.

[0039] (2) The present invention proposes a method for quickly calculating the physical parameters of sand-carrying fluid based on reservoir temperature and pressure conditions, and provides a simple and fast optimization design method for nitrogen foam horizontal well gravel packing construction parameters. The calculation and optimization process is clear, the method is clear and simple, and it provides a set of operational methods for rapid decision-making on the process of nitrogen foam gravel packing sand control in loose sandstone reservoir horizontal wells, solves the scientificity and rationality of the implementation of nitrogen foam gravel packing process in loose sandstone reservoir horizontal wells, and improves the sand control and mining effects. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 is the nitrogen compressibility factor under different temperature and pressure conditions; Figure 2 is the density of nitrogen at different temperature and pressure conditions; Figure 3 is the depth trajectory of well P3; Figure 4 This is the simulation result of the filling effect of P3 well. DETAILED DESCRIPTION

[0041] Example The method for designing construction parameters of nitrogen foam gravel packing in horizontal wells with high leakage of the present invention is used to design construction parameters in the process of nitrogen foam packing in horizontal wells for the horizontal well P3 in the high leakage production block of Shengli Oilfield using the basic data shown in Table 6.

[0042] Table 6 Basic parameters of P3 well

[0043] Using the above basic data, the optimal gas-water ratio and foaming agent concentration during nitrogen foam gravel packing under the geological and well conditions of the horizontal well are calculated according to the method in step S1 of the present invention. The calculation results are shown in Table 7 below.

[0044] Table 7 Calculation results of nitrogen foam gas-water ratio and foaming agent concentration

[0045] According to the preferred gas-water ratio of 1.75 and foaming agent concentration of 1.35%, the method of step S2 of the present invention is used to calculate the apparent density and viscosity of the nitrogen foam in the screening annulus under the bottom hole temperature and pressure conditions. The calculation results are shown in the following table.

[0046] Table 8 Calculation results of nitrogen foam rheological parameters

[0047] According to the calculated nitrogen foam fluid density of 447.316 kg / m 3 , the apparent viscosity of the foam fluid is 9.357 mPa·s. The method of step S3 of the present invention is used to quickly calculate the construction displacement and sand ratio. The calculation results are shown in the following table.

[0048] Table 9 Design results of nitrogen foam filling construction parameters for horizontal wells

[0049] By calculating the total screen annulus volume, the filling sand volume is 10.221m 3 When the nitrogen foam bottom hole displacement is 0.8m 3 / min, when the sand ratio is 5.5%, the total filling time is 184.852min, and the injection volume and speed of nitrogen and water during ground construction can be calculated.

[0050] Table 10 Injection volume and speed of nitrogen and water during ground construction

[0051] Well P3 used the optimized nitrogen foam gravel packing construction parameters to carry out horizontal gravel packing on-site construction. Figure 3 is the P3 well depth trajectory, Figure 4This is the simulation result of the filling effect of P3 well. The filling rate of P3 well construction verification reached 100%, and the final filling effect was good.

Claims

1. A method for designing construction parameters of nitrogen foam gravel packing in strong leakage horizontal wells, characterized in that: The steps include: S1: Use reservoir leakage rate R l and filling safety index F s Get the gas-water ratio of nitrogen foam gravel packing in horizontal wells G wr and foaming agent concentration C f ; S2: Calculate the apparent density of nitrogen foam fluid in the screen annulus at bottomhole temperature and pressure ρ f , apparent viscosity μ f ; S3: Use the apparent density and apparent viscosity parameters of nitrogen foam under bottom hole temperature and pressure conditions to calculate the construction displacement and sand ratio.

2. The construction parameter design method according to claim 1, characterized in that: In step S1, the reservoir leakage rate R l The calculation formula is as follows: (1) in (2) In the formula, R l is the reservoir leakage rate; P f0 is the original reservoir pressure, MPa; P f is the current reservoir pressure, MPa ；P c is the construction pressure in the wellbore, MPa; h is the vertical depth of the horizontal well, m; K 0 is the original reservoir permeability, D; K is the current permeability of the reservoir, D; V c is the sand production volume, obtained through on-site testing, m 3 ; V r is the volume of the formation with a radius of 3m around the production layer, m 3 ; is the formation porosity, %; V sh is the reservoir mud content, %; ρ r is the density of ordinary sand-carrying fluid, kg / m 3 ; v r is the flow rate of ordinary sand-carrying fluid, m / s; L is the length of the horizontal well section, m; Re r is the Reynolds number of the horizontal well section; d cw is the apparent diameter of the punching sleeve annulus, m; μ r is the viscosity of ordinary sand-carrying fluid, Pa·s; g is 9.8N / kg; Filling safety index F s Calculated by the following formula: (3) In the formula, L hls is the length of the filtration well section, m; R sw is the screen jacket ratio; R cs is the punching and screening ratio; θ is the horizontal well inclination angle, °; Gas-water ratio G wr Calculated by the following formula: (4) In the formula, G wr is the gas-water ratio; T is the reservoir temperature, °C; Foaming agent concentration C f Calculated by the following formula: 。 3. The construction parameter design method according to claim 1, characterized in that: In step S1, the optimal gas-water ratio and foaming agent concentration are quickly selected according to the following conditions: (1) When 0.1 is satisfied <R l ≤0.2,0.9 <F s ≤1.2, 55℃<T≤60℃, any two of the following conditions, G wr =1.5, the filling material is quartz sand, C f 1.25%, the filling material is ceramsite, C f 1.0%; (2) When 0.2< R l ≤0.35,0.4< F s ≤0.9, 60℃<T≤65℃, any two of the following conditions, G wr =1.75, the filling material is quartz sand, C f 1.35%, the filling material is ceramsite, C f 1.25%; (3) When 0.35< R l ≤0.45,0.1 <F s ≤0.4, 65℃<T≤70℃, any two of the following conditions, G wr =2, the filling material is quartz sand, C f 1.5%, the filling material is ceramsite, C f 1.35%; (4) When 0.45< R l， F s <0.1, T>70℃, any two of the following conditions, G wr =2.25, the filling material is quartz sand, C f 1.75%, the filling material is ceramsite, C f 1.5%; in, R l is the reservoir leakage rate, F s is the filling safety index, T is the reservoir temperature, G wr is the recommended gas-water ratio, C f is the recommended bubble agent concentration.

4. The construction parameter design method according to claim 1, characterized in that: The foaming agent in S1 is sodium dodecylbenzene sulfonate.

5. The construction parameter design method according to claim 1, characterized in that: In step S2, the nitrogen foam fluid density ρ f The calculation formula is: （7） In the formula, ρ f is the density of nitrogen foam fluid, kg / m 3 ; ρ l is the density of water, kg / m 3 ; ρ g is the nitrogen density at bottom hole temperature and pressure conditions, kg / m 3 , Г is the nitrogen foam dryness, %.

6. The construction parameter design method according to claim 5, characterized in that: In step S2, the nitrogen foam dryness Γ is calculated according to the following formula: （6）。 7. The construction parameter design method according to claim 1, characterized in that: In step S2, the apparent viscosity of the nitrogen foam fluid is: （12） In the formula, γ is the shear rate, s -1 ; K is the consistency coefficient; n is the flow index; The shear rate γ Calculated by formula (11): （11） K and n Calculated by formula (10): （10） R w is the casing radius, m; r c is the radius of the punch, m; d cw is the equivalent diameter of the punch sleeve annulus, m; u cw Average flow velocity of the annular pipe flow, m / s; t is temperature, °C; p is the formation pressure, MPa; is the foam dryness, %.

8. The construction parameter design method according to claim 7, characterized in that: Formula (10) is obtained by using a capillary rheometer to conduct foam rheology experiments under different temperature, pressure and foam dryness conditions. Then, based on the relationship between flow rate and pressure drop during the experiment, the rheological parameters, flow index n and consistency coefficient K of nitrogen foam power law fluid under different temperature and pressure conditions are obtained. By normalizing the experiment, the calculation formulas for rheological parameters under different conditions are fitted and further simplified.

9. The construction parameter design method according to claim 1, characterized in that: In step S3, according to the density of the nitrogen foam fluid ρ f and nitrogen foam apparent viscosity μ , using the least squares method to fit, a fast calculation method for construction displacement and construction sand ratio is formed: (13) In the formula, Q t Recommended displacement for nitrogen foam gravel packing in horizontal wells, m 3 ; （14） In the formula, S g Recommended sand ratio for nitrogen foam gravel packing in horizontal wells, %.

10. The construction parameter design method according to claim 9, characterized in that: In step S3, Q t and S g To make a quick selection, follow these steps: (1) When ρ is satisfied f >565kg / m 3 , μ f >15mPa·s, Q t 0.5m 3 / min,S g 5%; (2) When 480<ρ f ≤565kg / m 3 , 12.5<μ f When any of the following conditions is ≤15mPa·s, Q t 0.65m 3 / min,S g 5.5%; (3) When 390<ρ f ≤480kg / m 3 , 10<μ f When any of the following conditions are met: Q t 0.8m 3 / min,S g 6.0%; (4) When 300≤ρ f ≤390kg / m 3 , 5≤μ f When any of the following conditions is ≤10mPa·s, Q t 1.25m 3 / min,S g 7.0%; (5) When ρ is satisfied f <300kg / m 3 , μ f When any of the conditions is less than 5mPa·s, Q t 1.5m 3 / min,S g 8.5%; Among them, ρ f is the density of nitrogen foam fluid, μ f is the apparent viscosity of nitrogen foam, Q t is the recommended bottom hole displacement, S g for Recommended sand ratio.

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