A new method for the production regime of gas wells based on intelligent interval control

Abstract

The present invention relates to a new method for the production regime of gas wells based on intelligent intermittent production; it solves the problems such as frequent intermittent production, excessive formation pressure loss, and decline in gas well benefits caused by unreasonable intermittent production regimes of gas wells; the technical solution is to obtain the bottom-hole flowing pressure through the binomial productivity equation, and then substitute it into the static pressure equation to obtain the theoretical wellhead pressure at the time of well opening. If the theoretical wellhead pressure can fit the actual wellhead pressure, the relevant parameters are substituted into the well test pressure build-up equation to obtain the pressure build-up curve with time as the independent variable, and at the same time, the wellhead pressure after coupling the surge pressure is converted, so as to obtain the well opening time t1, and the pressure change value △P1 = P t1 -P w , where P t1 is the pressure corresponding to the time t1 on the pressure build-up curve. When the pressure drop change value △P2 approaches △P1 after the well is opened, the well is shut in to obtain the shut-in time t2. Obtaining t1 and t2 gives the intermittent production period of the gas well.

Description

Technical Field

[0001] The present invention relates to the optimization of the gas well field drainage gas production system and belongs to the field of natural gas drainage production. Background Technique

[0002] In the middle and late stages of gas well production, due to low bottom hole pressure and gas production rate, the liquid carrying capacity of the gas well is poor, resulting in continuous increase of liquid accumulation in the wellbore, seriously affecting the normal production of the gas well. Some gas wells even have the phenomenon of liquid accumulation and production suspension. The intermittent drainage gas production system can realize well opening and closing to ensure the normal and efficient production of the gas well.

[0003] The opening degree of the intermittent cycle is basically selected from the results of the critical liquid carrying method and the field experience method, without reasonable design from the intermittent system itself, resulting in unreasonable intermittent cycle, frequent intermittent opening, excessive formation pressure loss, and decline of gas well benefits. Summary of the Invention

[0004] Objective of the present invention: In order to solve the problems of frequent intermittent opening, excessive formation pressure loss, and decline of gas well benefits caused by unreasonable intermittent system of gas wells, it is urgent to design a scheme with reasonable intermittent system and reasonable formation pressure loss.

[0005] To achieve the above objective, the present invention provides a new method for the gas well production system based on intelligent intermittent opening. This technology includes the following steps:

[0006] S100: Obtain the bottom hole flowing pressure at the time of well opening according to the binomial productivity equation, and its formula is In the formula, p R is the formation pressure (unit: MPa), p wf is the bottom hole flowing pressure at the time of well opening (unit: MPa), q g is the daily gas production (unit: 10 4 m 3 / d), T is the wellhead temperature (unit: °C), μ is the gas viscosity (unit: mPa·s), Z is the deviation coefficient (unit: dimensionless), K is the formation permeability (unit: mD), h is the reservoir thickness (unit: m), r e is the bottom hole radius (unit: m), r w is the drainage radius (unit: m), S is the skin factor (unit: dimensionless). According to the static pressure equation calculate the theoretical wellhead casing pressure during well opening production. In the formula, p c is the wellhead casing pressure (unit: MPa), γ g is the gas relative density (unit: dimensionless), H is the wellbore depth (unit: m). By fitting the actual wellhead casing pressure and observing the fitting effect, judge whether the relevant parameters are reasonable.

[0007] S200: Substitute the parameters obtained in S100 into the well test pressure build-up equation to obtain the pressure build-up curve, and its equation is where P t is the bottom-hole flowing pressure at shut-in (unit: MPa), P w is the bottom-hole flowing pressure at the last moment of well opening, which is a fixed value (unit: MPa), B is the gas volume factor, and its expression is (unit: dimensionless), C is the comprehensive elastic coefficient of formation fluid and rock pores (unit: atm -1 ), f is the effective porosity of the rock (unit: dimensionless), t is the shut-in time (unit: s), and the meanings and units of other parameters are the same as those in S100.

[0008] S300: Add up all the resistances to obtain the surge pressure (i.e., the minimum formation pressure to lift the bottom-hole liquid column to the wellhead), and its equation is P 激动压力 = [P 渗流阻力 + P 液柱压力 + P 油管阻力 + P 井口回压 , where P 渗流阻力 = f m ×(r e - r w ), where f m is the pipe flow friction coefficient (unit: dimensionless), where P 液柱阻力 = ρgH 液 , where ρ is the fluid density (unit: kg / m 3 ), where P 油管阻力 = H×e / D, where e is the absolute roughness (unit: m), D is the tubing diameter (unit: m), and P 井口回压 is generally a value given on-site.

[0009] S400: Convert the surge pressure obtained in S300 to the wellhead through the static pressure equation in S100, and at the same time couple the pressure build-up curve obtained in S200. The intersection point is the well opening time t 1 , denote the pressure change value △P 1 = P t1 - P w , where P t1 is the pressure corresponding to the time t 1 on the pressure build-up curve. After the well is opened, wait for the pressure drop change value △P 2 to approach △P 1 and then shut in the well to obtain the shut-in time t 2 , and obtain t 1 and t 2 to obtain the intermittent production cycle of the gas well. Description of the Drawings

[0010] In the drawings:

[0011] Figure 1 Method technical roadmap;

[0012] Figure 2 Flow pressure calculation and wellhead pressure fitting diagram

[0013] Figure 3 Pressure buildup curve diagram

[0014] Figure 4 Intersection point diagram of pressure buildup curve and surging pressure Specific implementation manner

[0015] The following is a detailed description of the present invention according to Figure 1 the technical roadmap and preferred embodiments in, the method comprising the following steps:

[0016] First step: Substitute the formation pressure p R , daily gas production q g , wellhead temperature T, gas viscosity μ, deviation coefficient Z, formation permeability K, reservoir thickness h, bottom hole radius r e , drainage radius r w , skin factor S into the binomial productivity equation to calculate the bottom hole flowing pressure p wf at the time of opening the well. Meanwhile, substitute the bottom hole flowing pressure p wf , wellhead temperature T, deviation coefficient Z, gas relative density γ g , wellbore depth H into the static pressure equation to calculate the theoretical wellhead casing pressure during open well production, and simultaneously fit the actual wellhead casing pressure. The results are shown in Figure 2 . If the fitting is successful, it indicates that the given parameters are reasonable, and the relevant parameters can be substituted into the next step.

[0017] Second step: Substitute the bottom hole flowing pressure P w at the last moment of opening the well, gas volume factor B, comprehensive elastic coefficient C of formation fluid and rock pores, effective porosity f of rock, shut-in time t and the relevant parameters in the first step into the well test pressure buildup equation to obtain the pressure buildup curve as Figure 3 .

[0018] Third step: Substitute the pipe flow friction coefficient f m , bottom hole radius r e , drainage radius r w into P 渗流阻力 = f m ×(r e -r w ) to obtain P 渗流阻力 . Substitute the liquid density ρ, gravitational acceleration g, liquid column height H 液 into P液柱阻力 =ρgH 液 Get P 液柱阻力 , substitute the absolute roughness e and the oil pipe diameter D into P 油管阻力 =H×e / D to get P 油管阻力 , and P 井口回压 It is usually a given value on site. By adding the above pressures, the excitation pressure is obtained, that is, P 激动压力 =[P 渗流阻力 +P 液柱压力 +P 油管阻力 +P 井口回压 ].

[0019] Step 4: Substitute the excitement pressure obtained in step 3 into Converted to the wellhead, and coupled with the pressure recovery curve obtained in the second step, the intersection point is the well opening time t 1 , record the pressure change value △P 1 =P t1 -P w , where P t1 is the pressure on the pressure recovery curve t 1 The pressure corresponding to the time, the change value of the pressure drop after the well is opened △P 2 Close to △P 1 The well is shut down at time t 2 , we get t 1 With t 2 That is, the gas well opening period is obtained.

[0020] Compared with the prior art, the present invention has the following beneficial effects: (1) The well opening and closing system derived from the mathematical model is reasonable and more practical than manual judgment; (2) In conjunction with the on-site remote control system, real-time monitoring and adjustment can be carried out to avoid loss of benefits due to waste of formation energy.

[0021] Finally, it should be noted that the above embodiments are only used to illustrate rather than limit the technical solutions of the present invention. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that the present invention can still be modified or replaced by equivalents. Any modification or partial replacement that does not depart from the spirit and scope of the present invention should be included in the scope of the claims of the present invention.

Claims

1. A new method for gas well production system based on intelligent spacing, characterized in that: The method comprises the following steps: S100: The bottom hole pressure when the well is opened is obtained according to the binomial production capacity equation, and its formula is: Where p R is the formation pressure, unit: MPa, p wf is the bottom hole flow pressure when the well is opened, unit: MPa, q g is the daily gas production, unit: 10 4 m 3 / d, T is the wellhead temperature, unit: °C, μ is the gas viscosity, unit: mPa·s, Z is the deviation coefficient, unit: dimensionless, K is the formation permeability, unit: mD, h is the reservoir thickness, unit: m, r e is the bottom radius of the well, unit: m, r w is the discharge radius, unit: m, S is the skin coefficient, unit: dimensionless, according to the static pressure equation The theoretical wellhead casing pressure when the well is started is calculated, where p c is the wellhead casing pressure, unit: MPa, γ g is the relative density of gas, unit: dimensionless, H is the wellbore depth, unit: m. By fitting the actual wellhead casing pressure, observe the fitting effect and judge whether the relevant parameters are reasonable; S200: Substitute the parameters obtained in S100 into the well test pressure recovery equation to obtain the pressure recovery curve, whose equation is: Where P t is the bottom hole flow pressure when the well is shut in, unit: MPa, P w is the bottom hole flow pressure at the last moment of well opening, which is a constant value, unit: MPa, B is the gas volume coefficient, and its expression is Unit: dimensionless, C is the combined elastic coefficient of formation fluid and rock pores, unit: atm -1 , f is the effective porosity of rock, unit: dimensionless, t is the shut-in time, unit: s, the meanings and units of other parameters are the same as S100; S300: Add up all resistances to obtain the agitation pressure, which is the minimum formation pressure that lifts the bottom hole fluid column to the wellhead. Its equation is P 激动压力 =[P 渗流阻力 +P 液柱压力 +P 油管阻力 +P 井口回压 ], where P 渗流阻力 =f m ×(r e -r w ), where f m is the friction coefficient of pipe flow, unit: dimensionless, where P 液柱阻力 =ρgH 液 , where ρ is the fluid density, unit: kg / m 3 , where P 油管阻力 =H×e / D, where e is the absolute roughness, unit: m, D is the diameter of the oil pipe, unit: m, and P 井口回压 is the given value on site; S400: The excitation pressure obtained in S300 is converted to the wellhead through the static pressure equation in S100, and the pressure recovery curve obtained in S200 is coupled at the intersection point of the well opening time t1, and the pressure change value △P1=P t1 -P w , where P t1 is the pressure corresponding to time t1 on the pressure recovery curve. After the well is opened, the well is closed when the pressure drop change value △P2 is close to △P1, and the closing time t2 is obtained. By obtaining t1 and t2, the opening cycle of the gas well is obtained.

2. According to claim 1, a new method for gas well production system based on intelligent spacing is characterized by: Source of the parameters in S100: The deviation coefficient Z is given by Calculated, where A1=0.3265, A2=-1.0700, A3=-0.5339, A4=0.01569, A5=-0.05165, A6=0.5475, A7=-0.7361, A8=0.1844, A9=0.1056, A 10 =0.6134, A 11 =0.7210, where p pr is the pressure to be compared, unit: dimensionless, T pr is the temperature to be compared, unit: dimensionless, gas viscosity μ is given by Get, where Y = 0.2 (12-X), Where M g is the mass of methane gas, unit: kg / m 3 , T e is the gas environment temperature, unit: K, γ g is the relative density of the gas, unit: dimensionless, P is the gas environment pressure, unit: MPa, R is the gas constant, unit: J / (mol·K), M air is the air mass, unit: kg / m 3 ; p R Formation pressure, K formation permeability, h reservoir thickness, r e Well bottom radius, r w is the discharge radius, S is the skin coefficient, C is the comprehensive elastic coefficient of formation fluid and rock pores, and f is the effective porosity of rock, which is obtained by the well testing software Saphir; q g The daily gas production, T the wellhead temperature, and H the wellbore depth are given by actual production data.

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