Novel method for gas well production system based on intelligent intermittent opening

Abstract

The invention relates to a novel gas well production system method based on intelligent intermittent opening. The problems that due to the fact that a gas well intermittent opening system is unreasonable, frequent intermittent opening is caused, stratum excessive pressure loss is caused, and gas well benefits are reduced are solved. According to the technical scheme, the flowing bottomhole pressure is obtained through a binomial productivity equation and then substituted into a static pressure equation to obtain theoretical wellhead pressure during well opening, if the theoretical wellhead pressure can be matched with actual wellhead pressure, relevant parameters are substituted into a well testing pressure recovery equation, a pressure recovery curve is obtained with time as an independent variable, meanwhile, the wellhead pressure converted by excitation pressure is coupled, and the pressure recovery curve is obtained. The pressure change value P1 = Pt1-Pw is recorded, in the formula, Pt1 is the pressure corresponding to the t1 moment 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, the well closing moment t2 is obtained, and t1 and t2 are obtained, namely the gas well interval opening period is obtained.

Description

Technical Field

[0001] The invention relates to the optimization of a gas well on-site drainage and gas production system, and belongs to the field of natural gas drainage and production. Background Art

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

[0003] The opening degree of the splicing cycle is basically selected based on the results of the critical liquid carrying method and the field experience method, and there is no reasonable design of the splicing system itself, which leads to problems such as unreasonable splicing cycle, frequent splicing, excessive formation pressure loss, and decreased gas well efficiency. Summary of the invention

[0004] Purpose of the invention: In order to solve the problems of frequent spacing, excessive formation pressure loss, and decreased gas well efficiency caused by an unreasonable gas well spacing system, it is urgently necessary to design a solution with a reasonable spacing system and reasonable formation pressure loss.

[0005] To achieve the above object, the present invention provides a new method for gas well production system based on intelligent spacing, which includes the following steps:

[0006] 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 (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), and by fitting the actual wellhead casing pressure, the fitting effect is observed to determine whether the relevant parameters are reasonable.

[0007] 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 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 (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), and the meanings and units of other parameters are the same as S100.

[0008] S300: Add up all resistances to get the exciting pressure (i.e. the minimum formation pressure that lifts the bottom hole fluid 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 diameter of the oil pipe (unit: m), and P 井口回压 Generally it is a given value on site.

[0009] 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 same time. 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. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] In the attached picture:

[0011] Figure 1 Method technology roadmap;

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

[0013] Figure 3 Pressure recovery curve

[0014] Figure 4 Intersection diagram of pressure recovery curve and agitation pressure DETAILED DESCRIPTION

[0015] According to the following Figure 1 The technical route and preferred embodiments of the present invention are described in detail, and the method comprises the following steps:

[0016] Step 1: Set the formation pressure p R , gas daily production q g , wellhead temperature T, gas viscosity μ, deviation coefficient Z, formation permeability K, reservoir thickness h, bottom hole radius r e , discharge radius r w , the skin coefficient S is substituted into the binomial capacity equation The bottom hole pressure p when the well is opened is calculated wf At the same time, the bottom hole pressure p wf , wellhead temperature T, deviation coefficient Z, gas relative density γ g , substitute the wellbore depth H into the static pressure equation The theoretical wellhead casing pressure when the well is started for production is calculated, and the actual wellhead casing pressure is fitted. The results are shown in Figure 2 If the fit is successful, it means that the given parameters are reasonable and the relevant parameters can be substituted into the next step.

[0017] Step 2: The bottom flow pressure P at the last moment of well opening w , gas volume coefficient B, comprehensive elastic coefficient C of formation fluid and rock pores, effective porosity f of rock, shut-in time t and related parameters in the first step are substituted into the well test pressure recovery equation The pressure recovery curve is Figure 3 .

[0018] Step 3: The pipe flow friction coefficient f m , bottom radius r e , discharge radius r w Substitute P 渗流阻力 =f m ×(r e -r w ) to get P 渗流阻力 , the liquid density ρ, the gravitational acceleration g, the liquid column height H 液 Substitute 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 (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), and the fitting effect is observed by fitting the actual wellhead casing pressure to determine 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 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 (unit: MPa), B is the gas volume coefficient, 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 rock (unit: dimensionless), t is the shut-in time (unit: s), and the meanings and units of other parameters are the same as S100; S300: Add up all resistances to get the exciting pressure (i.e. the minimum formation pressure that lifts the bottom hole fluid 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 diameter of the oil pipe (unit: m), and P 井口回压 Generally, it is a 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, and the intersection point is the well opening time t1, and the pressure change value ΔP1=Pt1-P w , where Pt1 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 AP2 is close to ΔP1, and the closing time t2 is obtained. The opening cycle of the gas well is obtained by obtaining t1 and t2.

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 can be obtained from 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 g Can be 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 ); and geological parameters such as p R Formation pressure, K formation permeability, h reservoir thickness, r e Well bottom radius, r w , is the drainage 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. These parameters can be obtained from the well testing software Saphir or input by empirical method; while the wellbore production part such as q g Parameters such as daily gas production, T wellhead temperature, and H wellbore depth are given by actual production data.

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