Intermittent flow medium distribution inversion and water holding rate calculation method and system for horizontal gas well

Abstract

The invention provides a horizontal gas well intermittent flow medium distribution inversion and water holdup calculation method and system. The system comprises an interface interpolation extension imaging algorithm and a circle-ellipse water holdup calculation model. A gas-liquid mixing area is accurately identified by combining the position of a circumferential probe of an array holdup meter and a water holdup response value, the position of the lowest point of a gas-liquid interface is determined by utilizing the chord length corresponding to the wetted wall perimeter and the wetted wall fraction, an arc-shaped threshold value and a median interface are drawn, and water holdup assignment is performed on a grid through interpolation; an ellipse intersecting with the shaft at the three points is constructed through the positions of the equivalent probes of the threshold values and the median values of the mixing areas on the two sides of the shaft and the lowest point position of the gas-liquid interface, gas-liquid two-phase distribution is divided through the ellipse, and then the average water holding rate of the section of the shaft is obtained. According to the method, high-precision recognition and inversion of the gas-liquid interface of the complex flow pattern of the horizontal gas well are achieved, the limitation of quantitative calculation of the water holding rate under the complex flow pattern condition of the horizontal well section in a traditional method is overcome, and the calculation precision of the water holding rate of the complex flow pattern of the horizontal well is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of inversion of intermittent flow medium distribution and calculation of water holdup in horizontal gas wells, and particularly relates to a method and system for inverting intermittent flow medium distribution and calculating water holdup in horizontal gas wells. Background Art

[0002] The dynamic information of production and development in the horizontal well section is the key basis for guiding the optimization and adjustment of oil and gas field development plans. The imaging processing of array holdup data can not only visually display the production dynamics of oil and gas wells, but also be used for the fine interpretation of the production profile. The fluid holdup is a key parameter for the inversion of the flow profile in horizontal wells and the quantitative evaluation of the production dynamics of individual layers, and plays an important supporting role in accurately locating the water-producing layer in the horizontal well section, guiding the implementation of processes for improving the recovery rate of gas reservoirs, and clarifying the primary and secondary production layer positions in multiple production layers.

[0003] Currently, the more commonly used flow imaging logging instruments mainly adopt the form of array probe distribution. For example, the array capacitance water holdup meter CAT, array resistance water holdup meter RAT of Sondex company, and domestic array electromagnetic wave water holdup meter, etc. The 12 micro-probes located in the circumferential direction can detect the properties of fluid media by using the differences in dielectric constants or resistivity physical properties between oil, gas, and water media. According to the logging information of the array probes, interpolation processing can be carried out, and then the medium distribution state of the wellbore cross-section can be inverted. According to different water holdup calculation methods, the average water holdup of the wellbore can be obtained. However, there are large errors in calculating the fluid holdup of horizontal wells and inclined well sections under complex flow pattern conditions by the existing average water holdup calculation methods of wellbores.

[0004] Currently, the more commonly used imaging methods include multi-linear interpolation method, inverse distance weighted interpolation method, Gaussian radial basis function interpolation method, and Kriging interpolation method. The inverse distance weighted interpolation method, Gaussian radial basis function interpolation method, and Kriging interpolation method consider the distance and distribution characteristics between probes, but do not consider the flow pattern characteristics of multiphase flow in horizontal gas wells; the multi-linear interpolation method fits a binary function based on the positions and holdup values of known measurement points, and estimates the attribute values of unknown points according to the fitted function, which can clearly divide the gas-water stratification interface, but lacks accuracy and can only be used for stratified flow. At present, the calculation methods of the average fluid holdup in the horizontal wellbore (such as weighted average method, grid interpolation method, equal height area weight coefficient method, and radial equal height area weight method, etc.) mainly aim at the stratified flow pattern. When applied to complex non-continuous medium distributions (such as slug flow, bullet flow, etc.), due to the extremely irregular distribution characteristics of the contact surfaces of multiphase fluid media, the calculated water holdup generally has large errors and cannot accurately reflect the true medium distribution in the horizontal wellbore.

[0005] In order to accurately invert the multiphase fluid distribution in the wellbore, it is necessary to develop a more accurate method for inverting the distribution of the wellbore fluid medium for complex flow patterns. In order to accurately and quantitatively calculate the water holdup under the conditions of complex flow patterns of gas-water two-phase fluids in horizontal gas wells in unconventional gas reservoirs, improve the inversion accuracy of the flow profile of horizontal wells, and support the high-precision evaluation of gas reservoir development, it is necessary to establish an accurate calculation method for the water holdup of slug flow for the array holdup meter. Summary of the Invention

[0006] The present application provides a method and system for inverting the medium distribution and calculating the water holdup of slug flow in horizontal gas wells to solve the problem that the existing calculation method for the average holdup of fluids in horizontal wellbores mainly targets stratified flow patterns. When applied to complex discontinuous medium distributions (such as slug flow, bullet flow, etc.), due to the extremely irregular distribution characteristics of the contact surface of multiphase fluid media, the calculated water holdup generally has a large error and cannot accurately reflect the true medium distribution in the horizontal wellbore.

[0007] According to a first aspect, in one embodiment, a method for inverting the medium distribution and calculating the water holdup of slug flow in horizontal gas wells is provided. The method includes:

[0008] Detect and obtain the response values of each probe of the array holdup meter in the fluid in the horizontal wellbore and perform normalization processing;

[0009] Taking the center of the horizontal wellbore as the origin, the horizontal direction as the x-axis, and the vertical direction as the y-axis, establish a coordinate system for the cross-section of the horizontal wellbore, obtain the position coordinates of each probe, and perform grid division on the cross-section of the horizontal wellbore based on the established coordinate system;

[0010] Project each probe onto the vertical y-axis, and sequentially judge the difference between the normalized values of the responses of two adjacent probes from top to bottom according to the projection positions. The two adjacent probes corresponding to the obtained minimum value are determined to be located in the gas-liquid mixed fluid region, and the maximum, minimum, and median coordinates of the gas-liquid mixed fluid regions on both sides of the wellbore circumference are obtained;

[0011] Based on the determined gas-liquid mixed fluid region, using the wet wall perimeter and the chord length corresponding to the wet wall fraction, introduce a constraint factor, establish an equation to obtain the arch height of the part enclosed by the gas-liquid arc interface to be solved and the chord length corresponding to the wet wall fraction, and obtain the maximum, minimum, and median coordinates of the gas-liquid mixed fluid region on the vertical line of the wellbore center;

[0012] Based on the interpolation extension algorithm for inverting the interface of the slug flow medium distribution, according to the maximum, minimum, and median coordinates of the gas-liquid mixed fluid regions on both sides of the wellbore circumference and on the vertical line of the wellbore center, and combining linear interpolation, obtain the gas-liquid arc interface equation of the maximum, minimum, and median values of the gas-liquid mixed fluid region. Based on the gas-liquid arc interface equation, use the interpolation method to assign the water holdup to the grid and complete the drawing of the water holdup imaging map of the wellbore cross-section;

[0013] By using the maximum and minimum coordinates of the gas-liquid mixed fluid region on both sides of the circumferential direction of the wellbore and on the vertical line at the center of the wellbore, an ellipse is constructed where the gas-liquid arc-shaped interface intersects the wellbore at three points. The upper part of the intersection of the ellipse and the wellbore is the gas section, and the lower part is the liquid section. Based on the constructed ellipse, the difference between the maximum liquid section area and the minimum liquid section area is obtained to get the area of the gas-liquid mixed fluid region, and then the average water holdup of the wellbore cross-section is calculated.

[0014] Furthermore, detect and obtain the response values of each probe of the array-type holdup meter in the fluid of the horizontal wellbore and perform normalization processing, specifically including:

[0015]

[0016] In the formula, Y t,j is the water holdup at the j-th probe in the horizontal wellbore, in decimal;

[0017] CWH j is the measured response value of the j-th probe in the horizontal wellbore, in counts per second;

[0018] CWH w,j is the response value of the j-th probe under full-water conditions, in counts per second;

[0019] CWH h,j is the response value of the j-th probe under full-gas conditions, in counts per second.

[0020] Furthermore, establish a coordinate system for the cross-section of the horizontal wellbore and obtain the position coordinates of each probe, specifically including:

[0021]

[0022] where R is the radius of the wellbore cross-section, in m;

[0023] α i is the angle between the position of the i-th probe without rotation and the vertical direction, in °;

[0024] θ is the azimuth angle of the holdup instrument, in °;

[0025] x i and y i are the horizontal and vertical coordinates of the position of the i-th probe respectively.

[0026] Furthermore, project each probe onto the vertical y-axis, and successively judge the difference between the normalized values of the responses of two adjacent probes from top to bottom according to the projection positions. The two adjacent probes corresponding to the obtained minimum value are determined to be located in the gas-liquid mixed fluid region, and the maximum, minimum, and median coordinates of the gas-liquid mixed fluid region on both sides of the wellbore circumference are obtained, specifically including:

[0027] Specify the mixed fluid interval S, and 0 < S < 1. When the normalized value of the probe response is less than Smin When it is gas, when the normalized value of the probe response is greater than S max When it is water;

[0028] Project the 12 holdup probes onto the vertical line, and judge the difference between the normalized values (Y i-1 , Y i ) of the responses of two adjacent probes in sequence from top to bottom according to the position. The two adjacent probes corresponding to the minimum value obtained are located in or near the mixed fluid region. Perform linear interpolation based on the vertical coordinates of the two probes and the corresponding normalized values of the probe responses to obtain S mid 、S min and S max corresponding vertical coordinates:

[0029]

[0030] Substitute the vertical coordinate results into the wellbore cross-section equation to obtain the abscissas of the corresponding positions on both sides of the wellbore circumference:

[0031]

[0032] Thus, the coordinates of the minimum, maximum, and median values of the mixed fluid region on both sides of the wellbore circumference are respectively (x min,left , y min,left ), (x max,left , y max,left ), (x mid,left , y mid,left ), (x min,right , y min,right ), (x max,right , y max,right ), (x mid,right , y mid,right ), and the corresponding water holdup values are S min,left 、S max,left 、S mid,left 、S min,right 、S max,right 、S mid,right , where y min,left = y min,right = y min , y max,left = y max,right = y max , y mid,left = y mid,right = y mid , S min,left = S min,right = S min 、S max,left = S max,right = S max 、S mid,left = S mid,right= S mid ;

[0033] where S min , S max , S mid are the minimum value, maximum value, and median value of the specified mixed fluid interval, respectively, in decimals;

[0034] Y t0 , Y t1 are the water holdup values of two adjacent probes located in the mixed fluid region obtained through judgment, with the ordinate of the latter being greater than that of the former, in decimals;

[0035] y t0 , y t1 are the ordinates of the positions of two adjacent probes located in the mixed fluid region obtained through judgment, with the latter being greater than the former;

[0036] y min , y max , y mid are the ordinates corresponding to S min , S max , S mid respectively.

[0037] Furthermore, based on the determined gas-liquid mixed fluid region, by using the wetted perimeter and the chord length corresponding to the wetted fraction, introducing a constraint factor, establishing an equation to obtain the arch height of the part enclosed by the chord length corresponding to the gas-liquid arc interface and the wetted fraction, and obtaining the maximum, minimum, and median coordinates of the gas-liquid mixed fluid region on the vertical line of the wellbore center, specifically including:

[0038] Equivalent the irregular interface between the gas phase and the liquid phase to an ideal arc structure, with the arc length varying between stratified smooth flow and cylindrical symmetric, closed annular flow. Therefore, interpolation processing is performed on the wetted perimeter and the chord length corresponding to the wetted fraction, and a constraint factor is introduced. The calculation formula is:

[0039]

[0040] The gas-liquid interface and the chord length corresponding to the wetted fraction also form a circular arc arch, where the arc length and the chord length are expressed as:

[0041] S I = βr a

[0042]

[0043] Combining the above two equations to form a system of equations to obtain the central angle β and the radius r a , then the arch height of the circular arc arch is expressed as:

[0044]

[0045] The maximum, minimum and median position coordinates of the fluid mixing fluid region on the vertical line of the wellbore center are obtained using probe data at different heights, and the holdup values are respectively assigned to S min,mid = S min , S mid,mid = S mid , S max,mid = S max , and the position coordinates are respectively expressed as:

[0046]

[0047] wherein, S L is the wetted perimeter, m;

[0048] S S is the chord length corresponding to the wetted wall fraction, m;

[0049] S I is the arc length of the gas-liquid interface, m;

[0050] k is a constraint factor, expressed as the ratio of the radial height Δy of the part surrounded by the gas slug and the chord length corresponding to the wetted wall fraction to the inner diameter of the wellbore, or dimensionless;

[0051] β is the central angle of the circular arc arch, °;

[0052] r a is the radius of the circle where the circular arc arch is located, m;

[0053] h ·,A respectively represent the maximum and minimum arch heights corresponding to the mixing fluid region, m;

[0054] θ c is the pipe inclination angle, °.

[0055] Furthermore, based on the intermittent flow medium distribution inversion interface interpolation extension algorithm, according to the maximum, minimum and median coordinates of the gas-liquid mixing fluid region on both sides of the wellbore circumference and on the vertical line of the wellbore center, and combined with linear interpolation, the gas-liquid arc-shaped interface equation of the maximum and minimum of the gas-liquid mixing fluid region is obtained. Based on the gas-liquid arc-shaped interface equation, the grid is assigned a water holdup using the interpolation method, specifically including:

[0056] The gas-liquid arc-shaped interfaces corresponding to the maximum, minimum and median of the mixing fluid region, and the arc-shaped interface equations are respectively:

[0057]

[0058] wherein, x i is the i-th abscissa from left to right;

[0059] y min,i 、ymid,i , y max,i are the minimum, median, and maximum ordinate values of the water holdup in the radial mixed fluid region corresponding to the i-th abscissa, respectively;

[0060] S min,i , S mid,i , S max,i are the minimum, median, and maximum values of the water holdup in the radial mixed fluid region corresponding to the i-th abscissa, respectively, in decimals.

[0061] Furthermore, based on the gas-liquid arc interface equation and using the interpolation method, the water holdup is assigned to the grid, and the water holdup imaging map of the wellbore cross-section is completed, specifically including:

[0062] All the horizontal and vertical coordinates and the corresponding water holdup values on the maximum and median arc interfaces of the mixed fluid region are obtained based on the gas-liquid arc interface equation. Quadratic linear interpolation is performed on each abscissa in the corresponding radial direction from left to right, and thus the water holdup can be assigned to each grid. The water holdup calculation formula for any point N on the wellbore cross-section is:

[0063]

[0064] If Y N > 1, it is assigned as 1, that is, Y N = 1; if Y N < 0, it is assigned as 0, that is, Y N = 0;

[0065] Y N is the water holdup value of any point N on the wellbore cross-section, in decimals;

[0066] Based on the obtained water holdup corresponding to the grid, color mapping is performed to complete the drawing of the water holdup imaging map of the wellbore cross-section.

[0067] Furthermore, using the maximum and minimum coordinates of the gas-liquid mixed fluid region on both sides of the wellbore circumference and on the vertical line of the wellbore center, an ellipse is constructed where the gas-liquid arc interface intersects the wellbore at three points. The upper part of the intersection of the ellipse and the wellbore is the gas section, and the lower part is the liquid section, specifically including:

[0068] Define the maximum and minimum points of the gas-liquid mixed fluid region on the vertical line of the wellbore center as {C min , C max} and the maximum and minimum points of the gas-liquid mixed fluid region on both sides of the wellbore circumference as {A min , A max ; B min , B max}; The standard ellipse rectangular coordinate equations corresponding to the maximum gas plug arc interface and the minimum gas plug arc interface are:

[0069]

[0070] It is considered that the upper part where the ellipse intersects the wellbore is the gas section, and the lower part is the liquid section. Taking the major axis of the ellipse as the radius to draw the circumscribed circle of the ellipse, then the area of the intersection part between the ellipse and the wellbore is calculated according to the local sector area of the circumscribed circle. The relationship between the ellipse and its circumscribed circle is as follows:

[0071]

[0072] The radial angle is from A min / A max , C min / C max The positional relationship is obtained as follows:

[0073]

[0074] Among them, a min , b min , a max , b max are the major and minor semi-axes of the ellipse corresponding to the largest arc air plug and the smallest arc air plug respectively, in m.

[0075] Furthermore, based on the constructed ellipse, the difference between the maximum liquid section area and the minimum liquid section area is obtained to get the area of the gas-liquid mixed fluid region, and then the average water holdup of the wellbore cross-section is calculated, specifically including:

[0076] According to the positional relationship between the ellipse, the circumscribed circle and the wellbore, and the ordinate of the C min / C max point, an equation related to the major semi-axis of the ellipse is established, and a system of equations is established:

[0077]

[0078] Solve the equations to obtain the major and minor semi-axes a min , b min , a max , b max , then the maximum liquid section area and the minimum liquid section area are respectively:

[0079]

[0080] Subtract the two areas to get the area of the mixed fluid region:

[0081] A M =A L,min -A L,max

[0082] Then the water holdup of the liquid film section is:

[0083]

[0084] Among them, A′ min, B' min , A' max , B' max are respectively A min , B min , A max , B max the intersection points of the horizontal extension lines and the circumscribed circle;

[0085] O' min / O' max is the center of the ellipse and its circumscribed circle;

[0086] are respectively the areas of triangles A min O' min B min , A max O' max B max , A' max O' max B' max , A' min O' min B' min , m 2 ;

[0087] |A min C min |, |A min，x C min,x |, |A min,y C min,y |(|A max C max |, |A max,x C max,x |, |A max,y C max,y |) are respectively the distances from points A min , C min , A max , C max to the horizontal distance and the vertical distance, m;

[0088] θ 0,min is the angle between the line connecting points B min , C min and the central perpendicular line, °;

[0089] θ 0,max is the angle between the line connecting points B max , C max and the central perpendicular line, °;

[0090] θ 1,min is the angle between the perpendicular line from the center of the shaft to point B min and the central perpendicular line, °;

[0091] θ1,max is the included angle between the perpendicular line from the center of the wellbore to point B max and the central perpendicular line, °;

[0092] θ 2,min is the included angle between the perpendicular line from the midpoint of the ellipse to point B′ min and the central perpendicular line, °;

[0093] θ 2,max is the included angle between the perpendicular line from the midpoint of the ellipse to point B′ max and the central perpendicular line, °;

[0094] A L,min and A L,max are respectively the maximum liquid segment area and the minimum liquid segment area of the wellbore cross-section, m 2 ;

[0095] A t is the cross-sectional area of the wellbore, m 2 ;

[0096] Y M is the holdup in the mixed fluid region, expressed as the weighted average of the holdups of the probes in the mixed fluid region, decimal;

[0097] Y w is the water holdup in the liquid film section of intermittent flow, decimal.

[0098] According to a second aspect, in an embodiment, a system for inverting the medium distribution and calculating the water holdup of intermittent flow in a horizontal gas well is provided, and the system includes:

[0099] A measurement module, configured to detect and obtain the response values of each probe of the array holdup meter in the fluid in the horizontal wellbore and perform normalization processing;

[0100] A coordinate system construction module, configured to establish a coordinate system for the cross-section of the horizontal wellbore with the center of the horizontal wellbore as the origin, the horizontal direction as the x-axis direction, and the perpendicular direction as the y-axis direction, obtain the position coordinates of each probe, and perform grid division on the cross-section of the horizontal wellbore based on the established coordinate system;

[0101] A mixed fluid region determination module, configured to project each probe onto the perpendicular y-axis, sequentially judge the difference between the normalized values of the responses of two adjacent probes from top to bottom according to the projection positions, determine the two adjacent probes corresponding to the minimum value obtained as being located in the gas-liquid mixed fluid region, and obtain the maximum, minimum, and median coordinates of the gas-liquid mixed fluid regions on both sides of the wellbore circumference;

[0102] The gas-liquid interface lowest point determination module is used to, based on the determined gas-liquid mixed fluid region, utilize the wetted perimeter and the chord length corresponding to the wetted fraction, introduce a constraint factor, establish an equation to obtain the arch height of the part enclosed by the chord length corresponding to the gas-liquid arc-shaped interface to be determined and the wetted fraction, and obtain the maximum value, minimum value and median coordinate of the gas-liquid mixed fluid region on the vertical line of the wellbore center.

[0103] The interface interpolation and extension module is used to, based on the intermittent flow medium distribution inversion interface interpolation and extension algorithm, according to the maximum value, minimum value and median coordinate of the gas-liquid mixed fluid region on both sides of the wellbore circumference and on the vertical line of the wellbore center, and combine linear interpolation to obtain the gas-liquid arc-shaped interface equation of the maximum value, minimum value and median of the gas-liquid mixed fluid region. Based on the gas-liquid arc-shaped interface equation, use the interpolation method to assign the water holdup to the grid, and complete the drawing of the water holdup imaging map of the wellbore cross-section.

[0104] The circle-ellipse model construction module is used to utilize the maximum and minimum value coordinates of the gas-liquid mixed fluid region on both sides of the wellbore circumference and on the vertical line of the wellbore center to construct an ellipse where the gas-liquid arc-shaped interface intersects the wellbore at three points. The upper part of the intersection of the ellipse and the wellbore is the gas section, and the lower part is the liquid section. Based on the constructed ellipse, obtain the difference between the maximum liquid section area and the minimum liquid section area to get the area of the gas-liquid mixed fluid region, and further obtain the average water holdup of the wellbore cross-section.

[0105] The present application provides a method and system for inverting the intermittent flow medium distribution and calculating the water holdup of a horizontal gas well, having the following beneficial effects:

[0106] (1) The interface interpolation and extension method established by the present invention can accurately invert the gas core characteristics of the liquid film section in intermittent flow and the arc-shaped interface between the gas-liquid two phases, laying a foundation for the accurate evaluation of the production dynamics of complex flows.

[0107] (2) The present invention can break through the limitations of the existing calculation methods for horizontal wells, calculate the holdups of slug flow and plug flow, and is of great significance for the evaluation of the production dynamics of horizontal wells in unconventional oil and gas reservoirs.

[0108] (3) The present invention innovatively proposes a circle-ellipse segmentation model, which is not limited to the transverse segmentation of the wellbore cross-section. The arc-shaped segmentation is more in line with the gas-liquid medium distribution in the complex flow of actual horizontal wells, effectively improving the accuracy of holdup calculation. Description of the Drawings

[0109] Figure 1 It is a schematic diagram of the grid division of the wellbore cross-section in a method for inverting the intermittent flow medium distribution and calculating the water holdup of a horizontal gas well provided by an embodiment of the present invention;

[0110] Figure 2 It is a schematic diagram of the equivalent gas-liquid interface in a method for inverting the intermittent flow medium distribution and calculating the water holdup of a horizontal gas well provided by an embodiment of the present invention;

[0111] Figure 3 Schematic diagram of the interpolation process of the interface interpolation extension method in a method for inverting the medium distribution and calculating the water holdup of intermittent flow in a horizontal gas well provided by an embodiment of the present invention;

[0112] Figure 4 Schematic diagram of the circle-ellipse model in a method for inverting the medium distribution and calculating the water holdup of intermittent flow in a horizontal gas well provided by an embodiment of the present invention;

[0113] Figure 5 Comparison diagram of imaging results of array water holdup monitoring data in a method for inverting the medium distribution and calculating the water holdup of intermittent flow in a horizontal gas well provided by an embodiment of the present invention;

[0114] Figure 6 Comparison diagram of water holdup calculation results of array water holdup monitoring data in a method for inverting the medium distribution and calculating the water holdup of intermittent flow in a horizontal gas well provided by an embodiment of the present invention. Detailed implementation manners

[0115] The present invention will be further described in detail below in conjunction with the accompanying drawings through specific implementation manners. Similar elements in different implementation manners are labeled with related similar element numbers. In the following implementation manners, many detailed descriptions are provided to enable a better understanding of the present application. However, those skilled in the art can easily recognize that some of the features can be omitted in different situations, or can be replaced by other elements, materials, or methods. In some cases, some operations related to the present application are not shown or described in the specification to avoid overwhelming the core part of the present application with excessive descriptions. For those skilled in the art, it is not necessary to describe these related operations in detail, and they can fully understand the related operations based on the descriptions in the specification and general technical knowledge in the art.

[0116] In addition, the features, operations, or characteristics described in the specification can be combined in any appropriate manner to form various implementation manners. At the same time, the steps or actions in the method description can also be reordered or adjusted in an obvious manner by those skilled in the art. Therefore, the various sequences in the specification and drawings are only for clearly describing a certain embodiment and do not mean a necessary sequence unless it is stated that a certain sequence must be followed.

[0117] The first embodiment of the present invention provides a method for inverting the medium distribution and calculating the water holdup of intermittent flow in a horizontal gas well, which will be described in detail below.

[0118] In step S100, the response values of each probe of the array water holdup meter in the fluid in the horizontal wellbore are detected and obtained and normalized.

[0119] Specifically, based on the calibration values of the probes of each holdup instrument (CAT, RAT, array electromagnetic wave holdup instrument) in pure water and pure gas, the water holdup values at each probe position are obtained through normalization. The calculation formula is as follows:

[0120]

[0121] In the formula, Y t,j is the water holdup at the j-th (j = 1, 2,..., 12) array probe in the horizontal wellbore, in decimal;

[0122] CWH j is the measured response value of the j-th probe in the horizontal wellbore, in counts per second (CPS);

[0123] CWH w,j is the response value of the j-th probe under full water condition, in counts per second (CPS);

[0124] CWH h,j is the response value of the j-th probe under full gas condition, in counts per second (CPS).

[0125] In step S200, with the center of the horizontal wellbore as the origin, the horizontal direction as the x-axis, and the vertical direction as the y-axis, a coordinate system is established for the cross-section of the horizontal wellbore. The coordinates of each probe position are obtained, and the cross-section of the horizontal wellbore is divided into grids based on the established coordinate system.

[0126] Specifically, to establish a coordinate system for the wellbore cross-section to determine the probe positions, with the center of the wellbore as the origin, the horizontal right direction as the positive x-axis, and the vertical upward direction as the y-axis. Then, according to the wellbore radius, the azimuth angle of the holdup instrument, and the angles between the positions of each probe without rotation and the vertical direction (the angles for No. 1 - 12 are α i = 0, 30,..., 330), the coordinates of each probe position are respectively (x i , y i ). Then, the cross-section of the wellbore is divided into grids based on the established coordinate axes.

[0127]

[0128] where R is the radius of the wellbore cross-section, in m;

[0129] α i is the angle between the position of the i-th probe without rotation and the vertical direction, in °;

[0130] θ is the azimuth angle of the holdup instrument, in °;

[0131] x i , y i are respectively the horizontal and vertical coordinates of the i-th probe position.

[0132] Figure 1 It is a schematic diagram of the wellbore cross-section grid division. The horizontal and vertical coordinates of the holdup probe position are calculated using the wellbore parameters and the measured azimuth angle of the instrument, and a grid is established with adjustable grid density.

[0133] In step S300, project each probe onto the vertical line y-axis, and successively judge the difference in the normalized values of the responses of two adjacent probes from top to bottom according to the projection positions. The two adjacent probes corresponding to the obtained minimum value are determined to be located in the gas-liquid mixed fluid region, and the minimum, maximum, and median coordinates of the gas-liquid mixed fluid regions on both sides of the wellbore circumference are obtained.

[0134] Specifically, a mixed fluid interval S (0 < S < 1) is specified. When the normalized value of the probe response is less than S min , it is indicated as gas. When the normalized value of the probe response is greater than S max , it is indicated as water; project the 12 holdup probes onto the vertical line, and successively judge the difference in the normalized values of the responses of two adjacent probes (Y i-1 , Y i ) from top to bottom according to the positions. The two adjacent probes corresponding to the obtained minimum value are located in the mixed fluid region (or nearby). According to the vertical coordinates of these two probes and the corresponding normalized values of the probe responses, linear interpolation is performed to obtain S mid (linear interpolation), S min and S max (linear extrapolation) corresponding vertical coordinates.

[0135]

[0136] Substitute the above results into the wellbore cross-section equation to obtain the abscissas of the corresponding positions on both sides of the wellbore.

[0137]

[0138] Thus, the coordinates of the minimum, maximum, and median values of the mixed fluid regions on both sides of the wellbore can be obtained as (x min,left , y min,left ), (x max,left , y max,left ), (x mid,left , y mid,left ), (x min,right , y min,right ), (x max,right , y max,right ), (x mid,right , y mid,right ), and the corresponding water holdup values are S min,left , S max,left , S mid,left , S min,right , S max,right , S mid,right , where y min,left= y min,right = y min ,y max,left = y max,right = y max ,y mid,left = y mid,right = y mid ,S min,left = S min,right = S min ,S max,left＝ S max,right = S max ,S mid,left＝ S mid,right = S mid ,

[0139] Wherein, S min 、S max 、S mid are respectively the minimum value, maximum value, and median value of the specified mixed fluid interval, in decimals;

[0140] Y t0 ,Y t1 are respectively the water holdup values of two adjacent probes located in the mixed fluid region obtained through judgment, with the ordinate of the latter being greater than that of the former, in decimals;

[0141] y t0 ,y t1 are respectively the ordinates of the positions of two adjacent probes located in the mixed fluid region obtained through judgment, with the latter being greater than the former;

[0142] y min ,y max ,y mid are respectively min 、S max 、S mid the corresponding position ordinates.

[0143] In step S400, based on the determined gas-liquid mixed fluid region, using the wet wall perimeter and the chord length corresponding to the wet wall fraction, introducing a constraint factor, an equation is established to obtain the arch height of the part enclosed by the chord length corresponding to the wet wall fraction of the gas-liquid arc-shaped interface to be determined, and the maximum value, minimum value, and median coordinate of the gas-liquid mixed fluid region on the vertical line of the wellbore center are obtained.

[0144] Specifically, this embodiment provides a gas-liquid interface arc length estimation formula, which equivalent the irregular interface between the gas phase and the liquid phase to an ideal arc-shaped structure. The arc length varies between stratified smooth flow and cylindrical symmetry, closed annular flow. Therefore, interpolation processing is performed on the wet wall perimeter and the chord length corresponding to the wet wall fraction, and a constraint factor is introduced. The calculation formula is

[0145]

[0146] The gas-liquid interface and the chord length corresponding to the wet wall fraction also form an arc arch, where the arc length and chord length can be expressed as,

[0147] S I =βr a (12)

[0148]

[0149] Combining the above two equations to form an equation system, we can obtain the central angle (β) and radius (r a ), then the height of the circular arch can be expressed as,

[0150]

[0151] According to the above derivation, the threshold and median position coordinates of the fluid mixing area on the vertical line of the wellbore center can be obtained by using the probe data at different heights. The holding rate values are assigned to S min,mid =S min , S mid,mid =S mid , S max,mid =S max , the position coordinates are expressed as,

[0152]

[0153] Among them, S L is the wet wall perimeter, m;

[0154] S S is the chord length corresponding to the wet wall fraction, m;

[0155] S I is the arc length of the gas-liquid interface, m;

[0156] k is the constraint factor, which is expressed as the ratio of the radial height Δy of the part enclosed by the chord length corresponding to the gas plug and wet wall fraction to the inner diameter of the wellbore. or dimensionless;

[0157] β is the central angle of the circular arch, °;

[0158] r a is the radius of the circle where the circular arch is located, m;

[0159] h ·,A They represent the maximum and median heights of the mixed area, m;

[0160] θ c is the pipe inclination, °.

[0161] Figure 2It is an equivalent schematic diagram of the gas-liquid interface. Based on the determined probe position, the mixing region is determined. Using the wetted wall perimeter and the chord length corresponding to the wetted wall fraction, a constraint factor is introduced, and an equation is established to obtain the arch height of the part enclosed by the chord length corresponding to the wetted wall fraction of the gas-liquid arc interface to be determined, and then the position of the lowest point of the gas-liquid interface can be determined, and the gas-liquid arc interface can be determined accordingly.

[0162] In step S500, based on the intermittent flow medium distribution inversion interface interpolation and extension algorithm, according to the maximum, minimum and median coordinates of the gas-liquid mixed fluid region on both sides of the wellbore circumference and on the vertical line of the wellbore center, and combined with linear interpolation, the gas-liquid arc interface equation of the maximum, minimum and median of the gas-liquid mixed fluid region is obtained. Based on the gas-liquid arc interface equation, the water holdup of the grid is assigned by using the interpolation method, and the water holdup imaging map of the wellbore cross-section is completed.

[0163] Specifically, an intermittent flow medium distribution inversion interface interpolation and extension algorithm is proposed. Based on the coordinate trend arcs of the maximum, minimum and median of the mixing region obtained from the above analysis and three key points on the curve, the arc interface corresponding to the maximum, minimum and median of the mixing region can be obtained by combining quadratic linear interpolation. The arc interface equations are respectively

[0164]

[0165] Based on the above arc equations, all the horizontal and vertical coordinates on the maximum arc interface and the median arc interface of the mixing region, as well as the corresponding water holdup values, can be obtained. Quadratic linear interpolation is performed in the corresponding radial direction for each horizontal coordinate from left to right, and the water holdup of each grid can be assigned. The water holdup calculation formula for any point N on the wellbore cross-section is

[0166]

[0167] If Y N > 1, it is assigned as 1, that is, Y N = 1; if Y N < 0, it is assigned as 0, that is, Y N = 0.

[0168] Finally, based on the obtained water holdup corresponding to the grid, color mapping is performed to complete the drawing of the water holdup imaging map of the wellbore cross-section.

[0169] In the formula, x i is the i-th horizontal coordinate from left to right;

[0170] y min,i 、y mid,i 、y max,i are the vertical coordinates of the minimum, median and maximum water holdup of the mixing region in the radial direction corresponding to the i-th horizontal coordinate respectively;

[0171] S min,i 、S mid,i, S max,i are respectively the minimum value, median value, and maximum value of the water holdup in the radial mixing region corresponding to the i-th abscissa, in decimals;

[0172] Y N is the water holdup value of any point N on the wellbore cross-section, in decimals.

[0173] Figure 3 is a schematic diagram of the interpolation process of the interface interpolation extension method. The water holdup probe is symmetrically projected, and the gas-liquid mixing regions on both sides are divided based on the ordinate and water holdup response values of the probes on both sides. Then, the thresholds of the mixing regions on both sides and the equivalent probe positions of the median values are misaligned and radially projected. Combining with the position of the lowest point of the gas-liquid interface, the radial gas-liquid mixing region is divided, and then the water holdup is assigned to the grid by interpolation.

[0174] Figure 5 is a comparison diagram of the imaging results of the array water holdup monitoring data in the example. It can be seen from the figure that for the wellbore cross-section inverted by the interface interpolation extension method, the gas core in the intermittent flow liquid film section is the most intuitive and clear, and the imaging is the most reasonable.

[0175] In step S600, using the maximum and minimum coordinate values of the gas-liquid mixed fluid region on both sides of the wellbore circumference and on the vertical line of the wellbore center, an ellipse is constructed where the gas-liquid arc interface intersects the wellbore at three points. The upper part of the intersection of the ellipse and the wellbore is the gas section, and the lower part is the liquid section. Based on the constructed ellipse, the difference between the maximum liquid section area and the minimum liquid section area is obtained to get the area of the gas-liquid mixed fluid region, and then the average water holdup of the wellbore cross-section is calculated.

[0176] Specifically, Figure 4 is a schematic diagram of the circle-ellipse model. Using the threshold values of the mixing regions on both sides of the wellbore and the equivalent probe positions of the median values and the position of the lowest point of the gas-liquid interface, an ellipse is constructed that intersects the wellbore at these three points. The upper part of the intersection of the ellipse and the wellbore is the gas section, and the lower part is the liquid section.

[0177] This embodiment provides a "circle-ellipse" model for calculating the water holdup in intermittent flow. From the derivation in the previous part, the threshold nodes {C min , C max} of the mixing region on the vertical line of the wellbore interface center and the threshold positions {A min , A max ; B min , B max} of the mixing region around the wellbore circumference are obtained. An ellipse where the gas-water arc interface intersects the wellbore is extended. Then, the standard ellipse rectangular coordinate equations corresponding to the maximum gas slug arc interface and the minimum gas slug arc interface are respectively,

[0178]

[0179]

[0180] a is the semi-major axis of the ellipse; where, a min , b min , a max , b max are the semi-major and semi-minor axes of the ellipse corresponding to the largest arc air plug and the smallest arc air plug respectively, m;

[0181] It is considered that the upper part where the ellipse intersects the wellbore is the gas section and the lower part is the liquid section. Taking the major axis of the ellipse as the radius to make the circumscribed circle of the ellipse, then the area of the intersection part of the ellipse and the wellbore can be obtained according to the local sector area of the circumscribed circle. The ellipse and its circumscribed circle have the following relationship,

[0182]

[0183] The radial angle can be obtained from the positional relationship of A min (A max ), C min (C max );

[0184]

[0185] According to the positional relationship between the ellipse, the circumscribed circle and the wellbore, and the vertical coordinates of points C min , C max , establish an equation related to the semi-major axis of the ellipse, and establish a system of equations based on the above analysis,

[0186]

[0187] Solve the equations to obtain the semi-major and semi-minor axes a min , b min , a max , b max , then the maximum liquid section area and the minimum liquid section area can be obtained as,

[0188]

[0189] Subtract the two areas to get the mixed area,

[0190] A M = A L,min - A L,max (32)

[0191] Then the water holdup of the liquid film section is,

[0192]

[0193] where, A′ min , B′ min (A′ max , B′ max ) are A min , B min (Amax , B max ) The intersection point of the horizontal extension line and the circumscribed circle;

[0194] O′ min (O′ max ) is the center of the ellipse and its circumscribed circle;

[0195] are respectively the areas of triangle A min O′ min B min (A max O′ max B max ) and triangle A′ max O′ max B′ max (A′ min O′ min B′ min ), m 2 ;

[0196] |A min C min |, |A min，x C min,x |, |A min,y C min,y |(|A max C max |, |A max,x C max,x |, |A max,y C max,y |) are respectively the distances between points A min , C min (A max , C max ) and the horizontal and vertical distances, m;

[0197] θ 0,min (θ 0,max ) is the angle between the line connecting points B min , C min (B max , C max ) and the central perpendicular line, °;

[0198] θ 1,min (θ 1,max ) is the angle between the perpendicular line from the center of the wellbore to point B min (B max ) and the central perpendicular line, °;

[0199] θ 2,min (θ 2,max ) is the angle between the perpendicular line from the midpoint of the ellipse to point B′ min (B′ max ) and the central perpendicular line, °;

[0200] A L,min and A L,max are the maximum liquid segment area and the minimum liquid segment area of the wellbore cross-section, respectively, in m 2 ;

[0201] A t is the wellbore cross-sectional area, in m 2 ;

[0202] Y M is the holdup in the mixing zone, expressed as the weighted average of the probe holdups in the mixing zone, in decimal;

[0203] Y w is the water holdup in the intermittent flow liquid film section, in decimal.

[0204] In this example experiment, the simulated fluids are air and tap water, the flow tube is a transparent plexiglass tube with an inner diameter of 120 mm and a length of 10 m. The entire experiment is completed under laboratory standard conditions. By simulating the state of a horizontal wellbore (well deviation angle of 75°) with a water cut of 40%, the responses of the array capacitance water holdup meter are measured under the conditions of total flow rates of 50, 100, 200, 300, and 400 m³ / day in sequence. During the experiment, the array probes are fully opened, and the water holdup values after processing for each array probe are as follows:

[0205]

[0206] Based on the obtained holdup values of each probe, the wellbore holdup is calculated using the weighted average method, the equal-height area weight method, the radial midpoint area weight method, and the "circle-ellipse" model of the present invention respectively. The calculated wellbore holdup is compared with the closed-in wellbore holdup, and the comparison of the calculation results is as follows:

[0207]

[0208]

[0209] Figure 6 is the comparison chart of the water holdup calculation results of the array holdup monitoring data in the example. The figure shows that the relative errors between the calculation results of all measurement points of the "circle-ellipse" model and the closed-in water holdup are all within 3%. Compared with other traditional methods, the "circle-ellipse" model has the highest coincidence rate with the closed-in water holdup and the widest applicable range.

[0210] The interface interpolation extension algorithm of the present invention has a high consistency with the characteristics of the actual wellbore intermittent flow, and the error range between the water holdup value calculated by the "circle-ellipse" model of the present invention and the experimental closed-in water holdup is the smallest.

[0211] Corresponding to the above-disclosed method for inverting the medium distribution and calculating the water holdup of intermittent flow in a horizontal gas well, an embodiment of the present invention also discloses a system for inverting the medium distribution and calculating the water holdup of intermittent flow in a horizontal gas well, which specifically includes:

[0212] A measurement module, configured to detect and obtain the response values of each probe of the array-type holdup meter in the fluid of the horizontal wellbore and perform normalization processing;

[0213] A coordinate system construction module, configured to establish a coordinate system for the cross-section of the horizontal wellbore with the center of the horizontal wellbore as the origin, the horizontal direction as the x-axis direction, and the vertical direction as the y-axis direction, obtain the position coordinates of each probe, and perform grid division on the cross-section of the horizontal wellbore based on the established coordinate system;

[0214] A mixed fluid region determination module, configured to project each probe onto the vertical y-axis, sequentially judge the difference between the normalized values of the responses of two adjacent probes from top to bottom according to the projection positions, determine the two adjacent probes corresponding to the minimum value obtained as being located in the gas-liquid mixed fluid region, and obtain the maximum value, minimum value, and median coordinate of the gas-liquid mixed fluid region on both sides of the wellbore circumference;

[0215] A lowest point determination module of the gas-liquid interface, configured to, based on the determined gas-liquid mixed fluid region, utilize the wet wall perimeter and the chord length corresponding to the wet wall fraction, introduce a constraint factor, establish an equation to obtain the arch height of the part surrounded by the chord length corresponding to the wet wall fraction of the to-be-determined gas-liquid arc-shaped interface, and obtain the maximum value, minimum value, and median coordinate of the gas-liquid mixed fluid region on the vertical line of the wellbore center;

[0216] An interface interpolation and extension module, configured to, based on the interface interpolation and extension algorithm for inverting the medium distribution of intermittent flow, obtain the gas-liquid arc-shaped interface equation of the maximum value and median value of the gas-liquid mixed fluid region according to the maximum value, minimum value, and median coordinate of the gas-liquid mixed fluid region on both sides of the wellbore circumference and on the vertical line of the wellbore center and combine linear interpolation, assign the water holdup to the grid based on the gas-liquid arc-shaped interface equation and use the interpolation method, and complete the drawing of the water holdup imaging map of the wellbore cross-section;

[0217] A circle-ellipse model construction module, configured to utilize the maximum and minimum value coordinates of the gas-liquid mixed fluid region on both sides of the wellbore circumference and on the vertical line of the wellbore center to construct an ellipse where the gas-liquid arc-shaped interface intersects the wellbore at three points. The upper part of the intersection of the ellipse and the wellbore is the gas section, and the lower part is the liquid section. Based on the constructed ellipse, obtain the difference between the maximum liquid section area and the minimum liquid section area to obtain the area of the gas-liquid mixed fluid region, and further obtain the average water holdup of the wellbore cross-section.

[0218] It should be noted that for the detailed description of a system for inverting the medium distribution and calculating the water holdup of intermittent flow in a horizontal gas well provided by an embodiment of the present invention, reference can be made to the relevant description of a method for inverting the medium distribution and calculating the water holdup of intermittent flow in a horizontal gas well provided by an embodiment of the present application, which will not be elaborated here.

[0219] The above uses specific examples to illustrate the present invention, which is only for helping to understand the present invention and is not intended to limit the present invention. For those skilled in the technical field to which the present invention pertains, several simple deductions, deformations or substitutions can also be made according to the idea of the present invention.

Claims

1. A method for inverting the medium distribution of intermittent flow in a horizontal gas well and calculating the water holdup, characterized in that, The method includes: Detecting and obtaining the response values of each probe of the array holdup meter in the fluid of the horizontal wellbore and performing normalization processing; Taking the center of the horizontal wellbore as the origin, the horizontal direction as the x-axis direction, and the vertical direction as the y-axis direction, establishing a coordinate system for the cross-section of the horizontal wellbore, obtaining the position coordinates of each probe, and dividing the cross-section of the horizontal wellbore into grids based on the established coordinate system; Projecting each probe onto the vertical y-axis, sequentially judging the difference between the normalized values of the responses of two adjacent probes from top to bottom according to the projection positions, determining the two adjacent probes corresponding to the obtained minimum value as being located in the gas-liquid mixed fluid region, and obtaining the maximum, minimum, and median coordinates of the gas-liquid mixed fluid regions on both sides of the wellbore circumference; Based on the determined gas-liquid mixed fluid region, using the wetted perimeter and the chord length corresponding to the wetted fraction, introducing a constraint factor, establishing an equation to obtain the arch height of the part enclosed by the to-be-determined gas-liquid arc interface and the chord length corresponding to the wetted fraction, and obtaining the maximum, minimum, and median coordinates of the gas-liquid mixed fluid region on the vertical line at the center of the wellbore; Based on the intermittent flow medium distribution inversion interface interpolation extension algorithm, according to the maximum, minimum, and median coordinates of the gas-liquid mixed fluid regions on both sides of the wellbore circumference and on the vertical line at the center of the wellbore, and combining linear interpolation to obtain the gas-liquid arc interface equation of the maximum, minimum, and median values of the gas-liquid mixed fluid region, performing holdup rate assignment to the grid based on the gas-liquid arc interface equation and using the interpolation method, and completing the drawing of the holdup rate imaging map of the wellbore cross-section; Using the maximum and minimum coordinate values of the gas-liquid mixed fluid regions on both sides of the wellbore circumference and on the vertical line at the center of the wellbore, constructing an ellipse where the gas-liquid arc interface intersects the wellbore at three points, the upper part of the intersection of the ellipse and the wellbore is the gas section, and the lower part is the liquid section, obtaining the difference between the maximum liquid section area and the minimum liquid section area based on the constructed ellipse to get the area of the gas-liquid mixed fluid region, and further obtaining the average holdup rate of the wellbore cross-section; 2. The method for inverting the intermittent flow medium distribution and calculating the water holdup rate of a horizontal gas well according to claim 1, wherein Detecting and obtaining the response values of each probe of the array holdup meter in the fluid of the horizontal wellbore and performing normalization processing, specifically including: where Y t,j is the water holdup at the j-th probe in the horizontal wellbore, in decimals; CWH j is the measured response value of the j-th probe in the horizontal wellbore, counts per second; CWH w,j is the response value of the j-th probe under full water conditions, counts per second; CWH h,j It is the response value of the j-th probe under full gas condition, the count rate per second.

3. The method for inverting the intermittent flow medium distribution and calculating the water holdup of a horizontal gas well according to claim 1, wherein Establishing a coordinate system for the cross-section of the horizontal wellbore and obtaining the position coordinates of each probe, specifically including: where R is the radius of the cross-section of the wellbore, in m; α i is the angle between the position of the i-th probe without rotation and the vertical direction, °; θ is the azimuth angle of the holdup meter, in °; x i and y i are respectively the horizontal and vertical coordinates of the i-th probe position.

4. A method for inverting the medium distribution of intermittent flow in a horizontal gas well and calculating the water holdup, as described in claim 1, characterized in that Projecting each probe onto the vertical y-axis, sequentially judging the difference between the normalized values of the responses of two adjacent probes from top to bottom according to the projection positions, determining the two adjacent probes corresponding to the obtained minimum value as being located in the gas-liquid mixed fluid region, and obtaining the maximum, minimum, and median coordinates of the gas-liquid mixed fluid regions on both sides of the wellbore circumference, specifically including: Specify the mixed fluid interval S, where 0 < S < 1. When the normalized probe response value is less than S min it is represented as gas. When the normalized probe response value is greater than S max it is represented as water; Project 12 holdup probes onto the vertical line, and judge the difference between the normalized values (Y i-1 ,Y i ) of the responses of two adjacent probes in sequence from top to bottom according to the positions. The two adjacent probes corresponding to the minimum value obtained are located in or near the mixed fluid region. Linear interpolation is performed based on the vertical coordinates of the two probes and the corresponding normalized probe responses to obtain S mid 、S min and S max corresponding vertical coordinates: Substituting the ordinate result into the wellbore cross-section equation to obtain the abscissas of the corresponding positions on both sides of the wellbore circumference; The coordinates at the minimum, maximum, and median values of the mixed fluid region on both sides of the wellbore circumference are respectively (x min,left , y min,left ), (x max,left , y max,left ), (x mid,left , y mid,left ), (x min,right , y min,right ), (x max,right , y max,right ), (x mid,right , y mid,right ), and the corresponding water holdup values are S min,left , S max,left , S mid,left , S min,right , S max,right , S mid,right . Among them, y min,left = y min,right = y min , y max,left = y max,right = y max , y mid,left = y mid,right = y mid , S min,left = S min,right = S min , S max,left＝ S max,right = S max , S mid,left＝ S mid,right = S mid ; Among them, S min , S max , S mid are respectively the minimum value, maximum value, and median value of the specified mixed fluid interval, in decimals; Y t0 and Y t1 are respectively two adjacent probe water holdup values located in the mixed fluid region obtained through judgment, with the ordinate of the latter being greater than that of the former, in decimals; y t0 ,y t1 are respectively the vertical coordinates of two adjacent probe positions located in the mixed fluid region obtained through judgment, with the latter being greater than the former; y min ,y max ,y mid are the ordinates of the corresponding positions of S min , S max , S mid respectively.

5. A method for inverting the medium distribution and calculating the water holdup of intermittent flow in a horizontal gas well according to claim 4, characterized in that, Based on the determined gas-liquid mixed fluid region, using the wetted perimeter and the chord length corresponding to the wetted fraction, introducing a constraint factor, establishing an equation to obtain the arch height of the part enclosed by the to-be-determined gas-liquid arc interface and the chord length corresponding to the wetted fraction, and obtaining the maximum, minimum, and median coordinates of the gas-liquid mixed fluid region on the vertical line at the center of the wellbore, specifically including: Equivalently converting the irregular interface between the gas phase and the liquid phase into an ideal arc structure, the arc length varies between stratified smooth flow and cylindrical symmetric, closed annular flow, so interpolation processing is performed on the wetted perimeter and the chord length corresponding to the wetted fraction, and a constraint factor is introduced, and the calculation formula is: The gas-liquid interface and the chord length corresponding to the wet-wall fraction also form a circular arc arch, where the arc length and the chord length are expressed as: S I ＝βr a Solve the above two equations simultaneously to form a system of equations to obtain the central angle β and the radius r a , then the arch height of the circular arc arch is expressed as: The maximum, minimum, and median position coordinates of the fluid mixing fluid region on the vertical line of the wellbore center are obtained using probe data at different heights, and the holdup values are respectively assigned to S min,mid = S min , S mid,mid = S mid , S max,mid = S max , and the position coordinates are respectively expressed as: where S L is the wetted wall perimeter, m; S S The chord length corresponding to the wet-wall fraction, m; S I is the arc length of the gas-liquid interface, m; k is a constraint factor, expressed as the ratio of the radial height Δy of the part surrounded by the chord length corresponding to the gas plug and the wet wall fraction to the inner diameter of the wellbore, or dimensionless; β is the central angle of the circular arc arch, °; r a Radius of the circle where the circular arc arch is located, m; h ·,A respectively represent the maximum and minimum values of the mixed fluid region and the corresponding arch heights of the median value, m; θ c is the pipeline inclination angle, °.

6. The method for inverting the intermittent flow medium distribution and calculating the water holdup rate of a horizontal gas well according to claim 5, wherein Based on the intermittent flow medium distribution inversion interface interpolation extension algorithm, according to the maximum, minimum and median coordinates of the gas-liquid mixed fluid region on both sides of the wellbore circumference and on the central vertical line of the wellbore, and combined with linear interpolation to obtain the gas-liquid arc interface equation of the maximum, minimum and median of the gas-liquid mixed fluid region. Based on the gas-liquid arc interface equation, the water holdup of the grid is assigned by using the interpolation method, which specifically includes: The gas-liquid arc interfaces corresponding to the maximum, minimum and median of the mixed fluid region, and the arc interface equations are respectively: where x i is the i-th abscissa from left to right; y min,i 、y mid,i 、y max,i are the minimum, median, and maximum ordinate values of the water holdup in the radially mixed fluid region corresponding to the i-th abscissa, respectively; S min,i 、S mid,i 、S max,i are respectively the minimum value, median value, and maximum value of the water holdup in the mixed fluid region corresponding to the i-th abscissa, in decimals.

7. A method for inverting the medium distribution of intermittent flow in a horizontal gas well and calculating the water holdup, as described in claim 6, characterized in that Based on the gas-liquid arc interface equation, the water holdup of the grid is assigned by using the interpolation method, and the water holdup imaging map of the wellbore cross-section is completed, which specifically includes: Based on the gas-liquid arc interface equation, all the horizontal and vertical coordinates and the corresponding water holdup values on the maximum arc interface and the median arc interface of the mixed fluid region are obtained. For each abscissa from left to right, quadratic linear interpolation is performed in the corresponding radial direction, that is, the water holdup of each grid can be assigned. The water holdup calculation formula for any point N on the wellbore cross-section is: If Y N > 1, then assign the value 1, that is, Y N = 1; If Y N < 0, then assign the value 0, that is, Y N = 0; Y N is the water holdup value at any point N of the wellbore cross-section, in decimals; Based on the obtained water holdup corresponding to the grid, color mapping is performed to complete the water holdup imaging map of the wellbore cross-section.

8. A method for inverting the medium distribution of intermittent flow in a horizontal gas well and calculating the water holdup, as described in claim 6, characterized in that Using the maximum and minimum coordinate values of the gas-liquid mixed fluid region on both sides of the wellbore circumference and on the central vertical line of the wellbore, an ellipse is constructed where the gas-liquid arc interface intersects the wellbore at three points. The upper part of the intersection of the ellipse and the wellbore is the gas section, and the lower part is the liquid section, which specifically includes: Define the maximum and minimum points of the gas-liquid mixed fluid region on the vertical line of the wellbore center as {C min , C max}, and the maximum and minimum points of the gas-liquid mixed fluid region on both sides of the wellbore circumference as {A min , A max ; B min , B max}; The standard elliptic rectangular coordinate equations corresponding to the maximum gas plug arc interface and the minimum gas plug arc interface are respectively: It is considered that the upper part of the intersection of the ellipse and the wellbore is the gas section, and the lower part is the liquid section. An inscribed circle of the ellipse is made with the major axis of the ellipse as the radius. Then, the area of the intersection part of the ellipse and the wellbore is calculated according to the local sector area of the inscribed circle. The relationship between the ellipse and its inscribed circle is as follows: The radial included angle ranges from A min / A max , C min / C max and is obtained from the positional relationship as follows: Among them, a min , b min , a max , b max are the major and minor semi-axes of the ellipse corresponding to the maximum arc air plug and the minimum arc air plug, respectively, m.

9. A method for inverting the medium distribution of intermittent flow in a horizontal gas well and calculating the water holdup rate according to claim 8, characterized in that, Based on the constructed ellipse, the difference between the maximum liquid section area and the minimum liquid section area is obtained to get the area of the gas-liquid mixed fluid region, and then the average water holdup of the wellbore cross-section is calculated, which specifically includes: Based on the positional relationship among the ellipse, the circumscribed circle and the shaft, and the ordinate of point C min / C max Establish an equation related to the major semi-axis of the ellipse and establish a system of equations: Solve the equation to obtain the major and minor semi-axes a min , b min , a max , b max , then the maximum liquid segment area and the minimum liquid segment area are respectively: The difference between the two areas is the area of the mixed fluid region: A M = A L,min -A L,max Then the water holdup of the liquid film section is: Among them, are respectively A min , B min , A max , B max the intersection points of the horizontal extension lines and the circumscribed circle; is the ellipse and the center of its circumscribed circle; are respectively triangles the area of, m 2 ; |A min C min |, |A min，x C min,x |, |A min,y C min,y |(A max C max |, |A max,x C max,x |, |A max,y C max,y |) are the distances from points A min , C min , A max , C max to the horizontal distance and the vertical distance, m; θ 0,min is B min , C min is the included angle between the connecting line of points B and C and the central vertical line, °; θ 0,max is B max , C max the included angle between the connecting line of points B and C and the central perpendicular line, °; θ 1,min The included angle, in °, between the perpendicular line from the center of the wellbore to point B min and the central perpendicular line; θ 1,max is the included angle, in °, between the perpendicular line from the wellbore center to point B max and the central perpendicular line; θ 2,min is the included angle between the perpendicular line from the midpoint of the ellipse to the point and the perpendicular line from the center, °; θ 2,max is the angle between the perpendicular from the midpoint of the ellipse to a point and the central perpendicular, °; ​ A L,min and A L,max are the maximum liquid cross-sectional area and the minimum liquid cross-sectional area of the wellbore, respectively, in m 2 ; A t is the cross-sectional area of the wellbore, m 2 ; Y M It is the hold-up of the mixed fluid region, expressed as the weighted average of the probe hold-up in the mixed fluid region, in decimals; Y w is the water holdup of the intermittent flow liquid film section, in decimals.

10. A system for inverting the distribution of intermittent flow media and calculating the water holdup in a horizontal gas well, characterized in that, The system includes: A measurement module, which is used to detect and obtain the response values of each probe of the array water holdup meter in the fluid of the horizontal wellbore and perform normalization processing; A coordinate system construction module, which is used to establish a coordinate system for the horizontal wellbore cross-section with the center of the horizontal wellbore as the origin, the horizontal direction as the x-axis direction, and the vertical direction as the y-axis direction, obtain the position coordinates of each probe, and perform grid division on the horizontal wellbore cross-section based on the established coordinate system; A mixed fluid region determination module, which is used to project each probe onto the vertical y-axis, and successively judge the difference between the normalized values of the responses of two adjacent probes from top to bottom according to the projection positions. The two adjacent probes corresponding to the obtained minimum value are determined to be located in the gas-liquid mixed fluid region, and the maximum, minimum and median coordinates of the gas-liquid mixed fluid region on both sides of the wellbore circumference are obtained; A gas-liquid interface lowest point determination module, which is used to, based on the determined gas-liquid mixed fluid region, use the wet-wall perimeter and the chord length corresponding to the wet-wall fraction, introduce a constraint factor, establish an equation to obtain the arch height of the part surrounded by the gas-liquid arc interface to be obtained and the chord length corresponding to the wet-wall fraction, and obtain the maximum, minimum and median coordinates of the gas-liquid mixed fluid region on the central vertical line of the wellbore; The interface interpolation and extension module is used to invert the interface interpolation and extension algorithm based on the intermittent flow medium distribution. According to the maximum and minimum values and the median coordinates of the gas-liquid mixed fluid region on both sides of the wellbore circumference and on the vertical line of the wellbore center, and combined with linear interpolation, the gas-liquid arc interface equation of the maximum and minimum values and the median of the gas-liquid mixed fluid region is obtained. Based on the gas-liquid arc interface equation and using the interpolation method, the water holdup is assigned to the grid, and the water holdup imaging map of the wellbore cross-section is completed; The circle-ellipse model construction module is used to construct an ellipse where the gas-liquid arc interface intersects the wellbore at three points by using the maximum and minimum value coordinates of the gas-liquid mixed fluid region on both sides of the wellbore circumference and on the vertical line of the wellbore center. The upper part of the intersection of the ellipse and the wellbore is the gas section, and the lower part is the liquid section. Based on the constructed ellipse, the difference between the maximum liquid section area and the minimum liquid section area is obtained to get the area of the gas-liquid mixed fluid region, and then the average water holdup of the wellbore cross-section is calculated.

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