CN110929458B - Annulus comprehensive hydraulic equivalent diameter calculation method for irregular well bore section - Google Patents
Annulus comprehensive hydraulic equivalent diameter calculation method for irregular well bore section Download PDFInfo
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Abstract
The invention discloses a method for calculating annulus comprehensive hydraulic equivalent diameter aiming at an irregular well bore section, which comprises the steps of obtaining well diameter series data and drilling data; calculating the axial length of the irregular well bore section, the length of the well wall curve section and the ratio of the axial length to the length of the well wall curve section; monitoring to obtain the sum of the flow pressure drops inside and outside the pipe of the irregular well section; presetting an annular hydraulic equivalent diameter, and calculating the sum of flow pressure drops inside and outside the corresponding pipe; and comparing the calculated and monitored flow pressure drops, adding or subtracting a preset small value to or from the preset annular hydraulic equivalent diameter when the difference is not smaller than the preset minimum difference, adopting an iterative calculation method to enable the difference to be smaller than the preset minimum difference, and taking the annular hydraulic equivalent diameter when the difference is smaller than the preset minimum difference as the calculated annular comprehensive hydraulic equivalent diameter. The method can quickly and conveniently determine the annular comprehensive hydraulic equivalent diameter of the irregular well bore section, improves the calculation performance and convenience of the annular flow pressure drop, and further can accurately and conveniently calculate the annular pressure.
Description
Technical Field
The invention relates to the technical field of well cementation in drilling engineering, in particular to a method for calculating the annular comprehensive hydraulic equivalent diameter of an irregular well bore section.
Background
Because of the influence of formation heterogeneity, formations with different depths often have different degrees of hole expansion, and irregular or 'sugar-hoist' -shaped irregular wellbores are extremely easy to form. Such irregular wellbores do not facilitate the determination of the annulus hydraulic equivalent diameter, directly affecting the annulus flow pressure drop calculation. At present, when the annulus flow pressure drop is calculated, the annulus is assumed to be a regular smooth straight borehole, and the annulus pressure is not calculated accurately due to the fact that the annulus pressure is not matched with the actual working condition. There is thus a need for improvements and improvements in the art.
Disclosure of Invention
In view of the shortcomings of the prior art, the invention aims to provide a method for calculating the annular comprehensive hydraulic equivalent diameter of an irregular well bore section, which can conveniently determine the annular comprehensive hydraulic equivalent diameter of the irregular well bore section and improve the accuracy and convenience of annular flow pressure drop calculation.
In order to achieve the above purpose, the invention adopts the following technical scheme:
an annular comprehensive hydraulic equivalent diameter calculation method of an irregular well bore section comprises the following steps:
acquiring well diameter series data of all measuring points in an irregular well bore section selected from a well diameter curve chart and drilling data;
drawing an irregular borehole diameter curve graph according to the borehole diameter series data of the selected irregular borehole section, and calculating the axial length of the irregular borehole section, the length of the borehole wall curve section and the ratio of the axial length to the length of the borehole wall curve section;
obtaining wellhead pressure P of casing shoes respectively at top depths and bottom depths of irregular well bore sections from casing running records by using drilling fluid circulation displacement Q 1 And P 2 And calculating the sum delta P of the internal and external flow pressure drops of the irregular well bore section 1 ；
Presetting an annular hydraulic equivalent diameter, and calculating the sum delta P of flow pressure drops inside and outside a pipe when the preset annular hydraulic equivalent diameter circulates at the discharge rate Q of the drilling fluid according to a drilling fluid flow pressure drop calculation formula 2 ；
Comparing the monitored sum DeltaP of the pressure drop of the flow inside and outside the pipe 1 Sum DeltaP of flow pressure drop inside and outside the pipe corresponding to preset annular hydraulic equivalent diameter 2 ；
When DeltaP 1 And DeltaP 2 When the difference value of the hydraulic equivalent diameter is not smaller than the preset minimum difference value, adding or subtracting a preset small value to the preset hydraulic equivalent diameter of the annulus to form a new hydraulic equivalent diameter of the annulusCalculating new sum of internal and external flow pressure drops of the pipe, and repeatedly and iteratively calculating until delta P 1 And DeltaP 2 And when the difference value of the annular hydraulic equivalent diameter is smaller than a preset value, the final annular hydraulic equivalent diameter is taken as the calculated annular comprehensive hydraulic equivalent diameter.
Compared with the prior art, the annular space comprehensive hydraulic equivalent diameter calculation method of the irregular well bore section comprises the steps of obtaining well diameter series data and drilling data; calculating the axial length of the irregular well bore section, the length of the well wall curve section and the ratio of the axial length to the length of the well wall curve section; calculating the sum of the flow pressure drops inside and outside the pipe of the monitored irregular wellbore section; presetting an annular hydraulic equivalent diameter, and calculating the sum of flow pressure drops inside and outside the corresponding pipe; and comparing the calculated and monitored flow pressure drops, adding or subtracting a preset small value to or from the preset annular hydraulic equivalent diameter when the difference is not smaller than the preset minimum difference, adopting an iterative calculation method to enable the difference to be smaller than the preset minimum difference, and taking the annular hydraulic equivalent diameter when the difference is smaller than the preset minimum difference as the calculated annular comprehensive hydraulic equivalent diameter. The method can conveniently and rapidly determine the annular comprehensive hydraulic equivalent diameter of the irregular well bore section, improves the accuracy and convenience of annular flow pressure drop calculation, and further can accurately and conveniently calculate the annular pressure.
Drawings
FIG. 1 is a flow chart of a preferred embodiment of a method for calculating the annular composite hydraulic equivalent diameter of an irregular wellbore section according to the present invention;
FIG. 2 is a flow chart of a preferred embodiment of the step S400 in the method for calculating the annular composite hydraulic equivalent diameter of an irregular wellbore section according to the present invention.
Detailed Description
In view of the defects that the annulus hydraulic equivalent diameter cannot be accurately determined, the annulus flow pressure drop calculation is affected, and the like in the prior art, the invention provides the annulus comprehensive hydraulic equivalent diameter calculation method for the irregular well bore section, which can conveniently and rapidly determine the annulus comprehensive hydraulic equivalent diameter of the irregular well bore section, and improves the accuracy and convenience of the annulus flow pressure drop calculation.
In order to make the objects, technical solutions and effects of the present invention clearer and more specific, the present invention will be described in further detail below with reference to the accompanying drawings and examples. It should be understood that the specific embodiments described herein are for purposes of illustration only and are not intended to limit the scope of the invention.
Referring to fig. 1, a flowchart of a method for calculating an annulus integrated hydraulic equivalent diameter of an irregular wellbore section according to a preferred embodiment of the present invention includes the following steps:
s100, acquiring well diameter series data of all measuring points in the irregular well bore section selected from the well diameter curve chart and drilling data.
In this embodiment, the irregular wellbore section may be a "large belly" wellbore section, a "sugarcoated haws" wellbore section, etc., and for convenience of description, the "large belly" wellbore section will be described below, but it should be understood that the irregular wellbore section according to the present invention is not limited to the "large belly" wellbore section, and the wellbore diameter series data at least includes the measuring point depth H j And measuring point well diameter D j Wherein j is a natural number from 1 to m, and m is the number of logging points of the irregular wellbore section; the drilling data includes at least a casing outer diameter D o Inner diameter D of sleeve i Drilling fluid density ρ, drilling fluid circulation displacement Q, drilling fluid fluidity index n, and drilling fluid consistency coefficient k.
And S200, drawing an irregular borehole diameter curve graph according to borehole diameter series data of the selected irregular borehole section, and calculating the axial length of the irregular borehole section, the length of the borehole wall curve section and the ratio of the axial length to the length of the borehole wall curve section.
In this embodiment, the calculation formula of the axial length is: l (L) 1 ＝H m -H 1 Wherein H is m Depth of the mth measuring point, H 1 Depth of 1 st measuring point, L 1 Is an axial length; the calculation formula of the length of the well wall curve segment is as follows:wherein D is j+1 The diameter of the well at the j+1th measuring point, D j The diameter of the well is the j-th measuring point, H j+1 For the depth of the j+1th measurement point,H j depth of the j-th measuring point L 2 The length of the curve section of the well wall; the calculation formula of the ratio of the axial length to the length of the curve section of the well wall is as follows: η=l 1 /L 2 Where η is the ratio of the axial length to the length of the curved section of the borehole wall.
S300, acquiring wellhead pressure P when casing shoes are respectively placed in the top depth and the bottom depth of an irregular well section and circulated by drilling fluid displacement Q from casing running construction records 1 And P 2 And calculating the sum delta P of the internal and external flow pressure drops of the irregular well bore section 1 。
In the embodiment, taking a "big belly" well section as an example, in the process of casing running, a casing shoe is placed at the top deep of the "big belly" well section, and the wellhead pressure P is recorded by circulating the drilling fluid displacement Q in the drilling construction record 1 The method comprises the steps of carrying out a first treatment on the surface of the Then the sleeve shoes are placed in the deep bottom of the 'big belly' well hole section, circulation is carried out by using the drilling fluid discharge Q in the drilling construction record, and the wellhead pressure P is recorded 2 The method comprises the steps of carrying out a first treatment on the surface of the The sum of the monitored pressure drop of the flow inside and outside the tube of the "big belly" well section is DeltaP 1 ＝P 2 -P 1 。
S400, presetting an annular hydraulic equivalent diameter, and calculating the sum delta P of flow pressure drops inside and outside a pipe corresponding to the preset annular hydraulic equivalent diameter through a drilling fluid flow friction pressure drop calculation formula 2 。
In this embodiment, according to the calculation formula of the annular flow pressure drop, the annular hydraulic equivalent diameters are different, and the corresponding annular fluid friction coefficients are also different, so that the corresponding annular flow pressure drops are also different. The present invention therefore first assumes an annular hydraulic equivalent diameter D h The sum of the flow pressure drops inside and outside the tube is calculated, and the specific flowchart of the step S400 is shown in fig. 2.
Please refer to fig. 2, which is a flowchart of the step S400, comprising the steps of:
s401, presetting an annular hydraulic equivalent diameter, and calculating the annular flow velocity of drilling fluid and the reynolds number of the drilling fluid corresponding to the preset annular hydraulic equivalent diameter;
s402, calculating the flow friction coefficient of the drilling fluid according to the calculated Reynolds number of the drilling fluid;
s403, calculating the sum delta P of flow pressure drops inside and outside the pipe when the preset annular hydraulic equivalent diameter corresponds to the circulation of the drilling fluid with the discharge capacity Q according to the drilling fluid flow friction coefficient and the drilling data 2 。
Specifically, in S401, the flow velocity V in the drilling fluid pipe is calculated i And annulus flow velocity V o Respectively corresponding drilling fluid pipe flow Reynolds number Re PLi And the annular flow Reynolds number Re of drilling fluid PLo Specifically, the following table shows:
further, in the step S402, when calculating the flow friction coefficient of the drilling fluid, it is necessary to determine the flow state of the drilling fluid, and then calculate according to the corresponding formula, where the method for determining the flow state of the drilling fluid is as follows:
| flow state | Pipe flow | Annular flow |
| Laminar flow | Re PLi ≤Re PL1 | Re PLo ≤Re PL1 |
| Transitional flow | Re PL1 ＜Re PLi ＜Re PL2 | Re PL1 ＜Re PLo ＜Re PL2 |
| Turbulence flow | Re PLi ≥Re PL2 | Re PLo ≥Re PL2 |
Wherein Re is PL1 Represents the upper critical Reynolds number, re PL2 Represents the lower critical Reynolds number, re, and the upper critical Reynolds number PL1 The calculation formula of (2) is as follows: re (Re) PL1 The calculation formula of the lower critical reynolds number=3250-1150×n is: re (Re) PL2 =4150-1150×n, where n represents the drilling fluid fluidity index; after judging the flow state of the drilling fluid, the calculation of the friction coefficient of the laminar flow state can be carried out through the following table:
when the flow regime is turbulent, the flow friction coefficient can be calculated by the following empirical formula, regardless of the geometry in which the fluid flows:wherein the constants a, B can be determined from the power law index (drilling fluid fluidity index) n, as shown in the following table. If n is not found in the table, a, B can be determined by linear interpolation.
| n | A | B |
| 0.2 | 0.0646 | 0.349 |
| 0.3 | 0.0685 | 0.325 |
| 0.4 | 0.0712 | 0.307 |
| 0.6 | 0.074 | 0.281 |
| 0.8 | 0.076 | 0.263 |
| 1.0 | 0.0779 | 0.250 |
When the flow state is transition flow and the friction coefficient is calculated, the friction coefficient when the Reynolds number is equal to the lower critical Reynolds number can be calculated according to the laminar flow state, the friction coefficient when the Reynolds number is equal to the upper Reynolds number is calculated according to the turbulent flow state, and finally linear interpolation is carried out according to the actual Reynolds number.
In step S403, the drilling fluid flow friction pressure drop calculation formula is:
wherein, the liquid crystal display device comprises a liquid crystal display device,
D h is the annular hydraulic equivalent diameter, f i For the friction coefficient, V, of the flow in the drilling fluid pipe i For the flow rate in the drilling fluid pipe, f o For the annulus flow friction coefficient of the drilling fluid, V o Is the annular flow rate of drilling fluid.
Therefore, the sum of the flow pressure drop inside and outside the pipe corresponding to the preset annular hydraulic equivalent diameter can be obtained by substituting the preset annular hydraulic equivalent diameter into the formulas.
S500, comparing the sum delta P of the monitored flow pressure drops inside and outside the pipe 1 Sum DeltaP of flow pressure drop inside and outside the pipe corresponding to preset annular hydraulic equivalent diameter 2 ；
S600, when delta P 1 And DeltaP 2 When the difference value of the flow pressure difference is not smaller than the preset minimum difference value, adding or subtracting a preset small value to the preset annular hydraulic equivalent diameter, forming a new annular hydraulic equivalent diameter, calculating the new sum of the flow pressure drops inside and outside the pipe, and repeatedly and iteratively calculating until delta P is reached 1 And DeltaP 2 And when the difference value of the annular hydraulic equivalent diameter is smaller than a preset value, the final annular hydraulic equivalent diameter is taken as the calculated annular comprehensive hydraulic equivalent diameter.
In this embodiment, the step S600 specifically includes:
when DeltaP 1 <△P 2 When the method is used, a preset small value is added to the preset annular hydraulic equivalent diameter to form a new annular hydraulic equivalent diameter, the new annular hydraulic equivalent diameter is substituted into a drilling fluid flow friction pressure drop calculation formula to calculate the sum of new flow pressure drops inside and outside the pipe, and iterative calculation is repeated until the value delta P is equal to the value delta P 1 -△P 2 |<At 0.01, will be |ΔP 1 -△P 2 |<The annular hydraulic equivalent diameter at 0.01 is taken as the required annular hydraulic equivalent diameter; when DeltaP 1 >△P 2 When the method is used, a preset small value is subtracted from the preset annular hydraulic equivalent diameter to form a new annular hydraulic equivalent diameter, the new annular hydraulic equivalent diameter is substituted into a drilling fluid flow friction pressure drop calculation formula to calculate the sum of new flow pressure drops inside and outside the pipe, and iterative calculation is repeated until the value delta P is equal to the value delta P 1 -△P 2 |<At 0.01, will be |ΔP 1 -△P 2 |<The annulus hydraulic equivalent diameter at 0.01 was used as the calculated annulus integrated hydraulic equivalent diameter.
Specifically, the sum ΔP of the monitored flow pressure drops inside and outside the tube is compared 1 And the calculated sum DeltaP of the flow pressure drop inside and outside the tube 2 After that, if DeltaP 1 <△P 2 Then at the assumed annular hydraulic equivalent diameter D h Adding a small value epsilon on the basis to ensure that the new annular hydraulic equivalent diameter D hc Substituting the formula of the step S400 to calculate, and repeatedly iterating until the value is delta P 1 -△P 2 |<0.01, assuming D at this time hc The final annulus comprehensive hydraulic equivalent diameter is obtained; if DeltaP 1 >△P 2 Then in the assumption of annulus hydraulic equivalent diameter D h Subtracting a small value epsilon on the basis to obtain a new annular hydraulic equivalent diameter D hc Substituting the formula of the step S400 to calculate, and repeating the fating iteration until the I delta P is obtained 1 -△P 2 |<0.01, assuming D at this time hc The final annular comprehensive hydraulic equivalent diameter is the final DeltaP 1 And DeltaP 2 The difference value of the annular hydraulic equivalent diameter is extremely small, so that the calculated annular hydraulic equivalent diameter has extremely small deviation from an actual result and high accuracy.
Preferably, the method for calculating the annular comprehensive hydraulic equivalent diameter of the irregular well bore section further comprises the following steps:
and drawing a change curve of the annular comprehensive hydraulic equivalent diameter along with the ratio of the axial length to the length of the well wall curve section, and forming a relation table of the annular comprehensive hydraulic equivalent diameter and the ratio of the axial length to the length of the well wall curve section.
Specifically, in order to facilitate subsequent engineering application, after calculating the ratio of a plurality of axial lengths to the lengths of the curve sections of the well wall and the corresponding annular comprehensive hydraulic equivalent diameters, a corresponding change curve chart and a corresponding relation table are drawn, and in the subsequent application, the corresponding annular comprehensive hydraulic equivalent diameters can be directly found according to the chart, so that the method is convenient and quick.
In a preferred embodiment, the method for calculating the annulus comprehensive hydraulic equivalent diameter of the irregular wellbore section further comprises the following steps:
and calculating the internal and external flow pressure drop of the regular borehole section unit under the unit length when the drilling fluid displacement Q circulates, and calculating the comprehensive conversion coefficient of the internal and external flow pressure drop of the irregular borehole section corresponding to the ratio of the axial length to the length of the borehole wall curve section under the condition of the same circulating displacement.
In the embodiment, in the process of casing running, a casing shoe is placed at the top depth L3 of a regular well hole section (without expanding), drilling fluid is circulated by the displacement Q, and the vertical pressure P3 of a well mouth is recorded; and then placing the casing shoe at the bottom depth L4 of the regular well section, circulating drilling fluid with a displacement Q, recording vertical pressure P4 at a wellhead, wherein the pressure drop of the flow inside and outside the pipe under the unit length of the regular well section is (P4-P3)/(L4-L3), so that under the condition of the same circulating displacement, the ratio eta of the axial length to the length of the well wall curve section corresponds to the comprehensive conversion coefficient lambda= (P2-P1) (L4-L3)/L (P4-P3) of the pressure drop of the flow inside and outside the pipe of the irregular well section relative to the pressure drop of the flow inside and outside the pipe of the regular well section with the same axial length, and then sequentially analogizing according to the calculation method, thereby obtaining the comprehensive conversion coefficient of the flow pressure drop inside and outside the pipe of the irregular well section corresponding to different eta values, and providing a reference for quickly calculating the flow pressure drop inside and outside the pipe of the irregular well section.
For ease of understanding, the following description will be given with reference to one specific example:
step one: obtaining an external diameter value D of a production casing of a certain well of a land oil field o =0.1397 m, inner diameter D of cannula i The method comprises the steps of (1) selecting a certain 'large belly' well section from a well diameter graph, and obtaining depth and well diameter data series of all measuring points in the section, wherein the depth and well diameter data series are shown in table 1; simultaneously obtaining drilling fluid density value rho=1140 kg/m 3 Drilling fluid circulation discharge value q=0.03m 3 Drilling fluid fluidity index n=0.856, drilling fluid consistency coefficient k=0.145 pa·s n 。
Step two: the axial length L= 1002.8-1001=1.8m of the "big belly" well section is calculated, the length of the well wall curve section is 1.80695m, and the ratio eta= 0.99615 of the axial length to the length of the well wall curve section.
Step three: in the process of casing running, a casing shoe is arranged at the top depth (1001 m) of a 'large belly' well section, the drilling fluid is circulated at the discharge capacity Q=30L/s, and the vertical pressure P of a wellhead is recorded 1 = 10.162MPa; then the sleeve shoe is placed at the bottom depth (1010 m) of the 'large belly' well section, the drilling fluid is circulated at the discharge capacity Q=30L/s, and the vertical pressure P of the well mouth is recorded 2 =10.18 MPa; the pressure drop of the internal and external circulation of the pipe with the 'big belly' well hole section is delta P 1 ＝0.018MPa。
Step four: assuming an annulus hydraulic equivalent diameter D h = 0.2159m, calculating the sum Δp of the intra-and-inter flow pressure drops of the "large belly" wellbore section in step four 2 =0.025 MPa, and the final annular comprehensive hydraulic equivalent diameter D is obtained by iterative calculation hc = 0.2382m. And by analogy with the calculation method, the annular comprehensive hydraulic equivalent diameters corresponding to different eta values can be obtained, so that references are provided for other wells.
Step five: in the process of casing running, placing a casing shoe at the top depth L3=1005 m of a regular well bore section, circulating drilling fluid at the discharge capacity Q=30L/s, and recording the vertical pressure P3=10.2 MPa of a wellhead; and then placing the casing shoe at the bottom depth L4=1010 m of the regular well section, circulating drilling fluid with the displacement Q=30L/s, recording the vertical pressure P4=10.27 MPa of the wellhead, wherein the pressure drop of the flow inside and outside the pipe under the unit length of the regular well section is 0.014MPa/m, so that under the condition of the same circulating displacement, the ratio eta of the axial length to the length of the well wall curve section corresponds to the comprehensive conversion coefficient lambda=0.7143 of the pressure drop of the flow inside and outside the pipe of the irregular well section relative to the pressure drop of the flow inside and outside the pipe of the regular well section with the same axial length, and analogizing sequentially according to the calculation method, thereby obtaining the comprehensive conversion coefficient of the flow pressure drop inside and outside the pipe of the irregular well section corresponding to different eta values, and providing a reference for rapidly calculating the flow pressure drop inside and outside the pipe of the irregular well section.
It should be understood that, although the steps in the flowcharts of fig. 1 and 2 are shown in order as indicated by the arrows, these steps are not necessarily performed in order as indicated by the arrows. The steps are not strictly limited to the order of execution unless explicitly recited herein, and the steps may be executed in other orders.
In summary, the method and the device can conveniently determine the annular comprehensive hydraulic equivalent diameter of the irregular well bore section, improve the accuracy of annular flow pressure drop calculation, and further accurately calculate the annular pressure.
It will be understood that equivalents and modifications will occur to those skilled in the art in light of the present invention and their spirit, and all such modifications and substitutions are intended to be included within the scope of the present invention as defined in the following claims.
Claims (10)
1. The method for calculating the annular comprehensive hydraulic equivalent diameter of the irregular well bore section is characterized by comprising the following steps of:
acquiring well diameter series data of all measuring points in an irregular well bore section selected from a well diameter curve chart and drilling data;
drawing an irregular borehole diameter curve graph according to the borehole diameter series data of the selected irregular borehole section, and calculating the axial length of the irregular borehole section, the length of the borehole wall curve section and the ratio of the axial length to the length of the borehole wall curve section;
obtaining wellhead pressure P when casing shoes are respectively positioned at the top depth and the bottom depth of an irregular well section and circulated at drilling fluid displacement Q from casing running records 1 And P 2 And calculating the sum delta P of the internal and external flow pressure drops of the monitored irregular wellbore section pipe 1 ；
Presetting an annular hydraulic equivalent diameter, and calculating the sum delta P of the internal and external flow pressure drops of the pipe when the preset annular hydraulic equivalent diameter corresponds to circulation with the drilling fluid displacement Q through a drilling fluid flow pressure drop calculation formula 2 ；
Comparing the monitored sum DeltaP of the pressure drop of the flow inside and outside the pipe 1 The sum delta P of the flow pressure drop inside and outside the pipe corresponding to the preset annular hydraulic equivalent diameter 2 ；
When DeltaP 1 And DeltaP 2 When the difference value of the two flow pressure drops is not smaller than the preset minimum value, adding or subtracting a preset small value to the preset annular hydraulic equivalent diameter to form a new annular hydraulic equivalent diameter, calculating the new sum of the flow pressure drops inside and outside the pipe, and repeatedly and iteratively calculating until delta P is reached 1 And DeltaP 2 And when the difference value of the annular hydraulic equivalent diameter is smaller than a preset value, the final annular hydraulic equivalent diameter is taken as the calculated annular comprehensive hydraulic equivalent diameter.
2. The method for calculating the comprehensive hydraulic equivalent diameter of an irregular section of a well annulus according to claim 1, wherein the well diameter series data at least comprises a measuring point depth H j And measuring point well diameter D j Wherein j is a natural number from 1 to m, and m is the number of logging points of the irregular wellbore section; the drilling data includes at least a casing outer diameter D o Inner diameter D of sleeve i Drilling fluid density ρ, drilling fluid circulation displacement Q, drilling fluid fluidity index n, and drilling fluid consistency coefficient k.
3. The method for calculating the annular comprehensive hydraulic equivalent diameter of an irregular wellbore section according to claim 2, wherein the calculation formula of the axial length is:
L 1 ＝H m -H 1 ，
wherein H is m Depth of the mth measuring point, H 1 Depth of 1 st measuring point, L 1 Is the axial length.
4. The method for calculating the annular comprehensive hydraulic equivalent diameter of an irregular wellbore section according to claim 3, wherein the calculation formula of the length of the wellbore wall curve section is as follows:
wherein D is j+1 The diameter of the well at the j+1th measuring point, D j The diameter of the well is the j-th measuring point, H j+1 Depth of the j+1th measuring point, H j For the j-th measuring pointDepth, L 2 Is the length of the curve section of the well wall.
5. The method for calculating the annular comprehensive hydraulic equivalent diameter of an irregular wellbore section according to claim 4, wherein the calculation formula of the ratio of the axial length to the length of the curve section of the well wall is:
η＝L 1 /L 2 where η is the ratio of the axial length to the length of the curved section of the borehole wall.
6. The method of calculating the annular composite hydraulic equivalent diameter of an irregular section of wellbore of claim 5, wherein the sum of monitored internal and external flow pressure drops Δp of the irregular section of wellbore 1 The calculation formula of (2) is as follows: deltaP 1 ＝P 2 -P 1 。
7. The method for calculating the annular comprehensive hydraulic equivalent diameter of an irregular wellbore section according to claim 6, wherein the preset annular hydraulic equivalent diameter is calculated by a drilling fluid flow pressure drop calculation formula to obtain the sum DeltaP of the flow pressure drops inside and outside the pipe corresponding to the preset annular hydraulic equivalent diameter 2 The method comprises the following steps:
presetting an annular hydraulic equivalent diameter, and calculating the annular flow rate of drilling fluid and the reynolds number of the drilling fluid corresponding to the preset annular hydraulic equivalent diameter;
calculating the flow friction coefficient of the drilling fluid according to the calculated Reynolds number of the drilling fluid;
calculating the sum delta P of the flow pressure drop inside and outside the pipe corresponding to the preset annular hydraulic equivalent diameter according to the flow friction coefficient of the drilling fluid and the drilling data 2 。
8. The method for calculating the annular comprehensive hydraulic equivalent diameter of an irregular wellbore section according to claim 7, wherein the drilling fluid flow friction pressure drop calculation formula is:
wherein D is h Is the annular hydraulic equivalent diameter, f i For the friction coefficient, V, of the flow in the drilling fluid pipe i For the flow rate in the drilling fluid pipe, f o For the annulus flow friction coefficient of the drilling fluid, V o Is the annular flow rate of drilling fluid.
9. The method of calculating an annular hydraulic equivalent diameter of an irregular section of a wellbore of claim 8, wherein the equivalent Δp 1 And DeltaP 2 When the difference value of the flow pressure difference is not smaller than the preset minimum difference value, adding or subtracting a preset small value to the preset annular hydraulic equivalent diameter, forming a new annular hydraulic equivalent diameter, calculating the new sum of the flow pressure drops inside and outside the pipe, and repeatedly and iteratively calculating until delta P is reached 1 And DeltaP 2 The step of using the final annular hydraulic equivalent diameter as the calculated annular comprehensive hydraulic equivalent diameter when the difference value of (2) is smaller than the preset value is specifically as follows:
when DeltaP 1 <△P 2 When the method is used, a preset small value is added to the preset annular hydraulic equivalent diameter to form a new annular hydraulic equivalent diameter, the new annular hydraulic equivalent diameter is substituted into a drilling fluid flow friction pressure drop calculation formula to calculate the sum of new flow pressure drops inside and outside the pipe, and iterative calculation is repeated until the value delta P is equal to the value delta P 1 -△P 2 |<At 0.01, will be |ΔP 1 -△P 2 |<The annulus hydraulic equivalent diameter at 0.01 is taken as the calculated annulus comprehensive hydraulic equivalent diameter; when DeltaP 1 >△P 2 When the method is used, a preset small value is subtracted from the preset annular hydraulic equivalent diameter to form a new annular hydraulic equivalent diameter, the new annular hydraulic equivalent diameter is substituted into a drilling fluid flow friction pressure drop calculation formula to calculate the sum of new flow pressure drops inside and outside the pipe, and iterative calculation is repeated until the value delta P is equal to the value delta P 1 -△P 2 |<At 0.01, will be |ΔP 1 -△P 2 |<The annulus hydraulic equivalent diameter at 0.01 was used as the calculated annulus integrated hydraulic equivalent diameter.
10. The method of calculating an annular composite hydraulic equivalent diameter of an irregular section of a wellbore of claim 9, further comprising:
and drawing a change curve of the annular comprehensive hydraulic equivalent diameter along with the ratio of the axial length to the length of the well wall curve section, and forming a relation table of the annular comprehensive hydraulic equivalent diameter and the ratio of the axial length to the length of the well wall curve section.
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