A method for simulating a load

Abstract

The application discloses a kind of suspended weight simulation calculation method, by measuring the parameter of operation well and running casing, can quickly simulate and calculate the suspended weight of running casing, and in combination with the suspended weight data recorded in actual running process, can obtain suspended weight loss, for correcting simulation calculation.This method is suitable for long horizontal section casing completion, through theoretical calculation, ensure that casing can be run to specified design depth.The method solves the problem of long horizontal section casing completion, drilling continues to break through drilling depth, greatly saves the investment and time of owner, while realizing the maximization of drilling and completion benefit.The method is easy to understand and practical, makes petroleum operation more refined, guided by theoretical basis, improves operation success rate.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of oil and gas field development, and particularly relates to a suspended weight simulation calculation method. BACKGROUND

[0002] With the continuous development of technology, horizontal oil wells and gas wells are increasing, and the contradiction between the actual casing running depth and the drillable depth of the well is increasingly prominent. Therefore, how to smoothly run the casing to the specified depth has become the focus of many operators.

[0003] Under the prior art, there is a technical bottleneck in casing running. When running the casing, the axial component of the casing self weight and the liquid weight in the casing on the running trajectory is used to push the casing forward. When running the horizontal section, the component is very small or even zero (when the wellbore is upwarping, the component is negative). At the same time, the radial component of the casing self weight + liquid weight is getting larger and larger. The radial component produces frictional resistance, which leads to further reduction of the running suspended weight. In addition, the bending load, viscous resistance, irregular wellbore, well wall collapse, and drag of shale section further reduce the running suspended weight. When the wellhead suspended weight is reduced to zero during the running process, the casing cannot continue to run. At this time, the well must be completed. The subsequent production layer and productivity of drilling have to be lost.

[0004] The horizontal section friction is the main factor of the reduction of the suspended weight. For small hole and small casing, the operation is more challenging. When the casing is full of mud column, the radial component increases significantly. When the horizontal section friction increases to a certain extent, it will completely offset the axial component, resulting in stopping the casing before it reaches the depth. Moreover, other factors such as formation debris, drag effect and insufficient well flushing need to be considered. In order to ensure the smooth running of the casing to the horizontal section, a temporary barrier is usually installed to make the horizontal section casing full of air or low-density mud, which reduces the friction of the horizontal section and reduces the viscous resistance and torque drag. The running position of the floating collar determines the change of the wellhead suspended weight and the running depth of the casing. However, there is a lack of a method for theoretically calculating and simulating the wellhead suspended weight and determining the running position of the temporary barrier in the prior art. SUMMARY

[0005] The present application aims at the above-mentioned problems, and provides a suspended weight calculation method,

[0006] The technical content of the present application is as follows:

[0007] A suspended weight simulation calculation method, characterized in that it comprises the following steps:

[0008] Step 1: Obtain the parameters of the operation well and the running casing by measurement, including the length r and the equivalent weight m of the casing section to be calculated eq , the inclination angle θ and the path friction coefficient μ of the position of the casing section in the operation well;

[0009] Step 2: Obtain axial force F of the casing equivalent weight in the well section according to the parameters obtained in Step 1 a (r), the frictional resistance F generated by the casing during the running in the well section f (r) and the hanging loss F generated by the casing in the well section except for the frictional resistance L (r), the hanging load H is obtained according to the following calculation model hk (r):

[0010] H hk (r) = F a (r) - F f (r) - F L (r).

[0011] Further, in Step 2, the calculation model is specifically:

[0012]

[0013] Wherein, g is the acceleration of gravity.

[0014] Further, for the convenience of engineering calculation, the hanging load H of the entire casing n is calculated, the casing is divided into n sections, and θ and m between sections are eq the same or different, n sections are integrated and accumulated, and the following calculation model is used to solve:

[0015]

[0016] Wherein, S n is the total path length of the casing running in, F L (S n ) is the hanging loss in the Sn path.

[0017] Further, when the casing is in a position satisfying the following condition, i.e. reaching the HW zero point:

[0018] cosθ = μsinθ or

[0019] Wherein θ ∈ [0, π / 2].

[0020] Further, the determination steps of F L (S n ) are as follows:

[0021] Step 1: When the initial operation of the well in a certain block is simulated and calculated, F L (r) is 0, and the hanging load change curve of the casing running in the ideal state is obtained;

[0022] Step 2: During the casing running in the well operation, the actual hanging load change curve is obtained,

[0023] Step 3: The weight loss change graph under the path can be simulated by the difference between the ideal state weight change curve and the actual weight change curve, and then F L (S n ).

[0024] Further, the calculation method is suitable for weight simulation when one or more temporary barriers are added in the casing, the temporary barriers divide the casing into several parts, and the same or different medium is filled in the casing parts.

[0025] Further, the temporary barrier is a floating collar.

[0026] Further, the medium includes mud, water and air with different specific gravities.

[0027] Further, the calculation method is suitable for oil wells and gas wells.

[0028] Due to the above technical solutions, the application has the following advantages:

[0029] 1. The method is suitable for long horizontal section casing completion, and the casing can be lowered to the specified design depth through theoretical calculation. Since the method solves the problem of long horizontal section casing completion, drilling continues to break through the drilling depth, greatly saving the investment and time of the owner, and maximizing the drilling and completion efficiency.

[0030] 2. The method is easy to understand and practical, and makes the oil operation more refined. The method is guided by the theoretical basis to improve the operation success rate.

[0031] 3. The method provides a strong guarantee for long horizontal section casing completion. According to statistics, the productivity of many long horizontal extension horizontal wells is twice that of conventional completion. However, the investment of such long horizontal wells is about 1.5 times that of conventional wells. Therefore, each long horizontal section well can save half of the conventional investment. BRIEF DESCRIPTION OF DRAWINGS

[0032] Fig. 1 is a schematic diagram of an ideal state weight curve of a specific example; Figure 1 Fig. 2 is a comparison schematic diagram of weight curves under different states of a specific example;

[0033] Figure 2 Fig. 3 is a curve division schematic diagram of weight loss solution of a specific example.

[0034] Fig. 4 is a schematic diagram of a weight loss change graph under the path of a specific example. Figure 3 DETAILED DESCRIPTION

[0035] ​​All features disclosed in this specification, or steps in all methods or processes disclosed herein, may be combined in any way, except for mutually exclusive features and / or steps.

[0036] Any feature disclosed in this specification, unless otherwise stated, may be replaced by other equivalent or similar features. That is, unless otherwise stated, each feature is merely one example of a series of equivalent or similar features.

[0037] Example

[0038] A method for simulating and calculating suspended weight includes the following steps:

[0039] Step 1: Obtain parameters of the working well and the running casing by measurement, including the calculated length r and equivalent weight m of a certain section of the casing. eq The inclination angle θ and path friction coefficient μ of the casing section in the working well; relevant parameters of the working well can be obtained during the drilling process; the equivalent weight of the casing can be obtained by subtracting the buoyancy generated by the casing displacing the fluid in the well from the sum of the mass of the casing itself and the mass of the medium in the casing.

[0040] Step 2: Obtain the axial component F of the casing equivalent weight in the well section based on the parameters obtained in Step 1. a (r) Frictional resistance F generated during the casing's movement in the well section f (r) and the weight loss F of the casing in the well section, excluding frictional resistance. L (r), the suspended weight H is obtained according to the following calculation model. hk (r):

[0041] H hk (r)=F a (r)-F f (r)-F L (r).

[0042] Furthermore, in step 2, a stress analysis is performed on any segment of the sleeve, F a The formula for calculating (r) is F a (r)=g·m eq ·cosθ, where g is the acceleration due to gravity (the same applies below), F f The formula for calculating (r) is F f =μ·g·m eq ·sinθ,F L (r) represents losses during actual operation due to factors other than frictional resistance, including speed and bending force during operation, as well as torque and resistance caused by fluid adhesion. For ease of calculation, F is used when the casing has not reached the HW zero point. L(r) is approximately equal to 0. The definition of HW zero point is as follows: when the casing gradually expands in the vertical section during the running process, the hanging load of the casing will gradually increase during the running process for a certain section of the casing, and as the running process continues, until the frictional resistance is equal to the axial component of the equivalent weight of the casing, this critical point is defined as the HW zero point. The HW zero point can be obtained by cos θ = μ sin θ or When calculating θ, the HW zero point is the depth corresponding to the inclination angle. Obviously, the HW zero point is only related to the inclination angle and the friction coefficient. After the HW zero point, the amount of increase in the hanging load of the section continues to decrease, but this does not affect the basic model of the present application, and the same method can be used for calculation. In theory, the casing can be divided into several sections, and the medium inside each section of the casing can be the same or different. Due to the different positions in the well, the external environment of the casing is different, which may affect the equivalent mass, inclination angle and path friction coefficient, etc. Although the related parameters may change with the change of the path, however, in the actual drilling process, the obvious change of the parameters can also be obtained, which is the known quantity that drilling can provide. The related parameters are input into the edited excel formula or calculation software, and the calculation model is as follows:

[0043]

[0044] Therefore, it is convenient for engineering calculation, and the hanging load H n is calculated. The casing is divided into n sections, and θ and m eq between the sections are the same or different. The n sections are integrated and added, and the following calculation model is used to solve:

[0045]

[0046] Where S n is the total path length of the casing running, F L (S n ) is the hanging load loss under Sn path.

[0047] Further, in the foregoing, when F L (r) is not 0, F L (r) does not give the calculation method, however, F L (r) can be obtained according to the difference between the ideal hanging load calculation method and the actual hanging load. When the well in a certain block is initially operated for hanging load simulation calculation, F L (r) is not known, at this time we can assume that F L (r) is 0, and the ideal hanging load of the i-th section is ​We can draw the ideal state of casing under the suspension of the change curve; then we can put the casing into the actual operation of the casing, and obtain the actual suspension change curve in the process of casing downhole operation; finally, through the difference between the ideal state of the suspension change curve and the actual suspension change curve, the suspension loss change graph under the path can be simulated and calculated, and then F L (S n ).

[0048] The specific simulation calculation model is as follows: we assume, Where H c，i (r) is the theoretical simulation suspension of the suspension in the i-th section of the path r, H a，i (r) is the suspension in the actual working process of the suspension in the i-th section of the path r.

[0049] In order to solve the above equation, we list the following equation:

[0050]

[0051]

[0052]

[0053] c i =a i -b i i=1,2,…,N

[0054] Therefore, the suspension loss under the path r is:

[0055]

[0056] In fact, in the drilling and completion operation of a certain oilfield, most of the drilling and completion parameters change little. For the above equation, for the convenience of calculation, we can fit the suspension change curve into several straight line segments. For a straight line segment, a i and b i represent the slope of the segment in the theoretical simulation suspension and the actual suspension. Therefore, once the test is completed, a i can be calculated, b i can also be tested. c i is known. c i Will be applied to the subsequent suspension calculation. From the engineering point of view, it is more direct and accurate than setting data on the model.

[0057]

[0058] H a，i (r)=H c，i (r)-H L，i (r) (H-2)

[0059]

[0060] H-1, H-2, H-3 are analyzed, bi is calculated by well testing, ai can be calculated by (H-3), thus, ci = ai - bi will be determined. Once given ci, the hanging load H L,i (r) will be determined. Given H L,i (r), the actual hanging load is calculated by (H-2). The above equation can be easily modified into an Excel iterative equation, and the actual hanging load can be calculated by an engineer at home or in the office.

[0061] Further, the calculation method is applicable to the simulation of the hanging load when one or more temporary barriers are added in the casing, the temporary barriers divide the casing into several sections, and each section of the casing is filled with the same or different medium. Under the technical model of the scheme, when a float collar is run in, the float collar divides the casing into two sections, the section close to the bottom of the well is filled with air, which is beneficial to reduce the resistance of the casing running in, and the upper section of the float collar can be filled with other different medium, such as water or mud with different proportions, so as to increase the weight of the upper section and increase the hanging load, so as to ensure that the casing can be successfully run in. It has been mentioned in the background art that when the hanging load at the wellhead is reduced to zero during running in, the casing cannot continue to run in. At this time, only completion can be carried out, resulting in the loss of subsequent production layers and productivity of drilling. According to the calculation of the scheme, the running position of the float collar can be designed, so that the length and mass of the upper and lower sections of the casing divided by the float collar can be determined. Combined with the parameters of the operation well, we can simulate and calculate the hanging load under the condition of different length paths, and according to the hanging load value, it can be determined whether the casing can be run in to the corresponding path and the running depth. If the hanging load value cannot meet the safe operation, the hanging load can be simulated and calculated again by changing the running position of the float collar or changing the medium mass filled in the upper section of the casing divided by the float collar, until the running in condition is met. Finally, the accuracy and success rate of the casing running in are improved by a convenient method. If multiple temporary barriers are run in, the casing is divided into more sections, and different sections can select different counterweights.

[0062] Further, the temporary barrier includes but is not limited to the float collar, and can be other tools that have the "floating" function of the casing, as long as the casing can be divided, and different media can be filled in the divided sections, so that the casing close to the horizontal section reduces the resistance to forward progress, and the casing close to the wellhead section maintains sufficient running hanging load.

[0063] Further, the medium includes mud with different specific gravities, water and air, and different media can be configured in different sections according to needs.

[0064] Further, the calculation method is widely applicable to oil and gas wells.

[0065] Specifically, taking the casing running at a certain 5000m level as an example:

[0066] According to the casing deployment experience of HeH9-14 well, the horizontal well of HH90-3 well is planned to extend to 5060m. Similarly, two float collars are designed to be installed in the horizontal section. During the completion process, the casing running is carefully designed. The design criteria are as follows:

[0067] 1) The target HW zero point below is all air;

[0068] 2) When the casing horizontal extension length reaches 80%, the first float collar (NDS) will be installed. But the air will be filled up and down;

[0069] 3) When the casing reaches 100% horizontal extension, the second float collar (NDS) will be installed;

[0070] 4) If the casing hook weight is close to 40000N, mud will be found above the first float collar until the hook weight increases to 80000N;

[0071] 5) If the 100% horizontally extended casing is run in air, and the hook weight is not less than 40000N, the second float collar is installed, and mud is injected between every 2 float collars until the casing reaches the specified depth.

[0072] The specific design parameters are as follows:

[0073] Table 1

[0074]

[0075] Combined with the operation well parameters obtained during drilling operation, the following formula is used to solve:

[0076]

[0077] At this time F L (S n ) is 0, and the calculated hanging weight is as shown in Figure 1 , thereby simulating the hanging weight of the casing at different depths.

[0078] Using the above parameters for actual operation, the casing is successfully run in, and when the casing reaches the set depth, the surface hook weight still exceeds 166KN. The actual hanging weight change of the casing running in is shown as curve 2 in Figure 2 , and at the same time, according to the ideal state of the hanging weight change curve (curve 1 in Figure 2 ) and the actual hanging weight change curve (curve 2 in Figure 2The calculation parameters for curve 2) are obtained as shown in Table 2, and the corresponding segmentation for the parameters is as follows: Figure 3 As shown:

[0079] Table 2

[0080] Segment ai bi ci 1 92 77 15 2 -28 -53 25 3 95 98 -3 4 -58 -26 -31

[0081] The variation diagram of suspended weight loss along the path can be obtained using the aforementioned simulation method. Figure 2 Curve 3 in the figure). Then, the suspension weight loss curve is fitted with the theoretical suspension weight change curve to obtain the curve result containing the suspension weight loss ( Figure 2 As shown in curve 4), it is basically consistent with the actual suspension weight, which proves the effectiveness of this method.

[0082] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method of calculating a load simulation, characterized by, The method comprises the following steps: Step 1: Obtain parameters of the work well and the running casing by measurement, including the length r and equivalent weight m of a certain section of the casing being calculated eq the inclination θ and path friction coefficient μ of the section of casing at the position in the work well; Step 2: Obtain the axial component of the casing equivalent weight in the section of the well F from the parameters obtained in step 1 a (r) the frictional resistance generated by the casing during its travel in the section of the well F f (r) and the dead weight loss F generated by the casing in the section of the well, other than due to the frictional resistance L (r), the dead weight H is obtained from the following calculation model hk (r): H hk (r) = F a (r) - F f (r) - F L (r); In step 2, the calculation model is specifically as follows: Wherein g is the acceleration of gravity; When the engineering calculation is convenient, the suspended load H of the whole casing n The casing is divided into n segments, and θ and m between the segments are calculated eq The n segments are integrated and accumulated, and the following calculation model is used to solve: wherein S n is the total path length of the running in, F L (S n ) is the loss of the suspended load under S n path; F L (S n ) are determined as follows: Step 1: When the first operation of the well in a block is suspended simulation calculation, F L (r) is 0, the ideal state of the casing into the change curve of the suspended weight; Step 2: obtaining the actual hanging weight change curve during the casing running operation; Step 3: The loss of suspension weight change graph under the path can be simulated by the difference between the ideal suspension weight change curve and the actual suspension weight change curve, and then F L (S n ); The calculation method is suitable for the simulation of the hanging weight when one or more temporary barriers are added in the casing, the temporary barriers divide the casing into several parts, and the same or different medium is poured into the casing parts.

2. The method of claim 1, wherein: When the position of the casing meets the following conditions, the HW zero point is reached: cos θ = μ sin θ or Wherein θ ∈ [0, π / 2].

3. The method of claim 1, wherein: The temporary barrier is a float collar.

4. The method of claim 1, wherein: The medium includes mud, water and air with different specific gravities.

5. The method of claim 1, wherein: The calculation method is suitable for oil wells and gas wells.

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