OPTIMIZATION OF PIPE CONNECTION IN THE OIL AND GAS INDUSTRY

Prepared by: Ademi Islyam

      Lunara Kublasheva

      Daulet Zhumat 

​

Supervisor: Batyr K. Naurushev

Almaty, 2024

2

AGENDA

1.   Purpose and objectives of the study
2. Problem statement
3. Literature review:

3.1 tubing type selection

4. Proposed solution

1. Hyposisys
2. Design of the tubing
3. Methodology

7.1 fusion 3d modeling of the tubing

7.2 ansys flow simulation

8. Results:

8.1 Simulation results

8.2 Manual calculations results

8.3 Validation of manual results

9. Economical calculations

10. Comparison of the proposed tubing and basic design

1. Conclusion

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 Purpose of the study: to find the type of pipe connection for 

which optimization is most necessary in modern reality.

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 Objectives:

• Conduct review and analysis of data sources on the study topic
• Analyze pipe connections
• Identify the problem
• Determine a solution
• Build 3D model of threaded pipe connection 
• Complete tests on the pipe
• Pressure and stress reaction tests
• Gas flow and leakage tests
• Make calculations and compare with automatic results
• Calculate economical profit
• Make a conclusion

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​

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 After analyzing pipe connections, tubing was found to be the most in need of optimization due to reasons mentioned below in the Table 1.

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Table 1 – Pipe connection optimization reasoning

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TUBING TYPES

Table 2 – comparison evaluation

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 Gas leakage is one of the significant problems for tubing connections as show the accidents over the recent years.

 Accidents on field:

• TOO “Buzachi Neft”: Methane release at the Karaturun field. Natural gas fire at well No. 303 (2023)
• NCOC: Gas leakage at Kashagan field (2013 and 2022)

 As international crude oil prices continued to go down over the past two years and the exploitation difficulty of remaining oil and gas blocks continues to increase, oil companies urgently need to reduce the cost of casing. Seal ledge is usually adopted for sealing, so the cost cannot be significantly reduced.

API round thread is currently the thread type with the lowest relative cost. Therefore, great economic benefit will be made if a kind of low-cost gas-tight thread can be developed to replace the existing premium thread. It will also be a revolutionary innovation.

CONSIDERED PROBLEM

Table 3 - Causes and consequences of gas leakage​

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Because of the structural design, after the API tubing thread is engaged, there is a spiral leakage channel between the tooth crest and the tooth bottom, which connects the inner space and the outer space of the casing. Due to the existence of the leakage channel, the API round thread theoretically does not have fluid sealing capability, so it is generally not used as gas-tight thread.

Great economic benefit will be made if a kind of low-cost gas-tight thread can be developed on the basis of API round thread with a relatively lowest cost to replace the existing premium thread

Table 4 –Tubing properties

THE PROPOSED SOLUTION

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Fig.1 - Initial drawing of a pipe connection

By incorporating an elastic sealing ring within the collar, the seal is achieved through the precise fit between the sealing ring and the casing thread.

Fig.2 - Seal connection and detailed view

DESIGN OF THE TUBING WITH API THREAD AND ELASTIC RING

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USED SOFTWARE PROGRAM

Autodesk Fusion software developed by Autodesk and includes computer-aided design (CAD), computer-aided manufacturing (CAM), computer-aided engineering (CAE) and printed circuit board (PCB) design systems.  

Was used for designing and modeling the pipe and collar.

Tests conducted in Fusion:

• Internal pressure test
• Hydrostatic pressure test

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ANSYS

Finite element analysis software 

developed by "Ansys inc" which provides an information of how given product will work or not work in real conditions.

Was used to make simulation of gas flow in the tubing.

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Fig. 3 – Internal pressure test 

TESTS AND ANALYSES

 Using the Fusion 360 program, a test was performed to determine the safety factor of tubing by the action of internal flow pressure. This allowed us to determine whether the pipe will withstand the load. Our pipe can withstand a load of 50 MPa, which corresponds to the required result

Fig. 4 – Hydrostatic pressure test 

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TESTS AND ANALYSES​

Fig. 6 – Gas flow simulation in the tubing without a sealing ring​

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Fig. 5 – Gas flow simulation in the tubing with a sealing ring

 To simulate gas flow and check for the risk of gas release Ansys software was used. In the test, the gas sealing performance of the tubing thread connector under the conditions of tension, compression and temperature was mainly evaluated, the load condition of the downhole tubing was simulated.

TESTS AND ANALYSES​

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TESTS AND ANALYSES​

Fig. 7 – Location of tubing in Ansys coordinates  

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TESTS AND ANALYSES​

Fig. 8 - Velocity of flow in tubing without sealing ring

 The x-axis shows the coordinates that were mentioned earlier. To build a graph, you need to draw a line inside the pipe indicating the coordinates. Interval of x-line values is very low, hence the pipe graph with a curved ring. If the interval of the x-axis were significant, then the graph would be smooth. Therefore, in the fig.10 the line deviates very strongly, which means a leakage.

Fig. 9 - Velocity of flow in tubing with sealing ring​

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TESTS AND ANALYSES​

Fig. 10 - Gas loss in tubing without sealing ring

Fig. 11 - Velocity of flow in tubing with sealing ring

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TESTS AND ANALYSES​

Fig. 12 - Mass flow calculation in Ansys

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CALCULATIONS

(Eq.1)

(Eq.2)

(Eq.3)

(Eq.4)

(Eq.5)

(Eq.6)

(Eq.8)

For hydrostatic pressure test:

For internal pressure test:

(Eq.7)

(Eq.9)

(Eq.11)

(Eq.10)

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CALCULATIONS

Table 6 – Well Data

(Eq.12)

(Eq.13)

(Eq.15)

(Eq.16)

(Eq.17)

Table 5 – Calculation results

(Eq.14)

(Eq.18)

(Eq.19)

(Eq.20)

(Eq.21)

(Eq.22)

(Eq.24)

(Eq.23)

(Eq.25)

(Eq.26)

(Eq.27)

(Eq.28)

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ECONOMICAL PART

Table 7 – Total money loss

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ECONOMICAL PART

Table 8 – Total for tubing with sealing ring

 During the entire time of gas production, there was a gas leak with a flow rate of 21.3 cubic meters per hour. More than 5 million tenge was lost, to be more precise 5 134 738 tenge. 

Using a polymer sealing ring, it would be possible to avoid gas leakage and save more than 5 million tenge.

​

 In the table below you can see the price for tubing, a sealing ring and for the work of an employee at the field. This tubing with a sealing ring will be cheaper than other tubing connections. For example, the most common tubing with an integral joint costs 463,422 tenge more.

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CONCLUSION

 The cost of the gas-tight thread developed on the basis of the API round thread is about 1.3 times that of the API round thread. Therefore, at least 27% of the casing cost can be saved and considerable economic benefits can be made if this gas-tight thread is used to replace the current widely-used premium thread.

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 The analysis shows that the thread structure has a good sealing performance and stability. In recent years, there has been an increasing interest in CO₂ storage and flooding projects at home and abroad, where cost is a key issue restricting such projects. The proposed thread structure can effectively prevent the leakage of the wellbore in the CO₂ storage and flooding projects and can reduce the casing cost. If high-grade steel pipes are used, the sealing capacity of such thread sealing structure will be further improved to meet higher-pressure working conditions.

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 Great economic benefit will be made if a kind of low-cost gas-tight thread can be developed on the basis of API round thread with a relatively lowest cost to replace the existing premium thread.

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1. J. Van Wittenberghe , P. De Baets , W. De Waele , T. Galle , T.T. Bui and G. De Roeck. Design characteristics that improve the fatigue life of threaded pipe connections, 2011.
2. T. Galle, W. De Waele, P. De Baets, J. Van Wittenberghe. Influence of design features on the structural integrity of threaded pipe connections, 2011.
3. Guo Jianchun, Gou Bo, Wang Kunjie, Ren Jichuan, Zeng Ji. An optimal design of network-fracture acidification for ultra-deep gas wells in the Lower Permian strata of the western Sichuan basin, 2017.
4. Xie Zengye, Wei Guoqi, Zhang Jian, Yang Wei, Zhang Lu, Wang Zhihong, Zhao Jie. Characteristics of source rocks of the Datangpo Fm, Nanhua System, at the southeastern margin of Sichuan Basin and their significance to oil and gas exploration, 2017.
5. Zhang Yongqiang, Liu Li, Lu Jinfu, Yin Zhifu, Wang Ke, Liu Jie, Ta Chuan. Development of gas-tight threads based on API round threads and its evaluation, 2017.
6. Fan Shuanshi, Wang Xi, Lang Xuemei, Wang Yanhong. Energy efficiency simulation of the process of gas hydrate exploitation from flue gas in an electric power plant, 2017.
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9. Khlebnikov V.N., Antonov S.V., Mishin A.S., Liang Meng, Khamidullina I.V., Zobov P.M., Likhacheva N.V., Gushchin P.A. Major factors influencing the generation of natural gas hydrate in porous media, 2017.
10. Zhang Yongping, Yang Yanhui, Shao Guoliang, Chen Longwei, Wei Ning, Zhang Liwen. Problems in the development of high-rank CBM horizontal wells in the FanzhuangeZhengzhuang Block in the Qinshui Basin and countermeasures, 2017.
11. You Lijun, Kang Yili, Chen Qiang, Fang Chaohe, Yang Pengfei. Prospect of shale gas recovery enhancement by oxidation-induced rock burst, 2017.
12. Yin Yiyong, Su Yinao, Wang Zhaohui. Vibration characteristics of casing string under the exciting force of an electric vibrator, 2017.

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