Study on Influx Risk Evaluation of Horizontal Gas Wells With High-Pressure High-Temperature in the South China Sea

2020 ◽  
Author(s):  
Ming Luo ◽  
Deli Gao ◽  
Xin Zhao ◽  
Yuan Chen ◽  
Yupeng Yang ◽  
...  
Keyword(s):  
High Pressure ◽  
High Temperature ◽  
South China Sea ◽  
Risk Evaluation ◽  
Control Strategies ◽  
Control Design ◽  
Gas Wells ◽  
Well Control ◽  
High Pressure High Temperature ◽  
Open Hole

Abstract The South China Sea has rich natural gas source with typical high-pressure high-temperature (HPHT) and the extremely narrow drilling window, which leads to frequent influx, even borehole abandonment. However, horizontal gas wells have been placed in the area to develop the gas reservoir, which presents greater well control challenges. Therefore, the influx risk evaluation is quite necessary to guide the well control design. Firstly, the influx mechanism is analyzed based on gas intrusion to provide a theoretical basis for well control design. It is found that influx usually occurs when drilling the high-temperature stratums and target layers. Secondly, the relationship between horizontal open-hole length and influx volume is calculated under different reservoir permeability, reservoir thickness, negative bottom hole pressure and horizontal open-hole section length. Thirdly, the characteristics of gas-liquid two-phase flow are described. Fourthly, the inflow risk evaluation and well control strategies of the target horizontal gas wells are proposed, and the influx risk evaluation envelope was established. The influx risk evaluation and well control strategies have been successfully applied to the DF gas field featuring offshore HPHT. Horizontal gas wells were drilled in the micro pressure window without accidents and the well cost was significantly reduced.

Utilizing Novel Expandable Steel Packers to Overcome Multi-Stage Fracturing Completion Deployment Challenges in Horizontal Gas Wells

2021 ◽  
Author(s):  
Ebikebena M. Ombe ◽  
Ernesto G. Gomez ◽  
Aldia Syamsudhuha ◽  
Abdullah M. AlKwiter
Keyword(s):  
High Pressure ◽  
High Temperature ◽  
Cost Effective ◽  
Outer Diameter ◽  
Gas Wells ◽  
Multi Stage ◽  
High Pressure High Temperature ◽  
Zonal Isolation ◽  
Gas Bearing ◽  
Productive Time

Abstract This paper discusses the successful deployment of Multi-stage Fracturing (MSF) completions, composed of novel expandable steel packers, in high pressure, high temperature (HP/HT) horizontal gas wells. The 5-7/8" horizontal sections of these wells were drilled in high pressure, high temperature gas bearing formations. There were also washed-outs & high "dog-legs" along their wellbores, due to constant geo-steering required to keep the laterals within the hydrocarbon bearing zones. These factors introduced challenges to deploying the conventional MSF completion in these laterals. Due to the delicate nature of their packer elastomers and their susceptibility to degradation at high temperature, these conventional MSF completions could not be run in such hostile down-hole conditions without the risk of damage or getting stuck off-bottom. This paper describes the deployment of a novel expandable steel packer MSF completion in these tough down-hole conditions. These expandable steel packers could overcome the challenges mentioned above due to the following unique features: High temperature durability. Enhanced ruggedness which gave them the ability to be rotated & reciprocated during without risk of damage. Reduced packer outer diameter (OD) of 5.500" as compared to the 5.625" OD of conventional elastomer MSF packers. Enhanced flexibility which enabled them to be deployed in wellbores with high dog-leg severity (DLS). With the ability to rotate & reciprocate them while running-in-hole (RIH), coupled with their higher annular clearance & tolerance of high temperature, the expandable steel packers were key to overcoming the risk of damaging or getting stuck with the MSF completion while RIH. Also, due to the higher setting pressure of the expandable steel packers when compared to conventional elastomer packers, there was a reduced risk of prematurely setting the packers if high circulating pressure were encountered during deployment. Another notable advantage of these expandable packers is that they provided an optimization opportunity to reduce the number of packers required in the MSF completion. In a conventional MSF completion, two elastomer packers are usually required to ensure optimum zonal isolation between each MSF stage. However, due to their superior sealing capability, only one expandable steel packer is required to ensure good inter-stage isolation. This greatly reduces the number of packers required in the MSF completion, thereby reducing its stiffness & ultimately reducing the probability of getting stuck while RIH. The results of using these expandable steel packers is the successful deployment of the MSF completions in these harsh down-hole conditions, elimination of non-productive time associated with stuck or damaged MSF completion as well as the safe & cost-effective completion in these critical horizontal gas wells.

Friction-wear failure mechanism of tubing strings used in high-pressure, high-temperature and high-yield gas wells

Wear ◽  
2021 ◽  
Vol 468-469 ◽  
pp. 203576
Author(s):  
Xiaoqiang Guo ◽  
Jun Liu ◽  
Liming Dai ◽  
Qingyou Liu ◽  
Dake Fang ◽  
...  
Keyword(s):  
High Pressure ◽  
High Temperature ◽  
Failure Mechanism ◽  
High Yield ◽  
Gas Wells ◽  
High Pressure High Temperature

Wear Experiment and Influencing Factors Analysis of 13Cr-L80 Tubing String in High-Pressure, High-Temperature and High-Yield Gas Wells

2021 ◽  
Vol 1026 ◽  
pp. 169-175
Author(s):  
Xiao Qiang Guo ◽  
Jun Liu ◽  
Liang Huang ◽  
An Chao Wei ◽  
Da Ke Fang
Keyword(s):  
High Pressure ◽  
High Temperature ◽  
Service Life ◽  
Longitudinal Vibration ◽  
Control Variable ◽  
Contact Load ◽  
High Yield ◽  
Gas Wells ◽  
High Pressure High Temperature ◽  
Tubing String

Due to wear failures caused by tubing string vibrations in high-pressure, high-temperature and high-yield (3H) gas wells, a wear experiment was performed on the 13Cr-L80 tubing string. The influence of contact load, friction frequency, and reciprocating stroke length on the wear characteristics of the tubing string were effectively analyzed using the control variable method. The results demonstrate that, the wear patterns of the tubing-casing were primarily abrasive and adhesive wears, with minimal corrosion wear. The wear amount of tubing increases linearly with the increase of contact load and reciprocating stroke, but increases nonlinearly with the increase of friction frequency, and the friction coefficient of tubing string do not change with the increase of contact load, friction frequency and reciprocating stroke. In-field operations, the service life of the tubing string in 3H gas wells can be effectively augmented by reducing the contact load and longitudinal vibration displacement of the tubing-casing, maintaining the vibration frequency of the tubing string below 1.5 Hz. These results provide useful guidance for designing and implementing approaches to improve the service life of tubing strings in high-yield gas wells.

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