Characteristics of sustained annular pressure and fluid distribution in high pressure and high temperature gas wells considering multiple leakage of tubing string

The temperature profile plays an important role in well integrity, flow assurance, and well test. Meanwhile, the impact of engineering conditions should not be ignored while calculating the well temperature profile. Therefore, in this study, we established a model to analyze the changing law of the temperature profile inside the production string of a high-pressure/high-temperature gas well (HPHT gas well). The proposed model considers the flow friction caused by a high production rate. Meanwhile, the variations in gas properties are taken into account to increase the model accuracy, including gas density, flow velocity, and viscosity. The analysis indicates that the temperature in the production string decreases more and more quickly from the reservoir to the wellhead. The wellhead temperature changes more and more slowly with time. When the reservoir temperature is too low to maintain production, it is useful to regulate the production rate or inject the thermal insulating fluid into the annulus to avoid the block caused by wax deposition or hydrate deposition. Considering the sensitivity, feasibility, and cost, it is recommended to change the well temperature profile by adjusting the production rate. If not applicable, the thermal conductivity can also be optimized to change the temperature profile.

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“…An HPHT gas well is selected from Ref. [40] as a case well to study the changing law. The basic parameters can be found in the reference.…”

Section: Changing Law Of the Temperature Profile Changing Law Under D...mentioning

confidence: 99%

Sensitivity analysis of the temperature profile changing law in the production string of a high-pressure high-temperature gas well considering the coupling relation among the gas flow friction, gas properties, temperature, and pressure

Cao

Sun

Zhang³

et al. 2022

Front. Phys.

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“…Annular pressure is an important issue in well quality due to its high risk and relatively wide distribution. Up to now, this phenomenon has been reported in deepwater wells [1][2][3], shale gas wells [4], geothermal wells [5], high-pressure and high-temperature gas wells [6,7], gas storage wells [8,9], steam injection wells [10] and gas injection wells [11]. Therefore, great effort has been devoted to related research, including mechanisms, predictions, management, and mitigation.…”

Section: Introductionmentioning

confidence: 99%

Analysis of Multiple Annular Pressure in Gas Storage Well and High-Pressure Gas Well

Cao¹,

Sun²,

Zhang³

et al. 2023

Energy Engineering

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In gas storage or high-pressure gas wells, annular pressure is an unavoidable threat to safe, long-term resource production. The more complex situation, however, is multiple annular pressure, which means annular pressure happens in not only one annulus but two or more. Such a situation brings serious challenges to the identification of well integrity. However, few researches analyze the phenomenon of multiple annular pressure. Therefore, this paper studies the mechanism of multi-annular pressure to provide a foundation for its prevention and diagnosis. Firstly, the multi-annular pressure is classified according to the mechanism and field data. Then the failure mechanism and function of the wellbore safety barriers in the process of passage formation are analyzed. Finally, some suggestions are put forward for identifying and controlling multi-annular pressure. The results show that gas storage wells and high-pressure gas wells have the conditions to generate pressure channels, which leads to the expansion of annular pressure from a single annulus to multiple annuli. The pressure channel is composed of the tubing string, casing string, and a cement mantle, and the failures among the three have causal and hierarchical relationships. According to the channel direction, it can be divided into two types: tubing-casing annulus to casing annulus and casing annulus to the tubing-casing annulus, of which the former is more harmful. Some measures can be considered to prevent pressure channeling, including improvement of cementing quality, revision of maximum allowable annular pressure, and suitable frequency of pressure relief. KEYWORDSMultiple-annular pressure; pressure channel; generation mechanism; identification and control Nomenclature ACross section area of cement mantle, cm 2 H l Height of gas column, m; V gan is the volume of gas column, m 3 K e Comprehensive permeability of cement, μm 2 L Length of cement mantle, cm; p e is gas reservoir pressure, MPa K T Isothermal compressibility of annular liquid, MPa −1 Rs Gas solubility of annular liquid, m 3 /m 3 T a Gas temperature under standard conditions, K

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“…2 Analysis of rules related to abnormal A-annular pressure 2.1 A-annular pressure mechanism A-annular pressure has three origins (Bradford et al, 2004;Tao et al, 2011;Zeng et al, 2019;Zhang et al, 2021): 1.) Annular pressure caused by thermal effect in the wellbore.…”

Section: Introductionmentioning

confidence: 99%

Research on safety early warning of abnormal A-annular pressure of “three-high” gas wells based on data mining

Yan

Qi²,

Wu³

et al. 2023

Front. Earth Sci.

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A major safety accident will be triggered when the A-annular pressure value of high pressure, high productivity and high sulfur gas well exceeded the maximum allowable value. The A-annular pressure value of high pressure high productivity and high sulfur gas well once exceeded the allowable value will trigger a major safety accident. Therefore, this paper proposed a data mining based the gas well early warning strategy by analyzing the annular pressure mechanism and the change in the pattern of instantaneous gas volume, well temperature, and annular pressure in various conditions. To summarize, the law of gas well abnormal A-annular pressure is aimed at constructing a gas well safety warning rule for gas well stable production stage and shutdown period where the initial parameters setting in the early warning rule and adjustment optimization mechanism is also determined. Lastly, with the use of historical abnormal samples, the gas well early warning strategy bought up in this paper was verified. The example shown that compared with the traditional DCS system warning strategy, the gas well safety early warning strategy can identify the abnormal A-annular pressure phenomenon 82 h in advance thus achieving production safety management.

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Characteristics of sustained annular pressure and fluid distribution in high pressure and high temperature gas wells considering multiple leakage of tubing string

Cited by 25 publications

References 33 publications

Sensitivity analysis of the temperature profile changing law in the production string of a high-pressure high-temperature gas well considering the coupling relation among the gas flow friction, gas properties, temperature, and pressure

Sensitivity analysis of the temperature profile changing law in the production string of a high-pressure high-temperature gas well considering the coupling relation among the gas flow friction, gas properties, temperature, and pressure

Analysis of Multiple Annular Pressure in Gas Storage Well and High-Pressure Gas Well

Research on safety early warning of abnormal A-annular pressure of “three-high” gas wells based on data mining

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