Wellbore Stability of a Deep-Water Shallow Hydrate Reservoir Based on Strain Softening Characteristics

Feng, Wenrong; Li, Danqiong; Wang, Guorong; Song, Yujia

doi:10.1155/2020/8891436

Cited by 5 publications

(3 citation statements)

References 25 publications

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“…As a result, the decomposition of hydrate occurred, weakening the strength of the hydrate formation. This could lead to wellhead subsidence and potential damage to equipment on the seabed [14,15], although…”

Section: Introductionmentioning

confidence: 99%

Numerical Simulating the Influences of Hydrate Decomposition on Wellhead Stability

et al. 2023

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Natural gas hydrate reservoir has been identified as a new alternative energy resource which has characteristics of weak cementation, low reservoir strength and shallow overburden depth. Thus, the stability of subsea equipment and formation can be affected during the drilling process. To quantitatively assess the vertical displacement of the formation induced by hydrate decomposition and clearly identify the influence laws of various factors on wellhead stability, this study established a fully coupled thermo-hydro-mechanical-chemical (THMC) model by using ABAQUS software. The important factor that affects the wellhead stability is the decomposition range of hydrates. Based on this, the orthogonal experimental design method was utilized to analyze the influence laws of some factors on wellhead stability, including the thickness of hydrate formation, initial hydrate saturation, overburden depth of hydrate sediment, and mudline temperature. The results revealed that the decomposition of hydrate weakens the mechanical properties of the hydrate formation, thus leading to the compression of the hydrate formation, further causing the wellhead subsidence. When the duration of drilling operations was 24 h and no decomposition of natural gas hydrate occurs, the wellhead subsidence is recorded at 0.053 m, this value increases with an increase in drilling fluid temperature. The factors were listed in descending order as following, according to their significance of influences on wellhead stability: the thickness of hydrate formation, initial hydrate saturation, overburden depth of hydrate sediment, and mudline temperature. Among the above factors, statistical significance of the mudline temperature was less than 15% confidence level, suggesting that the effect of mudline temperature on wellhead stability is negligible. These findings not only confirm the influence of hydrate decomposition on wellhead stability, but also suggest important implications for the drilling of hydrate-bearing formation.

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Section: Introductionmentioning

confidence: 99%

Numerical Simulating the Influences of Hydrate Decomposition on Wellhead Stability

et al. 2023

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“…Interactions between drilling fluid in drilling annulus space and hydrate formation will cause the temperature and pressure conditions changed during drilling [11][12][13]. As a result, caused the decomposition of hydrate and weakens the strength of hydrate formation which may damage equipment on the seabed [14,15]. That's why the drilling of hydrate-bearing strata remains such a great engineering challenge [16,17].…”

Section: Introductionmentioning

confidence: 99%

Numerical simulating the influences of hydrate decomposition on wellhead stability

Cheng

Xue

Shi

et al. 2023

Preprint

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Natural gas hydrate has been identified as a new alternative energy resource which has characteristics of weak cementation, low reservoir strength and shallow overburden depth. Thus, the stability of subsea equipment and formation can be affected during the drilling process. To quantitative assessment on the vertical displacement of the strata induced by hydrate decomposition and clearly learn the influence laws of various factors on wellhead stability, this study established a fully coupled thermo-hydro-mechanical-chemical (THMC) model by ABAQUS. The important factor that affects the wellhead stability is the decomposition range of hydrate. Based on this, the orthogonal experimental design method was utilized to analyze the influence laws of some factors on wellhead stability, including the thickness of hydrate formation, initial hydrate saturation, overburden depth of hydrate sediment, and mudline temperature. The results revealed that, the decomposition of hydrate weakens the mechanical properties of the hydrate formation, thus leading to the compression of the hydrate formation, further causing the wellhead subsidence. The factors were listed in descending order as follows according to their significance of influences on wellhead stability: the thickness of hydrate formation, initial hydrate saturation, overburden depth of hydrate sediment, and mudline temperature. In particular, the effect of mudline temperature on wellhead stability is negligible. Hence, these findings not only confirm the influence of hydrate decomposition on wellhead stability, but also provide important implications for the drilling of hydrate-bearing strata.

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“…One of the most widely used empirical criteria in the anisotropic rock is the single-weak plane failure criterion. Since its first introduction by Jaeger [2] in extending the earlier work of Bott [1], the single-weak plane failure criterion has been used successfully in evaluating wellbore stability [5][6][7][8][9][10][11][12][13]. In this criterion, the failure of both the bedding planes and rock matrix is described by using the Mohr-Coulomb criterion by two dif-ferent sets of intact rock and weak plan constants.…”

Section: Introductionmentioning

confidence: 99%

Analytical and Experimental Investigations on Mechanical Properties of Weak Plane Bedding in Mudstone

et al. 2021

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Wellbore instabilities frequently occur in mudstone formation with weak plane bedding because of strong anisotropies. The mechanics parameters of weak plane bedding are of vital significance to the wellbore stability analysis for mudstone formations. The conventional method for determining the mechanics parameters is to fit lots of triaxial test data due to the blindness of coring. In this paper, an evaluation method of the mechanics parameters of weak plane bedding is proposed to improve the accuracy of weak plane bedding mechanical properties. The mechanics parameters of weak plane bedding are obtained by combing the single-weak plane failure criterion with the compressive strength of rock obtained by the triaxial test of cores with different coring angles. It is seen that the new evaluation method is simple and convenient. On the other hand, a validation method of the mechanics parameters of weak plane bedding is proposed to ensure their accuracy. The compressive strength obtained from the core with the special coring angle is compared with the theoretical compressive strength for verifying the accuracy of weak plane bedding mechanical properties. It is observed that the proposed evaluation and validation methods can be used to measure the value of weak plane bedding mechanical properties precisely. The proposed methods are general and can be used for measuring the mechanical properties of fracture weak-plane and joint weak-plane.

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Wellbore Stability of a Deep-Water Shallow Hydrate Reservoir Based on Strain Softening Characteristics

Cited by 5 publications

References 25 publications

Numerical Simulating the Influences of Hydrate Decomposition on Wellhead Stability

Numerical Simulating the Influences of Hydrate Decomposition on Wellhead Stability

Numerical simulating the influences of hydrate decomposition on wellhead stability

Analytical and Experimental Investigations on Mechanical Properties of Weak Plane Bedding in Mudstone

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