Simulating the Effect of Hydrate Dissociation on Wellhead Stability During Oil and Gas Development in Deepwater  

作　　者：LI Qingchao CHENG Yuanfang ZHANG Huaiwen YAN Chuanliang LIU Yuwen 

机构地区：[1]School of Petroleum Engineering, ChinaUniversity of Petroleum (East China)

出　　处：《Journal of Ocean University of China》2018年第1期35-45,共11页中国海洋大学学报（英文版）

基　　金：supported by the Program for the Changjiang Scholars and Innovative Research Team in University (No. IRT_14R58);the National Natural Science Foundation of China (No. 51704311);the Fundamental Research Funds for the Central Universities (No. 16CX06 033A);the National Key Research and Development Program (No. 2016YFC0304005);the National Basic Research Program of China (973 Program) (No. 2015CB251 201);the Qingdao Science and Technology Project (No. 15-9-1-55-jch)

摘　　要：It is well known that methane hydrate has been identified as an alternative resource due to its massive reserves and clean property. However, hydrate dissociation during oil and gas development(OGD) process in deep water can affect the stability of subsea equipment and formation. Currently, there is a serious lack of studies over quantitative assessment on the effects of hydrate dissociation on wellhead stability. In order to solve this problem, ABAQUS finite element software was used to develop a model and to evaluate the behavior of wellhead caused by hydrate dissociation. The factors that affect the wellhead stability include dissociation range, depth of hydrate formation and mechanical properties of dissociated hydrate region. Based on these, series of simulations were carried out to determine the wellhead displacement. The results revealed that, continuous dissociation of hydrate in homogeneous and isotropic formations can causes the non-linear increment in vertical displacement of wellhead. The displacement of wellhead showed good agreement with the settlement of overlying formations under the same conditions. In addition, the shallower and thicker hydrate formation can aggravate the influence of hydrate dissociation on the wellhead stability. Further, it was observed that with the declining elastic modulus and Poisson's ratio, the wellhead displacement increases. Hence, these findings not only confirm the effect of hydrate dissociation on the wellhead stability, but also lend support to the actions, such as cooling the drilling fluid, which can reduce the hydrate dissociation range and further make deepwater operations safer and more efficient.It is well known that methane hydrate has been identified as an alternative resource due to its massive reserves and clean property. However, hydrate dissociation during oil and gas development(OGD) process in deep water can affect the stability of subsea equipment and formation. Currently, there is a serious lack of studies over quantitative assessment on the effects of hydrate dissociation on wellhead stability. In order to solve this problem, ABAQUS finite element software was used to develop a model and to evaluate the behavior of wellhead caused by hydrate dissociation. The factors that affect the wellhead stability include dissociation range, depth of hydrate formation and mechanical properties of dissociated hydrate region. Based on these, series of simulations were carried out to determine the wellhead displacement. The results revealed that, continuous dissociation of hydrate in homogeneous and isotropic formations can causes the non-linear increment in vertical displacement of wellhead. The displacement of wellhead showed good agreement with the settlement of overlying formations under the same conditions. In addition, the shallower and thicker hydrate formation can aggravate the influence of hydrate dissociation on the wellhead stability. Further, it was observed that with the declining elastic modulus and Poisson's ratio, the wellhead displacement increases. Hence, these findings not only confirm the effect of hydrate dissociation on the wellhead stability, but also lend support to the actions, such as cooling the drilling fluid, which can reduce the hydrate dissociation range and further make deepwater operations safer and more efficient.

关 键 词：DISSOCIATION of HYDRATE oil and gas development in DEEPWATER WELLHEAD STABILITY finite element simulation 

分 类 号：P7[天文地球—海洋科学]