Deformation mechanism and numerical simulation of interface dislocation in composite salt gypsum layer
LI Shiyuan1, 2, LI Fuyao1, YANG Liu3, LU Yunhu1
1 School of Petroleum Engineering, China University of Petroleum-Beijing, Beijing 102249, China 2 State Key Laboratory of Petroleum Resources and Prospecting, China University of Petroleum-Beijing, Beijing 102249, China 3 State Key Laboratory of Geomechanics and Deep Underground Engineering, China University of Mining and Technology , Beijing 100083, China
The salt rock in the sedimentary basin is the highest quality cap rock, and 80%~90% of the world’s oil and gas resources are buried under it. It is not only the focus of the world petroleum industry, but also the focus of China’s oil and gas resources development. China’s deep salt oil and gas resources are abundant. At present, 40% of China’s newly discovered oil and gas resources are located under the deep salt layer. In the oil and gas drilling process, the extent and frequency of damage to the casing under the salt is serious. According to statistics, nearly 50% of the casing damage occurs at the interface position of the composite salt gypsum layer. In this paper, the creep test of salt rock specimens is first surveyed, and the general law of salt rock creep under uniaxial conditions is mainly explored. Then, the stability of the composite salt gypsum layer was studied. Through the investigation of the analysis of the damage characteristics of the existing salt gypsum layer, it was found that the dislocation factor was still relatively lack of consideration. The paper concentrates on the main control factors of interface misalignment
and the mechanism of deformation of the casing, establishes the criterion for the slippage of the fault layer, establishes the stratum-casing numerical simulation through ABAQUS, comprehensively considers the degree of interface cementation, and the elastic modulus of the salt gypsum layer. The influence of the amount, Poisson’s ratio, formation inclination and creep characteristics on casing damage. Finally, based on this, the prevention and control measures of casing deformation are proposed,including the optimal design of casing structure under the condition of composite salt gypsum layer.
composite salt gypsum layer; interface dislocation; casing deformation