Study On Anti - Crowding Strength Design Of Layers Of Horizontal Wells In

Yingmaili area subsalt has enormous geologic reserves of oil and gas. In order to improve producing degree, Tarim Oilfield uses horizontal well technology to develop subsalt. Curve section of horizontal well is located in salt-gypsum layer, the casing is easy to collapse because of salt-gypsum layer creeping and bending stress.In order to put forward the suitable casing collapsing strength design method and reduce the risk of casing collapse. Based on the research and analysis of Yingmaili area horizontal well beneath casing deformation, this thesis first established the optimization geostress calculation model namely Huang model, determined the salt-gypsum layer creep constitutive relation, established the salt-gypsum layer curve section casing outside extrusion force finite element model. Secondly, established salt-gypsum layer curve section casing collapsing strength calculation formula on the basis of previous studies. Finally, put forward the suitable casing collapsing strength design method of Yingmaili area horizontal well and made the Visual Basic program. The main research results are as follows.(1)The main cause of casing deformation in Yingmaili area horizontal well beneath the salt-gypsum layer curve section is the casing collapsing strength is not enough to bear the salt-gypsum layer creep outside squeezing force.(2)This thesis took the optimized Huang model as salt-gypsum layer curve section geostress calculation model. Then transformed the ground stress into vertical wells stress and applied on the finite element model as the load according to the transform formula.Determine the creep parameters of Yingmaili salt-gypsum layer. The casing’s outside extrusion force finite element model was established by the determined parameters, then this thesis analyzed the hole deviation angle and well azimuth and formation creep’s influence to the casing maximum extrusion force and extrusion force uneven coefficient.(3)By making appropriate modifications to the Hanjianzeng formula on basis of Huanggenlu’s casing bending stress influence coefficient, this thesis established salt bed curve section casing calculation formula and also analyzed the non-uniform outside force, borehole curvature, manufacturing defects’s affect on casing collapsing strength, it lead us to the conclusion that non-uniform extrusion force outside of deflection had the greatest effect in the period of casing collapsing strength, borehole curvature influenced the second, manufacturing defect influenced the least. A Visual Basic program was made according to the formula of the casing collapsing strength simultaneously.(4)This thesis put forward the Yingmaili salt-gypsum layer curve section’s casing collapsing strength design method based on the casing’s outside extrusion force finite element model and casing calculation formula in this thesis, designed as a case study of YM7-H1well and also made a Visual Basic program, it provided reference for the choice of this area’s casing.