ABSTRACT: The creep of multiple thick salt-gypsum formations was severe in the Xinghuo area of the Tarim Basin, and it was difficult to control directional trajectory and drilling fluid density. In this paper, the three-dimensional creep model of composite salt paste layers was established by the finite element method to explore the creep characteristics of salt-gypsum formations in the Xinghuo area. The influence law of well inclination Angle and the Azimuth Angle on the creep of salt-paste layer was analyzed. The study showed that with the increase of deviation angle, the hole shrinkage value first decreased and then increased. With the rise of azimuth angle, the hole shrinkage value increased in both short and long axis directions. When designing the directional well trajectory in the salt gypsum interval, the deviation angle of the salt gypsum interval should be 35˚ ~ 55˚. At the same time, it should be avoided to twist the azimuth when the deviation angle was slight. A reasonable drilling fluid density window was established according to the borehole stability model, which was expected to guide the field formulation of the technical scheme for the safe drilling of giant thick salt-gypsum rock directional borehole in the Xinghuo area.

Keywords:
directional drilling, drilling fluid density, reservoir characterization, drilling operation, salt-gypsum formation, wellbore integrity, upstream oil & gas, reservoir geomechanics, wellbore design, mudstone
Subjects:
Wellbore Design, Drilling Operations, Reservoir Characterization, Information Management and Systems, Wellbore integrity, Directional drilling, Reservoir geomechanics
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