3D Stress Field Modeling for Wellbore Stability Analysis

Abstract

Borehole collapse is one of the difficult problems in offshore oilfield drilling, which is directly related to regional geostress field. Seismic inversion is widely used to construct 3D stress field, and the accuracy of seismic inversion results depends heavily on the quality of seismic data. Therefore, in the development oilfield with poor seismic data quality, we use attribute modeling method to construct high-precision 3D geostress field to help analyze the wellbore stability of oilfield development wells. First, 3D structural model is created by using seismic interpretation horizon and fault. Then, the 3D stress body is constructed by filling the vertical and horizontal attributes according to certain constraints by using the known geostress values at the wellbore of the drilled development wells. P oilfield is a large Neogene oilfield located in Bohai Bay. The serious expansion of the wellbore in the shallow unconsolidated sandstone in the oilfield area leads to high engineering risks. Moreover, due to the influence of large-scale gas cloud area, the effective wave energy on seismic profile is submerged. Through the above attribute modeling method, the high-precision 3D geostress field of P oilfield is successfully constructed. Practical application shows this method is suitable for the evaluation of geostress and wellbore stability analysis in areas with high well control in the middle and late stages of oilfield development. Especially in the area where the seismic data is not reliable enough, the 3D modeling results of this method has higher accuracy than the seismic inversion results.