The Analysis of Compression Forces on Casing and Cement duringProduction

摘要

The effect of borehole compression forces on casing and cement is a major concern to engineerscompleting well. According to API standards of Casing Design, casing is compressed by hydrostaticpressure and continuous changing reservoir pressure that occurs around the oil well and water wellduring production. Evaluation of effects of changing loads on casing and cement is involved in thispaper.First, the compression forces on casing and cement during production under condition just followingcompletion are discussed. It is investigated that the loads on casing and cement may increasegradually with sediment accumulation and pore pressure drop after long production in Stratigraphicoil-gas reservoirs. Second, by applying the theoretical model of immiscible saturated two-phase (oil& water) flow in nonlinear porous media, the finite element codes for computation are programmed.Finally, with the assumption that the casing and cement consolidate well with porous media inreservoir, a 3D model is established, in which the parameters of the oil well are adopted fromGudong Production Plant, Shengli Oilfield, China. It is shown that stresses in casing and cementwill increase after high-intensity development, which might result in the casing deformation.