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为了研究超压对碎屑岩储层机械压实作用的抑制作用和预测超压背景下碎屑岩储层的孔隙度,本文根据压力平衡原理,推导了地层超压与有效埋深的关系方程,并在综合考虑超压、溶蚀和胶结作用的基础上,建立了超压背景下储层孔隙度的预测模型。结果表明,盆地中地层的密度越小,超压对碎屑岩储层机械压实的抑制效果越明显。三个不同时代、不同类型沉积盆地的孔隙度预测结果表明,应用本文建立的储层孔隙度预测模型所预测储层孔隙度的误差均低于Gluyas和Cade方程,而且孔隙度预测的误差随地层时代的变老而增大。在储层胶结物小于10%的条件下,新生代超压盆地碎屑岩储层孔隙度的预测误差小于2%,而中生代超压盆地储层孔隙度的预测误差大于5%。本文建立的超压背景下的碎屑岩储层孔隙度预测模型仅适用于时代较新超压盆地的孔隙度预测。
In order to study the inhibitory effect of overpressure on the mechanical compaction of clastic reservoirs and predict the porosity of clastic reservoirs under overpressure, according to the principle of pressure balance, the relationship between formation overpressure and effective buried depth is derived Based on the comprehensive consideration of overpressure, erosion and cementation, a prediction model of reservoir porosity under overpressure was established. The results show that the smaller the density of formation in the basin, the more obvious the effect of overpressure on the mechanical compaction of clastic reservoir. The results of porosity prediction in different types of sedimentary basins in three different epochs indicate that the errors of reservoir porosity predicted by the reservoir porosity prediction model established in this paper are lower than that of Gluyas and Cade equations and the errors of porosity prediction vary with the formation Age gets older and increases. The prediction error of the porosity of the clastic reservoir in the Cenozoic overpressured basin is less than 2% under the condition that the amount of the reservoir cement is less than 10%, while the prediction error of the reservoir porosity in the Mesozoic overpressured basin is more than 5%. The prediction model of clastic reservoir porosity under overpressure established in this paper is only suitable for the prediction of porosity in the later overpressure basin.