松辽盆地北部泉三、四段低渗透储层孔隙度演化史

为了预测松辽盆地北部泉三、四段储层的孔隙度、恢复孔隙演化史,本文综合考虑沉积相和成岩作用对储层孔隙度的影响,建立了孔隙度关于沉积相指数、成岩指数和深度等多因素非线性模型,预测了泉四段储层的孔隙度,恢复了孔隙演化史.结果表明,在泉四段储层填隙物高达16％的条件下,孔隙度预测的平均绝对误差仅为1.84％;在碎屑岩埋藏的早期,储层孔隙度主要受沉积相的影响,在晚期则受成岩作用的控制,次生孔隙主要发育在中成岩阶段A1亚期和A2亚期的早期；同一层位的储层孔隙度从古到今逐渐减小,在松辽盆地北部的主要成藏期(嫩江期末),中央坳陷泉四段Sq1的储层主要属于中～高孔隙度储层,有利于油气藏的形成,在明水组沉积的后期才变为致密储层.

Porosity Evolving History of Low Permeability Reservoirs in the Third and the Fourth Members of the Quantou Formation in the Northern Songliao Basin

In order to predict porosities of the low permeability reservoirs of the Third and the Fourth Members of the Quantou Formation in the Northern Songliao Basin and to restructure the porosity evolving history of these reservoirs,this study established a new multi-factors(including sedimentary facies index,diagenesis index and depth) non-linear model.The reservoir porosity of the Fourth Member of the Quantou Formation in the Northern Songliao Basin was predicted and the porosity evolving history was restructured using this new model.The results show that the averaged absolute error of the predicted porosities is 1.84% for the reservoirs with pore-filling rates up to 16%,and that the porosity was dominantly effected by sedimentary facies during the early burial time and was mainly controlled by diageneses during the late burial time,and that the secondary porosity was developed in stages of the middle diagenetic stage A1 and the early middle diagenetic stage A2,and that the porosity decreased gradually from ancient times to the present,and that the reservoir in the Sq1 of the Fourth Member of the Quantou Formation in the Central Depression was middle-high porosity reservoir at the time of oil and gas pool forming in the Northern Songliao Basin but became tight sandstones after the middle time of Mingshui Formation deposition.