玛湖凹陷二叠系下乌尔禾组含浊沸石砾岩孔隙度、渗透率实验测量新方法

New measurement method of porosity and permeability of laumontite bearing conglomerate of Permian lower Wuerhe formation in Mahu sag

浊沸石有利于砾岩原生孔隙的保护和溶蚀孔隙的形成,是玛湖凹陷斜坡区下乌尔禾组优质砂砾岩储层的主控因素之一.含浊沸石砾岩储层实验室测量的常规孔隙度、渗透率比核磁共振测井的孔隙度以及地质认识偏大较多,难以满足储的物性表征的需要.分析认为,制样不规整、浊沸石和黏土吸附水损失、常规压力与地层压力偏差大是主要影响因素,需要开发对应的实验室测量方法.首先,采用金刚石线切割制样获取了形状规则的柱塞样;其次,在62℃、45%相对湿度的恒温恒湿条件下测量了核磁共振、电阻率随烘干时间的变化,基于数据变化的拐点获得了保全浊沸石和黏土的吸附水状态的岩样;最后,对保全吸附水的岩样进行地层压力条件下的孔隙度、渗透率测量作为含浊沸石砾岩的孔隙度、渗透率.应用效果表明新方法确定的孔隙度、渗透率与产层的产液情况吻合较好.

Laumontite is one important factor for the high-quality reservoir because of its roles on the protection of original pore and the dissolution porosity.The porosities measured under normal condition are bigger than that of nuclear magnetic resonance log.Also,there is a deviation between the porosities and permeabilities measured under normal condition and geological cognition.It is believed that normal porosities and permeabilities could not be used for reservoir characterization because of nonstandard core plugs,loss of whole adsorbed water of laumontite and clay,and the difference between normal pressure and formation pressure.It is necessary to develop new method to get porosities and permeabilities for laumontite bearing conglomerate.First,a diamond wire cutting technology is used to get standard core plugs.Secondly,some core plugs with whole adsorbed water of laumontite and clay are gotten through a continuous measurement in which nuclear magnetic resonance and resistivity are measured every hour under the condition of constant temperature(62℃)and humidity(45%RH)to get the change point.At last,the porosities and permeabilities in situ of core plugs with whole adsorbed water are measured as the porosities and permeabilities of laumontite bearing conglomerate.The result shows that the porosities and permeabilities measured by new method match good to the production of reservoir.