摘要
表生到埋藏成岩作用的温度与压力（４０～１００℃，常压～２５ＭＰａ），方解石、白云石相对含量不同的碳酸盐岩的溶蚀证明，在表生与相对浅埋藏的温压条件（低于７５℃、２０ＭＰａ）下，方解石的溶解速率大大超过白云石，随着温度和压力的升高，两者溶解速率的差值变小。在相对深埋藏的温压条件（高于７５℃、２０ＭＰａ）下，白云石的溶解速率已超过方解石，在１００、２５ＭＰａ的温压条件下，微晶白云石（白云石／方解石＝９８／２）的溶解速率已是含云灰岩（白云石／方解石＝１６／８４）的２倍，造成这种现象的原因是白云石的温度、压力效应大大超过方解石之故。根据实验的结果可以预测：表生与相对浅埋藏的温压条件下，石灰岩的岩溶作用较白云岩发育；但在深埋藏阶段，由溶解作用造成的白云岩次生孔隙应比方解石更为发育，这是埋藏深度大于２０００ｍ的地层中，白云岩储层多于石灰岩的重要原因。
Experiments of dissolution for carbonate with variable contents of calcite and dolomite have been performed under the temperature and pressure of epigenesis to burial diagenesis (40℃ ～ 100℃, normal atmospheric pressure ～ 25MPa ). In the Experments under the condition of simulating epigenesis and relatively shallow burial (T<75℃,P<20MPa), calcite dissolved much more quickly than dolomite. With the increase of temperature and pressure, the difference of dissolution rate between the two minerals decreases. When temperature is more than 75℃ and pressure more than 20MPa, the dissolution rate of dolomite exceeds calcite.Under the conditions of 100℃, 25MPa, the dissolution rate of dolomite (dolomite/calcite= 98/2) is two times of limestone (dolomite/calcite=16/86). The reason is that the temperature and pressure effect on dolomite being greater than that on calcite. Based on the results of experiments, it can be predicated that under the conditions of epigensis and relatively shallow burial environment limestone dissolution must develope more greatly than that of dolomite, but under the deep burial conditions, dolomite must have dissolved more quickly than that of calcite. This is one of the most important reasons for that there are more dolomite reservoir with secondary porosity than limestone in the strata deeper than 2000m.
出处
《沉积学报》
CSCD
北大核心
1995年第4期49-54,共6页
Acta Sedimentologica Sinica
基金
<油气藏地质及开发工程国家重点实验室>资助
关键词
碳酸盐岩
溶蚀
成岩作用
表生
温压条件
Experimental simulation
Epigenesis and burial diagenesis
Dissolution of dolomite
Composition of carbonate
Secondary porosity
