DEDOLOMITIZATION OF CARBONATE ROCKS IN ORDOS AND ITS RELATION TO RESERVOIR PROPERTY

Qin Jianxiong; Yang Zuosheng

doi:10.11743/ogg19970411

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DEDOLOMITIZATION OF CARBONATE ROCKS IN ORDOS AND ITS RELATION TO RESERVOIR PROPERTY
Vol. 18, Issue 4, Pages: 319-325(1997)
Online First：25 December 1997，

Published：1997
DOI： 10.11743/ogg19970411
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DOI：

Qin Jianxiong, Yang Zuosheng. DEDOLOMITIZATION OF CARBONATE ROCKS IN ORDOS AND ITS RELATION TO RESERVOIR PROPERTY[J]. 1997, 18(4): 319-325. DOI： 10.11743/ogg19970411.

摘要

鄂尔多斯下奥陶统碳酸盐岩储层去白云石化主要有下列类型:与不整合面有关的去白云石化主要是大气淡水沿不整合面运移

使其附近的铁白云石发生差异去白云石化

产生大量溶蚀组构和少量去白云石化方解石

以低Sr

具低温包裹体等为特征;埋藏环境中去白云石化是与缝合线、石膏结核、埋藏溶蚀孔洞缝和构造裂隙有关的类型

主要与Mg

的不断消耗、Ca

含量增加

及有机质热成熟作用和油气的运移聚集有关

以富Mg

低δ

包裹体均一温度高

可造成大量去白云石化方解石为特征。去白云石化白云岩孔隙度明显比其他类型白云岩和灰岩高

不仅可以提高储层的孔渗性

亦可使非渗透层变为高孔渗层。

Abstract

The dedolomitization of Lower Ordovician carbonate reservoirs in Ordos Basin could be divided into five types.Dedolonitization related to unconformity is characterized by producing lots of corrosion fabrics

small amounts of dedolomitized calcite with low contents of Sr

Mn and low homogenization temperature inclusions.Burial environment dedolomitization related to suture lines

gypsum nodules

burial dissolution caves and cracks

structure fissures are mainly resulted from the loss of Mg

the increase of Ca

the thermal maturation of organic matter and hydrocarbon migration and accumulation.The dedolomitization is charactorized by rich Mg

Sr and low δ

high homogenization temperature inclusions

thus forming large amounts of dedolamitized calcite.The porosity of the dedolomitized dolomite is clearly higher than that of other dolomites and limestones.This could not only improve reservoir permeability

but also change nonpermeable beds into permeable ones.