江汉盆地潜江凹陷古近系潜江组盐间非砂岩储层评价

EVALUATION OF NONSANDSTONE RESERVOIRS BETWEEN SALT BEDS OF THE PALEOGENE QIANJIANG FORMATION IN THE QIANJIANG DEPRESSION OF THE JIANGHAN BASIN

王国力 张永生 杨玉卿 漆智先

WANG Guo-li ZHANG Yong-sheng YANG Yu-qing QI Zhi-xian

中国石化集团, 科技开发部, 北京, 100029 2. 中国地质科学院, 矿产资源研究所, 北京, 100037 3. 中海油田服务股份有限公司, 北京, 101149 4. 中国石化, 江汉油田分公司, 湖北, 潜江, 433124

Department of Science & Technology Development, SINOPEC, Beijing 100029, China 2. Institute of Mineral Resources, Chinese Academy of Geological Sciences, Beijing 100037, China 3. WellTech-China Oilfield Services Ltd., Beijing 101149, China 4. Jianghan Oilfield Company, SINOPEC, Qianjiang, Hubei 433124, China

以Ⅳ级盐韵律(单个韵律尺度:几厘米到几十厘米,韵律组合可达几米)为基本尺度,对广泛分布于潜江凹陷的盐间(包括盐岩层内)非砂岩储层进行储集岩、储集空间、储集物性及储层纵向分布等方面的精细描述和研究,得出盐间相对淡化段中的Ⅳ级盐韵律及其组合是最有利、最有希望获得工业油流的储层。孔隙度受钙芒硝(Gb)含量的影响具体表现为:当钙芒硝的含量在10%～50%时,随其含量的增加,白云岩类和泥质岩类的孔隙度有所下降;而当其含量超过50%成为主要成分时,所形成钙芒硝岩的孔隙度则稳定在10%左右。在各类储集岩中,以白云岩类的孔隙度最高(平均达19%),泥质岩类次之(平均达13.4%),钙芒硝岩类最低(平均为10.6%),但渗透率却以泥质岩类最高(平均达68.8×10-3μm2),钙芒硝岩类次之(平均达36.2×10-3μm2),白云岩类最低(平均为25.3×10-3μm2),表明渗透率的高低不完全取决于孔隙度的大小,而主要与孔隙结构的分选性以及构造裂缝等有关。盐间非砂岩储层的孔吼半径普遍较小,大径孔喉仅占很小比例,渗透性普遍较差。因此,欲有效开发此类非砂岩储层,有必要根据盐类矿物的溶解习性,以改善渗透性为目标对储层作适当的改造以利开发。

Based on Ⅳ-order rhythms as the basic scale (scale: several to dozens of centimeters), the authors have, for the first time, made a detailed description and study of nonsandstone reservoirs between salt beds distributed widely in the Qianjiang subbasin, Jianghan basin, in respect to reservoir rock types, reservoir pore spaces, physical properties of reservoirs and vertical distribution of reservoirs and draw the following conclusions: Ⅳ-order rhythms and their association in relatively diluted intervals are the most promising reservoirs in which accumulations with industrial oil could occur. Among all types of reservoir rocks, dolostones have the highest porosity (average 19%) and lowest permeability (average 25.3×10-3μm2), mudstones have a medium porosity (average 13.4%) and the highest permeability (average 68.8×10-3μm2), and glauberite rock has the lowest porosity average 10.6%) and a medium permeability (average 36.2×10-3μm2). These data indicate that the permeability is not absolutely positive relative to the porosity but mainly relative to the pore texture and fractures. The porosity of reservoirs is influenced by the glauberite content. When the glauberite content is from 10% to 50%, the porosities of dolostones and mudstones decline with increasing glauberite content, and when the glauberite content is above 50%, glauberite forms glauberite rock and its porosity are maintained at about 10%. This suggests that the view that the porosity is positive relative to the glauberite content in dolostones is incorrect. Most nonsandstone reservoirs) between salt beds commonly have small pore throats and poor permeability. So if we want to develop) them effectively, it is necessary to improve their permeability according to the typical dissolution behaviors) of evaporite minerals.

https://doi.org/10.11781/sysydz200405462