致密砂岩储层不同成岩作用对孔隙度定量演化的影响:以鄂尔多斯盆地姬塬油田长6储层为例

doi:10.19657/j.geoscience.1000-8527.2018.03.10

摘要/Abstract

摘要：

鄂尔多斯盆地姬塬油田长6储层压实作用和成岩作用强烈,储层的强非均质性制约了油气勘探效益的提高。通过开展常规物性、图像粒度、铸体薄片、X衍射、扫描电镜、高压压汞和恒速压汞等实验研究储层的微观特征,以时间为主轴,综合沉积环境、埋藏深度、古地温、构造等因素,采用“成岩演化特征”和“地质综合效应”相结合的方法建立了姬塬油田长6致密砂岩储层的孔隙度演化模拟方程,分析了致密砂岩储层成岩作用、孔隙演化等的成因机理。孔隙度演化计算结果表明姬塬油田长6段致密砂岩储层初始孔隙度为37.33%,压实作用损失的孔隙度为22.47%,早期胶结-交代损失的孔隙度为3.69%,产生的次生孔隙度为6.53%,中晚期胶结-交代过程孔隙度损失平均值为6.97%,计算孔隙度平均值为10.06%。致密砂岩储层的差异性成岩演化过程是导致储层物性和微观孔隙结构差异的根本原因。

关键词: 姬塬油田, 长6储层, 致密砂岩, 差异性成岩, 孔隙度演化

Abstract:

In the Ordos Basin, the effects of compaction and diagenesis are strong in the Chang 6 reservoir of the Jiyuan Oilfield, and the great heterogeneity has limited the oil and gas development. This paper first studied the microscopic characteristics of the reservoir via microcosmic experiments including conventional physical properties, image granularity, casting lamella, X-ray diffraction, high-pressure mercury injection, constant speed mercury injection and SEM. Taking time as the main factor and integrating with the depositional environment, burial depth, paleotemperature, tectonism and other minor factors, we established the porosity evolution simulation equations of tight sandstone reservoir at Chang 6 by using the diagenetic evolution characteristics and geological comprehensive effects. We analyzed the formation mechanism of the diagenesis effect and porosity evolution in tight sandstone reservoirs. Computing results of porosity evolution show that the initial porosity of the Chang 6 reservoir was 37.33%, the porosity loss by compaction effect was 22.47%, porosity loss by early phase cement-metasomatism was 3.69%, secondary porosity was 6.53%, the porosity loss by middle and late phase cement-metasomatism was 6.97%, and the porosity was 10.06% on average. We suggest that the differential diagenetic evolution process of tight sandstone reservoir is the fundamental cause of the physical property differences and micro-pore structures.

Key words: Jiyuan Oilfield, Chang 6 reservoir, tight sandstone, differential diagenesis, porosity evolution

中图分类号:

TE122.2

黎盼, 孙卫, 杜堃, 黄何鑫, 白云云. 致密砂岩储层不同成岩作用对孔隙度定量演化的影响:以鄂尔多斯盆地姬塬油田长6储层为例[J]. 现代地质, 2018, 32(03): 527-536.

LI Pan, SUN Wei, DU Kun, HUANG Hexin, BAI Yunyun. Effect of Differential Diagenesis on the Quantitative Evolution of Porosity in Tight Sandstone Reservoirs: Taking the Chang 6 Reservoir of the Jiyuan Oilfield in Ordos Basin as An Example[J]. Geoscience, 2018, 32(03): 527-536.

图/表 11

图1 姬塬油田地理位置示意图

Fig.1 Map showing the location of the Jiyuan Oilfield

图2 姬塬油田长6储层砂岩分类图

Fig.2 Sandstone classification of the Chang 6 reservoir in the Jiyuan Oilfield

图3 姬塬油田长6储层碎屑成分含量图

Fig.3 Clastic rock compositions of the Chang 6 reservoir in the Jiyuan Oilfield

图4 研究区样品储层物性分布直方图

Fig.4 Histogram of physical distribution in the study area

表1 姬塬油田长6段储层孔隙度演化模拟方程[19??-22]

Table 1 Simulation equation of porosity evolution of the Chang 6 reservoir in the Jiyuan Oilfield

		各类参数	计算公式
		分选系数F 未固结砂岩孔隙度P₁	F=(D₂₅/D₇₅)/2 P₁=20.91+22.90/F
孔隙度演化模拟	压实作用为主	压实后剩余孔隙度P₂	P₂=P_a+(P_b+P_c)×P_d/P_e
		压实过程损失孔隙度Y₁	Y₁=P₁-P₂
		压实过程孔隙度损失率Z₁	Z₁=Y₁×100%/P₁
	胶结-交代作用为主	压实-胶结-交代后剩余孔隙度P₃	P₃=P₂-P_a
		胶结-交代过程损失孔隙度Y₂	Y₂=P₂-P₃
		胶结-交代过程孔隙度损失率Z₂	Z₂=Y₂×100%/P₁
	次生孔隙发育为主	溶蚀作用增加的孔隙度P₄	P₄=P_f×P_d/P_e
		自生晶间孔增加的孔隙度P₅	P₅=P_g×P_d/P_e
		微破裂作用产生的孔隙度P₆	P₆=P_h×P_d/P_e
		成岩作用产生的孔隙度P₇	P₇=P₄+P₅+P₆
		次生孔隙度增加率Z₃	Z₃=P₇×100%/P₁
		微孔率Z₄	Z₄=(P_i-P_e)×100%/P_i
	计算现今孔隙度P₈		P₈=P₃+P₇
	误差计算E		E=\|P_d-P₈\|×100%/P_d

表2 姬塬油田长6段储层不同成岩演化阶段孔隙度定量演化计算表

Table 2 Porosity evolution in the different diagenetic stages of the Chang 6 reservoir in the Jiyuan Oilfield

研究区	层位	参数类型	初始孔隙度/%	压实损失孔隙度/%	早期胶结-交代作用损失孔隙度/%	产生次生孔隙度/%	中晚期胶结- 交代作用损失孔隙度/%	计算孔隙度/%	气测孔隙度/%	相对误差/%
姬塬油田	长6	最大值	39.48	30.19	15.13	11.32	24.14	13.02	14.73	11.61
		平均值	37.33	22.47	3.69	6.53	6.97	10.06	10.65	7.98
		最小值	36.35	6.32	0.5	0	1.56	3.84	3.77	1.86

图5 长6段储层成岩演化过程中孔隙度的气测值与计算值之间相关关系

Fig.5 Relationships between gas survey porosity and calculated porosity of diagenetic evolution of the Chang 6 reservoir in the Jiyuan Oilfield

图6 姬嫄油田长6段储层H212井孔隙度演化模型

Fig.6 Porosity evolution model of well H212 of the Chang 6 reservoir in the Jiyuan Oilfield

图7 姬塬油田长6段储层孔隙度演化典型样品镜下特征 (a)强机械压实,压溶及硅质加大边,颗粒线接触,G46井,2 459.8 m;(b)强胶结发育,硅质加大,铁方解石充填孔隙,H222井,2 450.66 m;(c)强溶蚀,长石溶孔发育,高岭石充填孔隙,H48井,2 437.18 m;(d)粒间孔发育,绿泥石薄膜发育,发育粒缘及粒内长石溶蚀,H222井,2 450.66 m;(e)致密结构,硅质及长石质加大,残余粒间孔、颗粒溶孔发育,H210井,2 362.2 m;(f)叶片状绿泥石膜,粒表绿泥石黏土膜及粒间残余孔隙发育,H129井,2 361.42 m;(g)粒间溶蚀孔,伊利石搭桥式生长,自生石英充填残余孔,G80井,2 570.47 m;(h)粒间残余孔,石英、长石加大,画卷状伊利石充填残余孔喉,G65井,2 087.74 m

Fig.7 Microphotographs of the typical porosity evolution features of the Chang 6 reservoir in the Jiyuan Oilfield

图8 长6段储层孔隙度损失对比图

Fig.8 Comparison of porosity loss of the Chang 6 reservoir

表3 姬塬油田长6段储层成岩作用关键点孔隙度演化特征

Table 3 Porosity evolution characteristics in the diagenetic stages of the Chang 6 reservoir in the Jiyuan Oilfield

参数类型	代表样品		初始孔隙度/%	压实损失孔隙度/%	早期胶结- 交代作用损失孔隙度/%	产生次生孔隙度/%	中晚期胶结- 交代作用损失孔隙度/%	计算孔隙度/%	气测孔隙度/%	相对误差/%
参数类型	井号	深度/m	初始孔隙度/%	压实损失孔隙度/%	早期胶结- 交代作用损失孔隙度/%	产生次生孔隙度/%	中晚期胶结- 交代作用损失孔隙度/%	计算孔隙度/%	气测孔隙度/%	相对误差/%
最大压实率	G46	2 459.8	39.77	31.79	1.97	2.64	4.22	2.31	2.54	9.06
最大胶结率	H222	2 450.66	37.89	8.37	3.37	4.83	27.88	7.32	8.28	11.59
最大溶蚀率	H210	2 362.2	37.97	29.13	3.58	11.26	7.33	11.35	11.23	1.07
粒间孔最发育	G80	2 570.47	39.47	21.55	5.46	2.74	4.28	11.77	11.72	0.43

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