Study on formation conditions of high-quality reservoir of Sinian Dengying Formation in central Sichuan
-
摘要: 为了弄清川中地区震旦系灯影组优质储层的形成条件,为该区油气的后期勘探和开发布署提供理论支持。以岩心观察、铸体薄片观察、地球化学测试资料、钻井资料和测井资料等生产测试资料为基础,对优质储层的形成条件进行综合分析,发现储集空间是由次生的孔、洞和缝组成,其中,沿藻纹层分布的溶孔、溶洞和溶缝是优质储层。研究表明优质储层是在沉积、成岩和构造共同作用下形成的,藻坪微相是基础,桐湾构造运动提供了必要的有利条件,表生岩溶作用是储层形成的关键。Abstract:
Central Sichuan is located at the eastern high point of the Leshan-Longnvsi ancient uplift axis. With a large amount of oil and gas resources, the Sinian Dengying Formation has a good exploration prospect. Since 2011 when CNPC deployed Well GS1 to explore Dengying Formation in the study area and then succeeded in discovering the oil and gas reservoirs, many scholars have done much research in this area and achieved a lot. But their opinions are similar only in terms of the understanding of lithology. In fact, multiple tectonic movements, the variable diagenetic environment and complex diagenesis of the Dengying Formation make it difficult for scholars to study the formation conditions of high-quality reservoirs in the Dengying Formation of the study area, which has resulted in a great controversy about the formation conditions of high-quality reservoirs. Therefore, taking the existing drilling cores and field profiles in central Sichuan and its adjacent areas as the main research objects, we studied the formation conditions of high-quality reservoirs in this paper, based on previous research as well as the testing data such as data from surveying wells and logging, and geochemical and physical properties. In this study, the existing drilling cores, field sections and rock slices in central Sichuan and its adjacent areas were analyzed for research of the rock types and reservoir space that constitute the reservoir. The results show that the lithology of Dengying Formation is mainly dolomite, with a small amount of mudstone and siliceous rock. There are many types of rock forming the reservoir, mainly including crystalline dolomite, sandy dolomite, algal laminated dolomite and karst breccia. The reservoir space is mainly composed of secondary pores, holes and fractures. The pores mainly include intercrystalline pores, intercrystalline dissolution pores, intergranular dissolution pores and residual intergranular pores. Among them intercrystalline pores and intercrystalline dissolution pores are mainly distributed in crystalline dolomite. In some parts, these two types of pores will be eroded and then expand into pore-type karst caves after karstification. However, intergranular dissolution pores and residual intergranular pores are mainly distributed in sandy dolomite, and the connectivity between them is poor. The caves mainly include "grape lace" caves, inter-gravel caves, and pore-type karst caves. The types of caves also include karst pores, caves and fissures that are distributed along the algal laminae. Among these caves, "grape lace" caves and inter-gravel caves are mainly distributed in breccia. Most of these two types of caves are filled with very small residual space. Pore-type karst caves are mainly distributed in crystalline dolomite. However, the dissolution pores, caves and fissures extending along the algal laminae are mainly distributed in the algal laminated dolomite. They are less affected by the later diagenesis and have weak infilling capacity, relative completeness and good connectivity. Fractures are mainly formed in a large number by tectonism and generally regarded as seepage channels rather than reservoir space for oil and gas. Finally, the existing research and comparison of the physical property different reservoir space show that the high-quality reservoir is composed of dissolution pores, caves and fractures distributed along the algal layer. The comprehensive study of the geological background of the study area indicates that the sedimentary facies of the study area are platforms. The subfacies are shallow water platforms and semi-deep water platforms, and the microfacies are shoal patches, cohesive shoals, algal flats, dolomitic flats and mud flats. At the same time, the correlation between lithology, reservoir space and sedimentary microfacies has been studied, showing that algal flats are the basis of high-quality reservoir development. The formation of reservoirs in Dengying Formation is mainly under the effect of recrystallization and karstification. Recrystallization can only improve the permeability of the reservoir, but cannot increase the effective reservoir space. Karstification took place during syngenetic-quasisyngenetic stage, supergene stage and buried-rock stage. In the syngenetic-quasisyngenetic stage, karstification mainly formed selective karst pores and caves, but rarely remained. Karstification in the supergene stage mainly formed karst pores, caves and fractures distributed along the algal laminae, which provided high-quality reservoir space. Buried karstification mainly occurred in the process of generation and degradation of oil and gas, and the overall transformation degree is small, but the connectivity and permeability of the reservoir space were improved. Therefore, supergene karstification plays a key role in the formation of high-quality reservoirs. In the study area, high-quality reservoirs are formed under the joint action of sedimentation, diagenesis and tectonism. According to the formation process of high-quality reservoirs, different periods and different pore structure characteristics, their evolution process can be divided into five parts: sedimentary period, shallow-burial period, supergene period, medium-deep burial period and period showing current characteristics. The study on evolution characteristics of high-quality reservoirs in different periods show that algal flats are the foundation for the formation of high-quality reservoirs; the Tongwan tectonic movement provides necessary conditions; supergene karstification is the key. -
Key words:
- central Sichuan /
- Sinian /
- Dengying Formation /
- high-quality reservoir /
- forming conditions
-
0. 引 言
川中地区位于乐山—龙女寺古隆起轴部的东部高点位置[1](图1),灯影组中含有大量的油气资源[2-4]。2011年,中石油集团公司在该区部署了GS1井对灯影组中的油气资源进行勘探,获得了成功,发现了灯影组中的大气藏。因此,许多学者[5-8]在该区进行了大量的研究,结果仅在岩性的认识上,意见较为统一,认为灯影组中的泥岩和硅质岩的含量较少,白云岩的含量占有绝对的优势,且富藻,同时根据岩性和藻含量的特征,进行了地层划分,将灯影组分成了四段(图1),其中灯三段(Z2d3)的岩性为泥岩和硅质岩,灯二段(Z2d2)和灯四段(Z2d4)中藻的含量较高,且储层较为发育。事实上,灯影组形成的时代古老,成岩环境多变,成岩作用异常复杂,从而导致对优质储层的形成条件的争议较大,一部分学者认为灯影组是碳酸盐岩台地和混积台地的产物,优质储集空间的形成主要受颗粒滩和丘滩复合体所控制[6];一部分学者认为灯影组是碳酸岩台地的产物,优质储集空间的形成主要受颗粒滩控制[7]。
因此,本文在前人的研究基础之上,以川中地区及邻区已有的钻井岩心和野外剖面为主要研究对象,同时结合测井、录井和地球化学等测试资料,对优质储层的形成条件展开研究,希望能为该区后期的油气勘探和开发井位的部署提供理论支撑。
1. 优质储集空间
岩性是储层研究的基础,它对储层的分布和发育具有重要的影响因素[5]。通过对川中地区和邻区已有的钻井岩心、野外剖面以及铸体岩石薄片,并结合测井和录井资料,进行系统研究,结果表明,在研究区内,灯影组的岩性主要由白云岩组成,而硅质岩和泥岩的含量较少;构成储层的岩石类型主要由晶粒白云岩(图2a,b)、沙屑白云岩(图2c)和藻叠层白云岩(图2d)以及角砾岩(图2e,f)构成。
图 2 川中地区震旦系灯影组中储层的岩石类型与储集空间类型a. 晶粒(泥晶)白云岩,发育晶间孔, MX8井,5 290.00 m,×5(-) b. 晶粒(细晶)白云岩,发育晶间溶孔,AP1井,5 036.33 m,×5 (-) c. 沙屑白云岩,发育粒间溶孔与粒间孔,MX8井,5 309.00 m,×5(-) d. 藻叠层白云岩,发育沿藻纹层分布的溶孔、溶洞和溶缝,MX8井,5 114.54 m e. 角砾岩,发育砾间洞,Z6井,3 711.08 m f. 角砾岩,发育 “葡萄花边”洞,Z6井,3 733.20 m g. 粉晶云岩,发育孔隙型溶洞,GS2井,5 389.09 m h. 裂缝,MX8井,5112.05 mFigure 2. The reservoir rock types and reservoir space types of Sinian Dengying Formation in central Sichuana. Crystalline (micrite) dolomite develops intercrystalline pores, MX8 well, 5,290.00 m,×5(-) b. Crystalline (fine crystalline) dolomite develops intercrystalline dissolution pores, AP1 well, 5,036.33 m, ×5 (-) c. Sandy dolomite develops intergranular dissolution pores and intergranular pores, MX8 well, 5,309.00 m,×5(-) d. algal laminated dolomite develops karst pores, caves and fissures that are distributed along the algal laminae, MX8 well, 5,114.54 m e. Breccia develops inter-gravel caves, Z6 well, 3,711.08 m f. Breccia develops "grape lace" caves, Z6 well, 3,733.20 m g. Powder crystal dolomite develops pore-type karst caves, GS2 well, 5,389.09 m h. Fissure, MX8 well, 5,112.05 m 5,112.05 m灯影组中的原生孔隙已经被破坏殆尽,这是因为灯影组经历了多期构造运动,成岩环境多变,成岩作用复杂所导致的;通过对已有的样品研究表明,现今的储集空间类型具有多样性,主要是由次生形成的孔、洞和缝组成,其特征如下:
孔主要包括晶间孔(图2a)、晶间溶孔(图2b)、粒间溶孔(图2c)以及残余的粒间孔(图2c);其中晶间孔和晶间溶孔主要分布在晶粒白云岩,在局部,这些孔隙经岩溶作用后,会被溶蚀扩大,变成孔隙型溶洞;而粒间溶孔和残余的粒间孔主要分布在砂屑白云岩中,但是这些沙屑白云岩通常以孤立的“团块”状形式存在,且彼此间的关联性差,导致粒间溶孔和残余的粒间孔整体之间的连通性也较差。
洞主要包括“葡萄花边”洞(图2e)、砾间洞(图2f)、孔隙型溶洞(图2 g)以及沿藻纹层分布的溶孔、溶洞和溶缝(图2d);其中“葡萄花边”洞(图2e)和砾间洞(图2f)主要分布在角砾岩中,多位于灯二段和灯四段的顶部,在上覆地层的充填和压实作用影响下,特别是充填作用,导致绝大部分洞隙空间被充填,残余空间极小;孔隙型溶洞(图2 g)主要分布在晶粒白云岩中;而沿藻纹层分布的溶孔、溶洞和溶缝主要分布在藻叠层白云岩中,受后期的成岩作用影响较小,充填作用微弱,保存较为完整,且彼此的连通性较好。
缝主要是由构造作用形成,灯影组经历了多期构造运动,形成了大量的裂缝,产状具有多样性,但是这些裂缝通常主要是用作油气的渗流通道,而不是油气的储集空间,且常和孔、洞而伴随存在,形成组合空间(裂缝型溶孔与裂缝型溶洞)(图2 h)[5]。
物性是判断优质储层的主要标准,在物性实验测试中,沿藻纹层分布的溶孔、溶洞和溶缝的孔隙度和渗透率都 达到了碳酸盐中是优质储层标准[9-10],其它类型的储集空间则相对较差。因此表明在该区灯影组中的优质储集空间是沿藻纹层分布的溶孔、溶洞和溶缝构成。
2. 优质储层形成的条件
2.1 藻坪是优质储层形成的基础
沉积相是储层形成的基础[11-13]。在震旦世灯影期,大扬子台坪在绝大部分时期都于浅水台坪环境中,沉积水体较浅[13],且地形起伏小,潮汐作用改造能力较弱,且在较短时期内,可快速沉降到浪基面以下,转变为半深水台坪。从研究区所处的构造位置看,正好位于扬子台坪的中间(图3),沉积产物主要受浅水台坪的沉积环境控制。因此,根据在沉积环境和沉积产物的特征,可将研究区在灯影期的沉积相认定为台坪(表1),同时可以进一步划分为浅水台坪和半深水台坪两种亚相以及点滩、粘连滩、藻坪、云坪和泥坪五种微相。在不同的沉积微相中,岩性特征、储集空间类型和储层的厚度各不相同(表1)。
表 1 川中地区灯影组沉积微相、沉积微相中的岩性特征和储集空间类型关系表(据周正[9])Table 1. Division of sedimentary facies of Dengying Formation, lithologic characteristics and reservoir space types of different sedimentary microfacies in central Sichuan (According to ZHOU Zheng modified[9])储集空间类型 岩性 微相 亚相 沉积相 粒间(溶)孔 砂(砾)屑云岩 点滩 浅水台坪 台坪 储集空间不发育 颗粒粘连白云岩 粘连滩 顺藻纹层方向的
溶孔、溶洞和溶缝藻叠层白云岩 藻坪 晶间孔和晶间溶孔 晶粒白云岩 云坪 半深水台坪 储集空间不发育 硅质岩,泥岩 泥坪 从表1和图4中可以看出,在云坪中发育晶粒白云岩,晶间孔和晶间溶孔是主要的储集空间,分布的面积较大,但储层厚度较小;在藻坪中发育藻叠层白云岩,分布面积次之,储集空间为沿藻纹层分布的溶孔、溶洞和溶缝,且储层的厚度较大;在点滩中,岩性为砂屑云岩,且点滩是以孤立团块形式存在,彼此的连通性较小,分布的面积最小;而在粘连滩和泥坪中很少有孔隙空间存在。不难看出,优质储层的厚度和分布均受藻坪控制,因此,藻坪是优质储层形成的基础。
2.2 在优质储层形成过程中,表生岩溶作用是关键
在灯影组的储层形成过程中,重结晶作用和岩溶作用起着十分重要的作用[9-14]。
许多学者对灯影组中的白云岩成因进行了大量研究,其结果认为是原生成因的[15]。若原生成因的白云岩,其白云石的晶体应为泥晶或微晶。事实上,有大量的晶粒粗大的白云石存在(表3,2~7号样品),这应是重结晶作用的结果[16]。灯影在经重结晶作用后,泥晶或微晶白云石中的86Sr会发生流失,形成的晶粒粗大的粉晶和细晶白云石,其中87Sr/86Sr的值会增大,有序度的值也会增大,其储集空间依旧是晶间孔,且总的空间体积未发生改变,但彼此连通性获得了改善,有效的提高了渗透率[10]。
表 3 川中地区灯影组白云岩中锶、碳和氧同位素和有序度特征Table 3. Characteristics of strontium, carbon and oxygen isotopes and ordering degree of dolostones from Dengying Formation in central Sichuan样品编号 岩性 87Sr/86Sr δ18C/‰ δ18O/‰ 有序度 1 泥晶白云岩 0.708 58 −0.151 −8.221 0.503 1 2 粉晶白云岩 — −0.413 −7.458 0.646 7 3 粉晶白云岩 0.708 89 1.501 −7.825 — 4 细粉晶白云岩 0.708 92 0.315 −7.559 0.705 2 5 细粉晶白云岩 — 0.156 −7.608 — 6 细晶白云岩 — 0.465 −7.873 — 7 细晶白云岩 0.708 97 0.446 −7.878 0.867 3 8 溶缝渗流豆
(白云石)— 0.091 −8.718 — 9 溶缝渗流豆
(白云石)— −1.309 −9.869 — 研究区灯影组在同生—准同生期、表生期和埋藏期均受到了岩溶作用的改造[5,9,14],但改造程度各不相同。
在同生—准同生期,主要是在滩和藻坪微相中发生选择性岩溶作用[16],形成一些小型溶沟和粒内溶孔等,在后期的压实和胶结等破坏性成岩作用的改造下,导致只有极少部分的孔隙空间被保存下来[10,16],因此,在同生—准同生期形成的孔隙空间对当今的储层没有直接贡献。
表生期岩溶作用主要发生在震旦世末期,发生桐湾构造运动,导致扬子台坪被整体抬升[17~20],而研究区正好位于杨子台坪的中间位置,导致其两度被抬升且暴露在大气淡水之中。
大气淡水对碳酸盐岩的改造特征通常是利用碳、氧同位素来进行研究[5,10],在表3中,基岩样品(1~7号)的δ13C为−0.413‰~1.501‰,平均值是0.331‰,δ18O为−8.221‰~−7.458‰,平均值是−7.774‰。而溶缝中渗流豆(8~9号)的δ13C为−1.309‰~0.091‰,平均值是−0.609‰;δ18O为−9.869‰~−−8.718‰,平均值是−9.293‰。通过对比,不难看出,δ13C和δ18O的值偏负的是渗流豆,而基岩则偏正,表明表生岩溶作用对灯影组进行了强烈的改造。
在研究区内,表生岩溶作用对灯影组的溶蚀改造在研究区MX8井灯四段的岩心剖面(图5)中能够得到很好的体现,从图5中可以看出,表生岩溶作用主要发生在距顶部0~200 m内,根据岩溶作用的强弱和储集空间的类型,可以将其分为3个岩溶带[7]:垂直渗流带、水平潜流带和深部缓流带。
垂直渗流带中的岩性为晶粒白云岩,是云坪微相的产物。在重力作用下,大气淡水沿竖直方向进行运移,在运移过程中,会对运移通道周围的白云岩进行溶蚀,形成高角度的溶沟和溶缝,同时产生了大量的角砾岩,在角砾间会形成一些砾间洞。但是这些孔隙空间在后期沉积的上覆地层(筇竹寺组)的影响下,绝大部分被充填破坏(图6a~c)。但是在被充填破坏之前,这些孔隙空间为大气淡水的向下运移,溶蚀下覆岩层,提供了运移通道,促进了下覆优质储层的形成。
图 6 砾间洞、溶沟和溶逢的充填特征及有机酸对孔隙空间的溶蚀改造特征a- 砾间洞被上覆的沉积产物充填,AP1丼,5 035.90 m b- 溶沟被上覆的沉积产物充填,GS1丼,4 980.10 m c- 溶缝被渗流粉沙充填,GS1丼,4 906.60 m d-有机酸沿孔隙空间的溶蚀,Z4丼,4491.33 mFigure 6. Infilling characteristics of intergranular cavity, dissolution ditch and dissolution fracture and the characteristics of corrosion transformation of organic acid on pore spacea- Inter-gravel caves are filled with overlying sedimentary product, AP1 well, 5,035.90 m b- Dissolution ditches are filled with overlying sedimentary product, GS1 well, 4,980.10 m c- Fissures are filled with seepage silty sand, GS1 well, 4,906.60 m d- Corrosion of organic acid on pore space, Z4 well, 4,491.33 m潜流带的岩性为藻叠层白云岩,是藻坪微相的产物。大气淡水经垂直渗流带后,进入潜流带,主要沿着早期藻死亡后留下的空间进行流动,在运移过程中,会对运移通道周围的岩石进行强烈的溶蚀改造,使其演变成为沿藻纹层分布的溶孔、溶洞和溶缝。尽管经历了多期构造运动和不同类型成岩作用的改造,影响较小,几乎全部被保存下来[11],成为当今的优质储集空间。
深部缓流带的岩性为白云岩,原始孔隙空间不发育,尽管潜流带中的部分大气淡水会进入部分孔隙中,但是流动极为缓慢,几乎是停留在原地,溶蚀改造的强度弱,从而导致该岩溶带中的孔隙空间极不发育。
埋藏期岩溶作用是因为油气产生和降解过程中,均会产生大量的有机酸,从而对早期的孔隙空间进行溶蚀改造。在志留纪末期至二叠纪前,为有机质的成熟期;在侏罗纪,为石油的降解期。在这个两个时期,均有大量的有机酸产生,对早期的孔隙空间进行了溶蚀改造(图6d),总体上的改造程度较小,但储集空间的连通性和渗透率均得到了提升。
不难看出,在研究区内灯影组中,表生岩溶作用对藻叠层白云岩进行改造的结果是形成了优质储集空间,因此,表生岩溶作用是优质储层形成的关键;而桐湾构造运动导致研究区两度被抬升暴露于大气淡水中,促进了表生岩溶作用的发生,为优质储层的形成提供了必要的有利条件
3. 优质储层形成的演化过程
在研究区内,灯影组中的优质储层是逐渐演化形成的,根据形成过程和孔隙结构的演化特征,可以将其划分为沉积期、浅埋藏期、表生期、中-深埋藏期和当今特征五个演化阶段(图7)[9.16],在不同的演化阶段中,孔隙结构特征不同。
在沉积期,沉积的水体相对较浅,藻类十分发育,这些藻类会吸附大量的白云石和岩屑,从而形成藻叠层白云岩,其孔隙主要为粘连格架孔,整体较为疏松,总的孔隙度在70%左右[5](图7)。
在浅埋藏期,灯影组的上覆沉积物会这些对格架孔产生强烈的压实作用,使其几乎消失殆尽,孔隙度急剧降低;但是在藻类消亡之后,其分布的层位则留有一些的孔隙空间,为大气淡水运移提供了良好的通道。
在表生期,因桐湾构造运动导致灯影组两度暴露在大气淡水中,同时大气淡水中含有CO2,呈酸性,会沿着藻死亡后提供的运移通道进行流动,发生表生岩溶作用,会对这些通道周围的岩石进行溶蚀改造,使其形成沿藻纹层分布的溶孔、溶洞和溶缝,孔隙度和连通性都较好,总体上看,总的孔隙空间增加至10%[5](图7)。
在中—深埋藏期,上覆地层的沉积产物会对沿藻纹层分布的溶孔、溶洞和溶缝产生压实作用,同时还会受到胶结、充填和埋藏溶蚀等成岩作用的影响,但是这些孔隙空间总体上受到的影响较小,绝大部分被保存下来。总体上看,储层总孔隙度变化较小。
在当今,对研究区及邻区灯影组中已有的钻井岩心和野外剖面等资料进行观察研究表明,优质储集空间(沿藻纹层分布的溶孔、洞和缝)尽管经过中—深埋藏期成岩过程中的多期成岩作用的影响,其总的改造程度较小,其基本特征与表生期基本一致,但总的孔隙度略有降低。
因此,从以上的分析可以看出,优质储层(沿藻纹层分布的溶孔、洞和缝)是在沉积、成岩和构造运动的共同作用下形成的,其中藻坪是基础,桐湾构造运动提供了必要的有利条件,表生岩溶作用是关键。
4. 结 论
(1)在灯影组中,储集空间由次生的孔、洞和构造作用形成的裂缝组成,其中优质储层是由沿藻纹层分布的溶孔、溶洞和溶缝构成;
(2)在灯影组中,优质储层是在沉积、构造和成岩等共同作用下形成的,在其形成的演化过程中,藻坪微相是基础,桐湾构造运动提供了必要的有利条件,表生岩溶作用是关键。
-
图 2 川中地区震旦系灯影组中储层的岩石类型与储集空间类型
a. 晶粒(泥晶)白云岩,发育晶间孔, MX8井,5 290.00 m,×5(-) b. 晶粒(细晶)白云岩,发育晶间溶孔,AP1井,5 036.33 m,×5 (-) c. 沙屑白云岩,发育粒间溶孔与粒间孔,MX8井,5 309.00 m,×5(-) d. 藻叠层白云岩,发育沿藻纹层分布的溶孔、溶洞和溶缝,MX8井,5 114.54 m e. 角砾岩,发育砾间洞,Z6井,3 711.08 m f. 角砾岩,发育 “葡萄花边”洞,Z6井,3 733.20 m g. 粉晶云岩,发育孔隙型溶洞,GS2井,5 389.09 m h. 裂缝,MX8井,5112.05 m
Figure 2. The reservoir rock types and reservoir space types of Sinian Dengying Formation in central Sichuan
a. Crystalline (micrite) dolomite develops intercrystalline pores, MX8 well, 5,290.00 m,×5(-) b. Crystalline (fine crystalline) dolomite develops intercrystalline dissolution pores, AP1 well, 5,036.33 m, ×5 (-) c. Sandy dolomite develops intergranular dissolution pores and intergranular pores, MX8 well, 5,309.00 m,×5(-) d. algal laminated dolomite develops karst pores, caves and fissures that are distributed along the algal laminae, MX8 well, 5,114.54 m e. Breccia develops inter-gravel caves, Z6 well, 3,711.08 m f. Breccia develops "grape lace" caves, Z6 well, 3,733.20 m g. Powder crystal dolomite develops pore-type karst caves, GS2 well, 5,389.09 m h. Fissure, MX8 well, 5,112.05 m 5,112.05 m
图 6 砾间洞、溶沟和溶逢的充填特征及有机酸对孔隙空间的溶蚀改造特征
a- 砾间洞被上覆的沉积产物充填,AP1丼,5 035.90 m b- 溶沟被上覆的沉积产物充填,GS1丼,4 980.10 m c- 溶缝被渗流粉沙充填,GS1丼,4 906.60 m d-有机酸沿孔隙空间的溶蚀,Z4丼,4491.33 m
Figure 6. Infilling characteristics of intergranular cavity, dissolution ditch and dissolution fracture and the characteristics of corrosion transformation of organic acid on pore space
a- Inter-gravel caves are filled with overlying sedimentary product, AP1 well, 5,035.90 m b- Dissolution ditches are filled with overlying sedimentary product, GS1 well, 4,980.10 m c- Fissures are filled with seepage silty sand, GS1 well, 4,906.60 m d- Corrosion of organic acid on pore space, Z4 well, 4,491.33 m
表 1 川中地区灯影组沉积微相、沉积微相中的岩性特征和储集空间类型关系表(据周正[9])
Table 1. Division of sedimentary facies of Dengying Formation, lithologic characteristics and reservoir space types of different sedimentary microfacies in central Sichuan (According to ZHOU Zheng modified[9])
储集空间类型 岩性 微相 亚相 沉积相 粒间(溶)孔 砂(砾)屑云岩 点滩 浅水台坪 台坪 储集空间不发育 颗粒粘连白云岩 粘连滩 顺藻纹层方向的
溶孔、溶洞和溶缝藻叠层白云岩 藻坪 晶间孔和晶间溶孔 晶粒白云岩 云坪 半深水台坪 储集空间不发育 硅质岩,泥岩 泥坪 表 3 川中地区灯影组白云岩中锶、碳和氧同位素和有序度特征
Table 3. Characteristics of strontium, carbon and oxygen isotopes and ordering degree of dolostones from Dengying Formation in central Sichuan
样品编号 岩性 87Sr/86Sr δ18C/‰ δ18O/‰ 有序度 1 泥晶白云岩 0.708 58 −0.151 −8.221 0.503 1 2 粉晶白云岩 — −0.413 −7.458 0.646 7 3 粉晶白云岩 0.708 89 1.501 −7.825 — 4 细粉晶白云岩 0.708 92 0.315 −7.559 0.705 2 5 细粉晶白云岩 — 0.156 −7.608 — 6 细晶白云岩 — 0.465 −7.873 — 7 细晶白云岩 0.708 97 0.446 −7.878 0.867 3 8 溶缝渗流豆
(白云石)— 0.091 −8.718 — 9 溶缝渗流豆
(白云石)— −1.309 −9.869 — -
[1] 魏国齐, 杨威, 杜金虎, 徐春春, 邹才能, 谢武仁, 武赛军, 曾富英. 四川盆地高石梯—磨溪古隆起构造特征及对特大型气田形成的控制作用[J]. 石油勘探与开发, 2015, 42(3):257-265.WEI Guoqi, YANG Wei, DU Jinhu, XU Chunchun, ZOU Caineng, XIE Wuren, WU Saijun, ZENG Fuying. Tectonic features of Gaoshiti-Moxi paleo-uplift and its controls on the formation of a giant gas field, Sichuan basin, SW China[J]. Petroleum Exploration and Development, 2015, 42(3):257-265. [2] 洪海涛, 包强, 张光荣. 对四川盆地天然气资源的潜在接替层系—震旦、寒武系有利目标区块的评价[J]. 成都理工学院学报, 2000, 27(14):143-146.HONG Haitao, BAO Qiang, ZHANG Guangrong. Evaluation of the favorable target areas for natural gas exploration in the Sinian and Cambrian systems in Sichuan basin[J]. Journal of Chengdu University of Technology, 2000, 27(14):143-146. [3] 张声瑜, 唐创墓. 四川盆地灯影组区域地质条件及含气远景[J]. 天然气工业, 1986, 6(1):3-9.ZHANG Shengyu, TANG Chuangmu. RegionaI geology conditions of Dengying Formation (Sinian) in Sichuan basin and its gas prospects[J]. Natural Gas Industry, 1986, 6(1):3-9. [4] 魏国齐, 杨威, 谢武仁, 金惠, 苏楠, 孙爱, 沈珏红, 郝翠果. 四川盆地震旦系—寒武系天然气成藏模式与勘探领域[J]. 石油学报, 2018, 39(12):1317-1327.WEI Guoqi, YANG Wei, XIE Wuren, JING Hui, SU Nan, SUN Ai, SHEN Juehong, HAO Cuiguo. Accumulation modes and exploration modes and exploration domains of Sinian-Cambrian natural gas in Sichuan basin[J]. Acta Petrolei Sinica, 2018, 39(12):1317-1327. [5] ZHOU Zheng, WANG Xingzhi, YIN Ge, YUAN Shuseng, ZENG Shejiao. Characteristics and genesis of the (Sinian) Dengying Formation reservoir in central Sichuan, China[J]. Journal of Natural Gas Science and Engineering, 2016, 29:311-321. doi: 10.1016/j.jngse.2015.12.005 [6] 李凌, 谭秀成, 曾伟, 周涛, 杨雨, 洪海涛, 罗冰, 边立曾. 四川盆地震旦系灯影组灰泥丘发育特征及储集意义[J]. 石油勘探与开发, 2013, 40(6):666-673.LI Ling, TAN Xiucheng, ZENG Wei, ZHOU Tao, YANGA Yu, HONG Haitao, LUO bing, BIAN Lizeng. Development and reservoir significance of mud mounds in Sinian Dengying Formation, Sichuan basin[J]. Petroleum Exploration and Development, 2013, 40(6):666-673. [7] 莫静, 王兴志, 冷胜远, 林刚, 熊剑文, 谢林, 周正. 川中地区震旦系灯影组储层特征及其主控因素[J]. 中国地质, 2013, 40(5):1505-1514.MO Jing, WANG Xingzhi, LENG Shengyuan, LIN Gang, XIONG Jianwen, XIE Lin, ZHOU Zheng. Reservoir characteristics and control factors of Sinian Dengying Formation in central Sichuan[J]. Geology in China, 2013, 40(5):1505-1514. [8] 毛琼, 邹光富, 张洪茂, 金辉, 黄海波. 四川盆地动力学演化与油气前景探讨[J]. 天然气工业, 2006, 26(11):7-10.MAO Qiong, ZOU Guangfu, ZHANG Hongmao, JIN Hui, HUANG Haibo. Discussion on geodynamic evolution and oil/gas prospect of the Sichuan basin[J]. Natural Gas Industry, 2006, 26(11):7-10. [9] 周正. 川中地区震旦系灯影组储层特征[D]. 成都: 西南石油大学, 2016.ZHOU Zheng. Characteristics of the (Sinian) Dengying Formation reservoir in central Sichuan, China[D]. Chengdu: Southwest Petroleum University, 2016. [10] 周正, 王兴志, 谢林, 莫静, 张杰. 川中地区震旦系灯影组储层特征及物性影响因素[J]. 天然气地球科学, 2014, 25(5):701-708.ZHOU Zheng, WANG Xingzhi, XIE Lin, MO Jing, ZHANG Jie. Reservoir features and physical influences of the Sinian Dengying Formation in central Sichuan, China[J]. Natural Gas Geoscience, 2014, 25(5):701-708. [11] 强子同. 酸盐岩储层地质学[M]. 东营: 中国石油大学出版社, 2007: 35-80QIANG Zitong. Carbonate Reservior Geology[M]. Dongying: China Universtiy of Petroleum Press, 2007: 35-102 [12] 焦伟伟, 李建交, 田磊. 中国海相碳酸盐岩优质储层形成的地质条件[J]. 地质科技情报, 2009, 28(6):64-68.JIAO Weiwei, LI Jianjiao, TIAN Lei. Geological conditions of marine carbonate high-quality reservoir in China[J]. Geological Science and Technology Information, 2009, 28(6):64-68. [13] 薛耀松, 唐天福, 俞从流. 中国南方上震旦统灯影组中的古喀斯特洞穴磷岩[J]. 沉积学报, 1992, 10(3):145-153.XUE Yaosong, TANG Tianfu, YU Congliu. Ancient karst cave phosphates from the upper Sinian Dengying Formation, Southern China[J]. Acta Sedimentologica Sinica, 1992, 10(3):145-153. [14] 杨家静. 四川盆地乐山—龙女寺古隆起震旦系油气藏形成演化研究[D]. 成都: 西南石油学院, 2002.YANG Jiajing, Study on formation and evolution of Sinian petroleum pools in Leshan-Longnvsi paleouplift, Sichuan basin[D]. Chengdu: Southwest Petroleum University, 2002. [15] 王士峰, 向芳. 资阳地区震旦系灯影组白云岩成因研究[J]. 岩相古地理, 1999, 19(3):21-28.WANG Shifeng, XIANG Fang. The origin of the dolostones from the dolostones from the Sinian Dengying Formation in the Ziyang district, Sichuan[J]. Sedimentary Facies and Palaeogeography, 1999, 19(3):21-28. [16] 王兴志, 穆曙光, 方少仙, 黄继祥, 侯方浩. 四川盆地西南部震旦系白云岩成岩过程中的孔隙演化[J]. 沉积学报, 2000, 18(4):550-554.WANG Xingzhi, MU Shuguang, FANG Shaoxian, HUANG Jixiang, HOU Fanghao. Evolution of porosity in the process of Sinian dolostone diagenesis in southwest Sichuan[J]. Acta Sedimenlologica Sinica, 2000, 18(4):550-554. [17] 汪泽成, 姜华, 王铜山, 鲁卫华, 谷志东, 徐安娜, 杨雨, 徐兆辉. 四川盆地桐湾期古地貌特征及成藏意义[J]. 石油勘探与开发, 2014, 41(3):305-312.WANG Zecheng, JIANG Hua, WANG Tongshan, LU Weihua, GU Zhidong, XU Anna, YANG Yu, XU Zhaohui. Paleo-geomorphology formed during Tongwan tectonization in Sichuan basin and its significance for hydrocarbon accumulation[J]. Petroleum Exploration and Development, 2014, 41(3):305-312. [18] 罗冰, 杨跃明, 罗文军, 文龙, 王文之, 陈康. 川中古隆起灯影组储层发育控制因素及展布[J]. 石油学报, 2015, 36(4):416-426.LUO Bing, YANG Yueming, LUO Wenjun, WEN Long, WANG Wenzhi, CHEN Kang. Controlling factors and distribution of reservoir development in Dengying Formation of paleo-uplift in central Sichuan basin[J]. Acta Petrolei Sinica, 2015, 36(4):416-426. [19] 文龙, 王文之, 张健, 罗冰. 川中高石梯—磨溪地区震旦系灯影组碳酸盐岩岩石类型及分布规律[J]. 岩石学报, 2017, 33(4):1285-1294.WEN Long, WANG Wenzhi, ZHANG Jian, LUO Bing. Classification of Sinian Dengying Formation and sedimentary evolution mechanism of Gaoshiti-Moxi area in central Sichuan basin[J]. Acta Petrologica Sinica, 2017, 33(4):1285-1294. [20] 闫海军, 彭先, 夏钦禹, 徐伟, 罗文军, 李新豫, 张林, 朱秋影, 朱迅, 刘曦翔. 高石梯—磨溪地区灯影组四段岩溶古地貌分布特征及其对气藏开发的指导意义[J]. 石油学报, 2020, 41(6):658-752.YAN Haijun, PENG Xian, XIA qinyu, XU Wei, LUO Wenjun, LI Xinyu, ZHANG Lin, ZHU Qiuying, ZHU Xun, LIU Xixiang. Distribution features of ancient karst landform in the fourth member of the Dengying Formation in the Gaoshiti-Moxi region and its guiding significance for gas reservoir development[J]. Acta Petroei Sinica, 2020, 41(6):658-752. -