Characteristics and main controlling factors of fracture development in the Ordovician carbonate reservoir, Tahe oilfield

doi:10.13745/j.esf.sf.2024.6.18

Abstract

Abstract:

The characteristics of natural fractures in Ordovician carbonate reservoirs, Tahe oilfield are systematically studied and the main controlling factors of fracture development are analysed using different experimental methods. Natural fractures can be divided into four types and seven subtypes: structural (tensile, shear), superficial (weathering), diagenetic (stylolites, bedding), and composite genetic (structural-weathering, structural-diagenetic), with structural being the dominating type. Fractures are mainly oriented NE-SW, NW-SE and NNE-SSW and dip toward NNW, NE and SEE, with dip angles mostly greater than 70° and fracture density ranging from 1.5 to 3.5 m^-1. According to filling characteristics and fracture cross-cutting relationships fracture filling can be divided into three stages. Fractures with stage I filling show strong fluorescence reaction under the microscope, demonstrating filled fractures can still be effective due to internal microfractures. The formation and development of fractures in carbonate reservoirs are controlled by four factors: tectonic stress field, fault, lithology and karstification. The magnitude and direction of the tectonic stress field during the fracture formation period determine the fracture size and distribution mode. Under the significant influence of strike-slip faults a large number of fault-associated fractures are developed, and their fracturing pattern is consistent with that of strike-slip faults. The radius of influence of a single strike-slip fault zone is 2048.56 m, and the development of fault controlled fractures is strong within 0-308.25 m from the fault zone and significantly reduced beyond this range. The tension-shear section of the strike-slip fault and the end of the fault zone show good fracture development, and the active plate has high fracture density with more abundant oil/gas filled fractures. The level of fracture development is positively correlated with the content of brittle minerals and significantly influenced by Young’s modulus and Poisson’s ratio. The highest level of fracture development is found in dolomite, and the most effective fractures are in sandy limestone. Large-scale fracture development are seen on mounds under karst platform in shallow areas and along the vertical direction, with an average fracture density of 2.67 m^-1, strongly enhancing reservoir performance.

Key words: development characteristics, controlling factors, carbonate reservoirs, Ordovician, Tahe oilfield

CLC Number:

HAN Pengyuan, DING Wenlong, YANG Debin, DENG Guangxiao, WANG Zhen, MA Hailong, LÜ Jing, GENG Tian. Characteristics and main controlling factors of fracture development in the Ordovician carbonate reservoir, Tahe oilfield[J]. Earth Science Frontiers, 2024, 31(5): 209-226.

Figures/Tables 16

Fig. 1 The study area. (a) Structural units of the Tarim Basin (modified after [36]). (b) Geographical location of the Tarim Basin.(c) Structural units of Tabei uplift and location of Tahe oilfield (modified after [42-43]).(d) Comprehensive lithological column and sedimentary-tectonic evolution characteristics of the Middle Cambrian-Lower Silurian in Tahe oilfield (modified after[25]).

Fig.2 Core specimens showing the characteristics of fracture development in Ordovician carbonate reservoir, Tahe oilfield

Fig.3 Characteristics of microfractures

Fig.4 Fracture orientation (a), dip direction (b) and dip angle (c) distributions from image logs

Fig.5 Pie charts of fracture dip angles (a), lengths (b), aperture (c) and filling levels (d)

Fig.6 Fracture density bar graph for wells under different fault conditions

Fig.7 Relationship between fracture dip angle and fracture aperture

Fig.8 Positive relationship between calculated comprehensive fracture index and observed fracture density

Fig.9 Fracture orientation distributions along fault zones

Fig.10 Relationship between fracture density and distance from fault zones

Fig.11 Relationship between segmentation of strike-slip faults and fracture density

Fig.12 Differences in fracture density distributions between active and passive plates in strike-slip faults

Fig.13 Influence of lithology on fracture development

Table 1 Comparison of rock mechanical parameters between different lithologies

井位	岩性	杨氏模量/GPa	泊松比	数据来源
X7	角砾灰岩	41.96	0.214	自测
X5	泥晶灰岩	64.94	0.390	自测
X5	亮晶灰岩	44.43	0.247	郑晓志^[91]
S13	砂屑灰岩	74.24	0.339
S13	泥灰岩	31.02	0.22
X10	泥晶灰岩	65.17	0.299
X4	泥晶灰岩	51.59	0.243
X8	泥微晶灰岩	37.67	0.307
X16	泥晶灰岩	62.7	0.297

Table 2 Statistics on fracture status of karst landforms

研究对象	裂缝线密度分区/ (条·m^-1)		岩溶地貌
			岩溶台地						岩溶陡坡		岩溶盆地
			峰丛洼地		丘从垄脊沟谷		丘从洼地		岩溶陡坡		岩溶盆地
			面积/ km²	占比/ %	面积/ km²	占比/ %	面积/ km²	占比/ %	面积/ km²	占比/ %	面积/ km²	占比/ %
奥陶系顶界面	I	3.5~>2.5	15.51	40.1	2.94	11.2	17.38	19.9	16.33	6.7	3.84	5.2
	II	2.5~>1.5	19.07	49.3	6.94	26.4	21.73	24.8	54.27	22.4	4.03	5.4
	III	1.5~>1.0	4.10	10.6	1.99	7.6	12.70	14.5	36.42	15.0	5.13	6.9
	IV	1.0~>0.5			13.36	50.9	35.54	40.6	76.75	31.7	52.42	70.6
	V	0.5~0.0			1.03	3.9	0.18	0.2	58.30	24.1	8.81	11.9
中下奥陶统地层	I	3.5~>2.5							1.44	0.5	0.43	0.5
	II	2.5~>1.5	5.86	14.1	0.34	1.6	9.97	14.1	22.73	8.7	2.15	2.7
	III	1.5~>1.0	9.79	23.6	5.08	23.1	14.15	20.0	72.21	27.6	24.24	30.6
	IV	1.0~>0.5	25.91	62.3	1.42	6.4	45.63	64.6	148.87	56.8	52.38	66.1
	V	0.5~0.0			15.15	68.9	0.92	1.3	16.64	6.4

Fig.14 Influence of karst landform on fracture development

References 94

[1]	韩长城, 林承焰, 鲁新便, 等. 塔河油田奥陶系碳酸盐岩岩溶斜坡断控岩溶储层特征及形成机制[J]. 石油与天然气地质, 2016, 37(5): 644-652.
[2]	金之钧, 蔡立国. 中国海相油气勘探前景、主要问题与对策[J]. 石油与天然气地质, 2006, 27(6): 722-730.
[3]	漆立新. 塔里木盆地下古生界碳酸盐岩大油气田勘探实践与展望[J]. 石油与天然气地质, 2014, 35(6): 771-779.
[4]	马永生, 何登发, 蔡勋育, 等. 中国海相碳酸盐岩的分布及油气地质基础问题[J]. 岩石学报, 2017, 33(4): 1007-1020.
[5]	鲁新便, 蔡忠贤. 缝洞型碳酸盐岩油藏古溶洞系统与油气开发: 以塔河碳酸盐岩溶洞型油藏为例[J]. 石油与天然气地质, 2010, 31(1): 22-27.
[6]	赵文智, 沈安江, 潘文庆, 等. 碳酸盐岩岩溶储层类型研究及对勘探的指导意义: 以塔里木盆地岩溶储层为例[J]. 岩石学报, 2013, 29(9): 3213-3222.
[7]	吕艳萍, 姜应兵, 高济元, 等. 塔河西部奥陶系古岩溶小流域的划分及其地质意义[J]. 断块油气田, 2021, 28(4): 440-445.
[8]	张文彪, 张亚雄, 段太忠, 等. 塔里木盆地塔河油田托甫台区奥陶系碳酸盐岩断溶体系层次建模方法[J]. 石油与天然气地质, 2022, 43(1): 207-218.
[9]	何治亮, 赵向原, 张文彪, 等. 深层-超深层碳酸盐岩储层精细地质建模技术进展与攻关方向[J]. 石油与天然气地质, 2023, 44(1): 16-33.
[10]	张三, 金强, 孙建芳, 等. 塔河地区奥陶系岩溶斜坡峰丘高地的形成及油气地质意义[J]. 石油勘探与开发, 2021, 48(2): 303-313. DOI
[11]	金强, 张三, 孙建芳, 等. 塔河油田奥陶系碳酸盐岩岩溶相形成和演化[J]. 石油学报, 2020, 41(5): 513-525. DOI
[12]	张娟, 谢润成, 杨敏, 等. 塔河油田主体区下奥陶统小尺度缝洞体形成机制与分布预测[J]. 地学前缘, 2023, 30(4): 51-64. DOI
[13]	杨德彬, 杨敏, 李新华, 等. 塔河油田碳酸盐岩小缝洞型储层特征及成因演化[J]. 油气地质与采收率, 2021, 28(1): 41-46.
[14]	吕心瑞, 李红凯, 魏荷花, 等. 碳酸盐岩储层多尺度缝洞体分类表征: 以塔河油田S80单元奥陶系油藏为例[J]. 石油与天然气地质, 2017, 38(4): 813-821.
[15]	邓光校, 马永强, 谢玮. 碳酸盐岩小缝洞群储集体地震表征方法[J]. 科学技术与工程, 2022(8): 3038-3042.
[16]	肖阳, 刘国平, 韩春元, 等. 冀中坳陷深层碳酸盐岩储层天然裂缝发育特征与主控因素[J]. 天然气工业, 2018, 38(11): 33-42.
[17]	艾合买提江·阿不都热和曼, 钟建华, 李阳, 等. 碳酸盐岩裂缝与岩溶作用研究[J]. 地质论评, 2008, 54(4): 485-493, 578.
[18]	AGUILERA R. Determination of subsurface distance between vertical parallel natural fractures based on core data: geologic NOTE[J]. AAPG Bulletin, 1988, 72(7): 845-51.
[19]	NELSON R. Geologic analysis of naturally fractured reservoirs: contributions in petroleum geology and engineering[M]. Houston: Gulf Publishing Company, 1985: 320.
[20]	赫俊民, 王小垚, 孙建芳, 等. 塔里木盆地塔河地区中—下奥陶统碳酸盐岩储层天然裂缝发育特征及主控因素[J]. 石油与天然气地质, 2019, 40(5): 1022-1030.
[21]	曾联波, 巩磊, 祖克威, 等. 柴达木盆地西部古近系储层裂缝有效性的影响因素[J]. 地质学报, 2012, 86(11): 1809-1814.
[22]	久凯, 丁文龙, 李玉喜, 等. 黔北地区构造特征与下寒武统页岩气储层裂缝研究[J]. 天然气地球科学, 2012, 23(4): 797-803. DOI
[23]	刘亿. 巴楚隆起鹰山组碳酸盐岩储层特征及其主控因素[D]. 成都: 成都理工大学, 2013.
[24]	王培俊. 塔河油田二区奥陶系裂缝特征及成因分析[D]. 青岛: 中国石油大学(华东), 2010.
[25]	史今雄. 塔河油田断裂对奥陶系碳酸盐岩缝洞储集体控制作用研究[D]. 北京: 中国石油大学(北京), 2020.
[26]	王震, 邓光校, 文欢, 等. 塔河油田碳酸盐岩叠前裂缝预测技术应用分析[J]. 工程地球物理学报, 2018, 15(1): 65-72.
[27]	蓝茜茜, 张逸伦, 康志宏. 基于样本优化的神经网络方法在储层裂缝识别中的应用[J]. 科学技术与工程, 2020, 20(21): 8530-8536.
[28]	康志江, 张冬梅, 张振坤, 等. 深层缝洞型油藏井间连通路径智能预测技术[J]. 石油与天然气地质, 2023, 44(5): 1290-1299.
[29]	刘学利, 翟晓先, 杨坚, 等. 塔河油田缝-洞型碳酸盐岩油藏等效数值模拟[J]. 新疆石油地质, 2006, 27(1): 76-78.
[30]	贾承造, 魏国齐, 姚慧君, 等. 盆地构造演化与区域构造地质[M]. 北京: 石油工业出版社, 1995.
[31]	何登发, 李德生. 塔里木盆地构造演化与油气聚集[M]. 北京: 地质出版社, 1996.
[32]	康玉柱, 康志宏. 塔里木盆地构造演化与油气[J]. 地球学报, 1994, 15(增刊2): Z2.
[33]	何碧竹, 焦存礼, 刘若涵, 等. 塔里木盆地新元古代构造古地理及深层有利烃源岩发育区预测[J]. 地学前缘, 2023, 30(4): 19-42. DOI
[34]	何登发. 中国多旋回叠合沉积盆地的形成演化、地质结构与油气分布规律[J]. 地学前缘, 2022, 29(6): 24-59. DOI
[35]	马庆佑, 吕海涛, 蒋华山, 等. 塔里木盆地台盆区构造单元划分方案[J]. 海相油气地质, 2015, 20(1): 1-9.
[36]	YU J B, LI Z, YANG L. Fault system impact on paleokarst distribution in the Ordovician Yingshan Formation in the central Tarim Basin, Northwest China[J]. Marine and Petroleum Geology, 2016, 71: 105-118.
[37]	焦方正, 翟晓先. 海相碳酸盐岩非常规大油气田: 塔河油田勘探研究与实践[M]. 北京: 石油工业出版社, 2008.
[38]	安海亭, 李海银, 王建忠, 等. 塔北地区构造和演化特征及其对油气成藏的控制[J]. 大地构造与成矿学, 2009, 33(1): 142-147.
[39]	何登发, 周新源, 杨海军, 等. 塔里木盆地克拉通内古隆起的成因机制与构造类型[J]. 地学前缘, 2008, 15(2): 207-221.
[40]	贾承造. 中国塔里木盆地构造特征与油气[M]. 北京: 石油工业出版社, 1997.
[41]	汤良杰. 塔里木盆地演化和构造样式[M]. 北京: 地质出版社, 1996.
[42]	黄少英, 宋兴国, 罗彩明, 等. 塔北隆起X型走滑断裂成因机制的新解释[J]. 现代地质, 2021, 35(6): 1797-1808, 1829.
[43]	HAN P, DIAO X D, DING W, et al. Spatial distribution prediction of pre-Sinian volcanic and metamorphic rocks in Xinhenan-Sandaoqiao Area, Northern Tarim Basin[J]. Interpretation, 2022, 10(2): T237-T251.
[44]	翟晓先. 塔里木盆地塔河特大型油气田勘探实践与认识[J]. 石油实验地质, 2011, 33(4): 323-331.
[45]	丁文龙, 漆立新, 吕海涛, 等. 利用FMI资料分析塔河油田南部中—下奥陶统储层构造应力场[J]. 现代地质, 2009, 23(5): 852-859.
[46]	漆立新, 云露. 塔河油田奥陶系碳酸盐岩岩溶发育特征与主控因素[J]. 石油与天然气地质, 2010, 31(1): 1-12.
[47]	张三, 金强, 乔贞, 等. 塔河油田奥陶系构造差异演化及油气地质意义[J]. 中国矿业大学学报, 2020, 49(3): 576-586.
[48]	张小兵, 吕海涛, 赵锡奎, 等. 塔河油田中下奥陶统顶面古构造演化及油气关系[J]. 石油实验地质, 2011, 33(3): 233-238.
[49]	何治亮, 彭守涛, 张涛. 塔里木盆地塔河地区奥陶系储层形成的控制因素与复合-联合成因机制[J]. 石油与天然气地质, 2010, 31(6): 743-752.
[50]	马庆佑, 曾联波, 徐旭辉, 等. 塔河油田奥陶系走滑断裂体系特征及成因机制[J]. 地质学报, 2023, 97(2): 496-506.
[51]	陈红汉, 吴悠, 丰勇, 等. 塔河油田奥陶系油气成藏期次及年代学[J]. 石油与天然气地质, 2014, 35(6): 806-819.
[52]	丁烽娟. 塔河油田六区奥陶系碳酸盐岩裂缝网络模型研究[D]. 青岛: 中国石油大学(华东), 2016.
[53]	施伟军, 席斌斌, 秦建中, 等. 单体油气包裹体激光剥蚀在线成分分析技术: 以塔河油田奥陶系储层为例[J]. 石油学报, 2016, 37(2): 196-206. DOI
[54]	陈轩, 刘王涵, 鲍典, 等. 塔河油田奥陶系古岩溶洞穴充填物时代鉴别特征及其储集意义[J]. 地学前缘, 2023, 30(4): 65-75. DOI
[55]	韩长城, 林承焰, 任丽华, 等. 塔里木盆地塔河10区奥陶系断裂特征及对岩溶储层的控制作用[J]. 天然气地球科学, 2016, 27(5): 790-798. DOI
[56]	汪洋, 张哨楠, 刘永立. 塔里木盆地塔河油田走滑断裂活动对油气成藏的控制作用: 以托甫39断裂带为例[J]. 石油实验地质, 2022, 44(3): 394-401.
[57]	张涛. 塔里木盆地阿克库勒凸起奥陶系岩溶型储层形成与保持研究[D]. 北京: 中国地质大学(北京), 2012.
[58]	周文, 李秀华, 金文辉, 等. 塔河奥陶系油藏断裂对古岩溶的控制作用[J]. 岩石学报, 2011, 27(8): 2339-2348.
[59]	边瑞康, 张金川, 唐玄, 等. 塔河油田深层能量场特征及其与油气运聚关系[J]. 石油勘探与开发, 2010, 37(4): 416-423.
[60]	赵向原, 胡向阳, 肖开华, 等. 川西彭州地区雷口坡组碳酸盐岩储层裂缝特征及主控因素[J]. 石油与天然气地质, 2018, 39(1): 30-39, 152.
[61]	ANDERS M H, LAUBACH S E, SCHOLZ C H. Microfractures: a review[J]. Journal of Structural Geology, 2014, 69: 377-394.
[62]	PERMADI P, MARHAENDRAJANA T, NANDYA S, 等. 碳酸盐岩储集层微裂缝的识别与表征[J]. 石油勘探与开发, 2022, 49(2): 366-376. DOI
[63]	ZHAO X, SUN M D, UKAOMAH C F, et al. Pore connectivity and microfracture characteristics of Longmaxi shale in the Fuling gas field: insights from mercury intrusion capillary pressure analysis[J]. Gas Science and Engineering, 2023, 119: 205134.
[64]	王濡岳, 丁文龙, 龚大建, 等. 渝东南—黔北地区下寒武统牛蹄塘组页岩裂缝发育特征与主控因素[J]. 石油学报, 2016, 37(7): 832-845, 877. DOI
[65]	张启燕, 刘晓, 史维鑫, 等. 基于微米CT和扫描电镜的碳酸盐岩微观结构特征分析[J]. 科学技术与工程, 2022, 22(34): 15043-15051.
[66]	盛军, 阳成, 徐立, 等. 数字岩心技术在致密储层微观渗流特征研究中的应用[J]. 西安石油大学学报(自然科学版), 2018, 33(5): 83-89.
[67]	张奎华, 孙中良, 张关龙, 等. 准噶尔盆地哈山地区下二叠统风城组泥页岩优势岩相与页岩油富集模式[J]. 石油实验地质, 2023, 45(4): 593-605.
[68]	张满郎, 郭振华, 张林, 等. 四川安岳气田龙王庙组颗粒滩岩溶储层发育特征及主控因素[J]. 地学前缘, 2021, 28(1): 235-248. DOI
[69]	刘敬寿, 丁文龙, 肖子亢, 等. 储层裂缝综合表征与预测研究进展[J]. 地球物理学进展, 2019, 34(6): 2283-2300.
[70]	曾联波, 李忠兴, 史成恩, 等. 鄂尔多斯盆地上三叠统延长组特低渗透砂岩储层裂缝特征及成因[J]. 地质学报, 2007, 81(2): 174-180.
[71]	李理, 桑晓彤, 陈霞飞. 低渗透储层裂缝研究现状及进展[J]. 地球物理学进展, 2017, 32(6): 2472-2484.
[72]	赵向原, 胡向阳, 曾联波, 等. 四川盆地元坝地区长兴组礁滩相储层天然裂缝有效性评价[J]. 天然气工业, 2017, 37(2): 52-61.
[73]	LAUBACH S E, WARD M E. Diagenesis in porosity evolution of opening-mode fractures, Middle Triassic to Lower Jurassic La Boca Formation, NE Mexico[J]. Tectonophysics, 2006, 419(1): 75-97.
[74]	李树博, 姜伟, 张效恭, 等. 塔里木盆地巴楚凸起H气田奥陶系裂缝主控因素及演化序列研究[J]. 地质力学学报, 2019, 25(4): 518-526.
[75]	鞠玮, 牛小兵, 冯胜斌, 等. 页岩油储层现今地应力场与裂缝有效性评价: 以鄂尔多斯盆地延长组长7油层组为例[J]. 中国矿业大学学报, 2020, 49(5): 931-940.
[76]	FINKBEINER T, BARTON C A, ZOBACK M D. Relationships among In-situ stress, fractures and faults, and fluid flow: Monterey Formation, santa maria basin, California[J]. AAPG Bulletin, 1997, 81(12): 1975-1999.
[77]	刘国平, 曾联波, 雷茂盛, 等. 徐家围子断陷火山岩储层裂缝发育特征及主控因素[J]. 中国地质, 2016, 43(1): 329-337.
[78]	LIU J S, DING W L, YANG H M, et al. Quantitative multiparameter prediction of fractured tight sandstone reservoirs: a case study of the Yanchang Formation of the Ordos Basin, central China[J]. SPE Journal, 2021, 26(5): 3342-3373.
[79]	LIU J S, DING W L, YANG H M, et al. Quantitative prediction of fractures using the finite element method: a case study of the lower Silurian Longmaxi Formation in northern Guizhou, South China[J]. Journal of Asian Earth Sciences, 2018, 154: 397-418.
[80]	LIU J S, DING W L, DAI J S, et al. Quantitative prediction of lower order faults based on the finite element method: a case study of the M35 fault block in the western Hanliu fault zone in the Gaoyou Sag, East China[J]. Tectonics, 2018, 37(10): 3479-3499.
[81]	LYAKHOVSKY V, BEN-ZION Y, AGNON A. Distributed damage, faulting, and friction[J]. Journal of Geophysical Research: Solid Earth, 1997, 102(B12): 27635-27649.
[82]	周铂文, 陈红汉, 云露, 等. 塔里木盆地顺北地区下古生界走滑断裂带断距分段差异与断层宽度关系[J]. 地球科学, 2022(2): 437-451.
[83]	邓尚, 李慧莉, 韩俊, 等. 塔里木盆地顺北5号走滑断裂中段活动特征及其地质意义[J]. 石油与天然气地质, 2019, 40(5): 990-998, 1073.
[84]	张子隆, 杨威, 王千军, 等. 走滑断裂不同结构单元输导、运聚特性及其差异控藏模式: 以准噶尔盆地乌尔禾沥青矿地区为例[J]. 断块油气田, 2023, 30(3): 424-433.
[85]	黄诚, 云露, 曹自成, 等. 塔里木盆地顺北地区中—下奥陶统“断控” 缝洞系统划分与形成机制[J]. 石油与天然气地质, 2022, 43(1): 54-68.
[86]	李兵, 邓尚, 李王鹏, 等. 塔里木盆地塔河地区走滑断裂体系活动特征与油气地质意义[J]. 特种油气藏, 2019, 26(4): 45-51.
[87]	NELSON R A, MOLDOVANYI E P, MATCEK C C, et al. Production characteristics of the fractured reservoirs of the La Paz field, Maracaibo Basin, Venezuela[J]. AAPG Bulletin, 2000, 84(11): 1791-1809.
[88]	PIREH A, ALAVI S A, GHASSEMI M R, et al. Analysis of natural fractures and effect of deformation intensity on fracture density in Garau Formation for shale gas development within two anticlines of Zagros fold and thrust belt, Iran[J]. Journal of Petroleum Science and Engineering, 2015, 125: 162-180.
[89]	李长海, 赵伦, 刘波, 等. 碳酸盐岩裂缝研究进展及发展趋势[J]. 地质科技通报, 2021, 40(4): 31-48.
[90]	KORNEVA I, BASTESEN E, CORLETT H, et al. The effects of dolomitization on petrophysical properties and fracture distribution within rift-related carbonates (Hammam Faraun Fault Block, Suez Rift, Egypt)[J]. Journal of Structural Geology, 2018, 108: 108-120.
[91]	郑晓志. 塔河油田碳酸盐岩储层应力分布及在酸压中的应用[D]. 北京: 中国石油大学(北京), 2007.
[92]	岳喜伟, 戴俊生, 王珂. 岩石力学参数对裂缝发育程度的影响[J]. 地质力学学报, 2014, 20(4): 372-378.
[93]	孙帅, 侯贵廷. 岩石力学参数影响断背斜内张裂缝发育带的概念模型[J]. 石油与天然气地质, 2020, 41(3): 455-462.
[94]	LOUCKS R G. Paleocave carbonate reservoirs: origins, burial-depth modifications, spatial complexity, and reservoir implications[J]. AAPG Bulletin, 1999, 83(11): 1795-1834.