Structural Deformation and Shale Gas Preservation Conditions in the Changning Area of the Southern Sichuan Basin

doi:10.19657/j.geoscience.1000-8527.2024.061

Abstract

Abstract:

The Changning area is located in the southern Sichuan Basin. The shale in the Upper Ordovician Wufeng Formation and the Lower Silurian Longmaxi Formation is of high quality and exhibits favorable source-reservoir-cap conditions. During the Phanerozoic, multi-stage extension, extrusion and strike-slip deformation, along with strong uplift and denudation, resulted in very complex preservation conditions for shale gas. Based on the structural characteristics and tectonic evolution in this area, this paper examines how various structural factors influence the preservation conditions of shale gas. This study also proposes a comprehensive quantitative evaluation method for assessing shale gas preservation conditions and predicts potential exploration areas. The study results show that the Changning area mainly features two groups of structures: NE-trending and NW-trending. Both sets of structures are related to folds developed on the hanging wall of basement-involved fault. They formed during the Early and Late Yanshanian periods, respectively, and some NE-trending structures were modified by strike-slip events during the Himalayan period. The main structural factors affecting shale gas preservation conditions include the timing of tectonic transformation, uplift and denudation, stratigraphic dip, multi-scale fault-fracture systems, and the current in-situ stress direction. Based on the impact of various structural elements on the shale gas preservation, a quantitative evaluation method for assessing preservation conditions in the Changning area is proposed. The evaluation results indicate that the shale gas preservation conditions in the Jianwu syncline are the most promising, followed by the Tiangongtang anticline, Shuanglong syncline, and Luochang syncline.

Key words: Changning, structural deformation, structural evolution, Wufeng Formation-Longmaxi Formation, shale gas preservation condition

CLC Number:

YANG Shaohang, LUO Liang, MA Shijie, XUE Meng, ZENG Lianbo, NIE Zhou, YOU Yuling, ZHOU Yangfan. Structural Deformation and Shale Gas Preservation Conditions in the Changning Area of the Southern Sichuan Basin[J]. Geoscience, 2024, 38(06): 1458-1472.

Figures/Tables 15

Fig.1 Structural map of the bottom of the Wufeng Formation in Changning

Fig.2 Interpretation of typical seismic sections across the NW-direction structures in Changning (seeing Fig.1 for the location of sections)

Fig.3 Interpretation of typical seismic sections across the NE-direction structures in Changning (seeing Fig.1 for the location of section)

Fig.4 Balanced cross-section through the Tiangongtang anticline in Changning(same section as Fig.2(a)

Fig.5 Balanced cross-section through the Shuanglong and Luochang synclines in Changning ( same section as Fig.3)

Fig.6 Relationships between fracture permeability and erosion in Changning

Fig.7 Photos of field and core fractures in Changning

Fig.8 Relationships between different fault scales and production testing in Changning

Table 1 Statistics of production testing from selected wells in Changning and their distances from faults at various levels

井位	测试产量 (m³/t)	距一级断层(km)	距二级断层(km)	距三级断层(km)	距四级断层(km)
宁208	0.1	1.5	0.4	2.1	7.0
宁217	11.1	0.5	2.9	0.3	4.4
宁216	20.3	1.3	0.8	2.8	0.5
宁225	0.2	0.4	0.8	0.8	0.5
宁215	6.8	0.9	1.0	1.1	0.6
宁224	1.4	0.2	4.3	5.8	2.9
宁203	1.3	7.0	6.3	2.3	3.0
宁209	1.3	6.0	5.3	1.3	0.2
宜202	6.5	7.0	20.3	6.4	2.2
宁201	1.7	6.0	3.8	2.2	1.9
宁228	1.9	10.4	3.3	4.1	2.7
宁214	24.7	4.3	4.3	4.2	5.6
宁213	21.9	2.9	6.5	0.7	9.1
宁222	10.1	6.5	2.0	2.5	5.6
宁211	10.2	9.3	9.6	2.8	1.3

Table 2 Statistics of fracture density from typical wells in the Changning

构造单元	钻井	裂缝密度(条/m)
构造单元	钻井	穿层剪切裂缝	顺层剪切裂缝	层内张开裂缝	总密度
天宫堂背斜	宜202	0.19	0.59	2.28	3.05
天宫堂背斜	宁西202	7.00	2.00	1.69	10.69
双龙向斜	宁219	1.58	0.24	1.26	3.08
罗场向斜	宁218	1.05	0.53	0.81	2.39
罗场向斜	宁228	0.36	0.21	0.53	1.10
建武向斜	宁213	0.50	/	4.03	4.54
	宁216	0.92	0.04	0.63	1.60
	宁227	0.47	0.16	/	0.63

Fig.9 Distribution map of multi-scale fault and fracture systems in the Longmaxi Formation, including stratigraphic inclination and the current maximum principal stress direction in Changning

Table 3 Evaluation parameters for shale gas conservation conditions in the Longmaxi Formation, Changning

Fig.10 Analytical gas and test gas content for some wells in Changning, and the SP relationship between these values and the comprehensive evaluation index

Fig.11 Comprehensive evaluation zoning map of shale gas preservation conditions in Changning

Table 4 Evaluation index for shale gas preservation conditions across different structural units in the Longmaxi Formation, Changning

评价参数指标	构造改造时间	剥蚀量	构造样式	地层倾角	Ⅰ、Ⅱ 级断层密度	目的层底界埋深	距剥蚀线距离	距Ⅰ、Ⅱ 级断层的距离	裂缝密度		现金地应力与断层夹角	综合评价指数
评价参数指标	构造改造时间	剥蚀量	构造样式	地层倾角	Ⅰ、Ⅱ 级断层密度	目的层底界埋深	距剥蚀线距离	距Ⅰ、Ⅱ 级断层的距离	层内张裂缝密度	穿层剪切裂缝密度	现金地应力与断层夹角	综合评价指数
建武向斜	0.75	0.75	1	0.75	1	1	1	1	1	1	0.75	0.9
天宫堂背斜	0.75	0.50	1	0.75	1	0.75	1	0.75	1	1	1	0.85
罗场向斜	0.5	0.75	0.5	1	0.5	0.5	1	0.5	0.5	0.5	0.75	0.65
双龙向斜	0.5	0.75	0.5	1	0.75	0.5	1	0.5	0.75	0.5	0.75	0.6875

References 63

[1]	邹才能, 赵群, 董大忠, 等. 页岩气基本特征、主要挑战与未来前景[J]. 天然气地球科学, 2017, 28(12): 1781-1796. DOI
[2]	董大忠, 王玉满, 李新景, 等. 中国页岩气勘探开发新突破及发展前景思考[J]. 天然气工业, 2016, 36(1): 19-32.
[3]	马新华, 谢军. 川南地区页岩气勘探开发进展及发展前景[J]. 石油勘探与开发, 2018, 45(1): 161-169. DOI
[4]	王玉满, 董大忠, 李建忠, 等. 川南下志留统龙马溪组页岩气储层特征[J]. 石油学报, 2012, 33(4): 551-561. DOI
[5]	李东升, 高平, 盖海峰, 等. 川东南地区龙马溪组页岩有机质纳米孔隙结构表征[J]. 现代地质, 2023, 37(5): 1293-1305.
[6]	张国伟, 郭安林, 王岳军, 等. 中国华南大陆构造与问题[J]. 中国科学(地球科学), 2013, 43(10): 1553-1582.
[7]	徐政语, 姚根顺, 梁兴, 等. 扬子陆块下古生界页岩气保存条件分析[J]. 石油实验地质, 2015, 37(4): 407-417.
[8]	刘树根, 王一刚, 孙玮, 等. 拉张槽对四川盆地海相油气分布的控制作用[J]. 成都理工大学学报(自然科学版), 2016, 43(1): 1-23.
[9]	DAI J X, ZOU C N, LIAO S M, et al. Geochemistry of the extremely high thermal maturity Longmaxi shale gas, southern Sichuan Basin[J]. Organic Geochemistry, 2014, 74: 3-12.
[10]	HOU Y G, ZHANG K P, WANG F R, et al. Structural evolution of organic matter and implications for graphitization in over-mature marine shales, South China[J]. Marine and Petroleum Geology, 2019, 109: 304-316.
[11]	邹才能, 董大忠, 王玉满, 等. 中国页岩气特征、挑战及前景(一)[J]. 石油勘探与开发, 2015, 42(6): 689-701.
[12]	楼章华, 张欣柯, 吴宇辰, 等. 四川盆地南川地区及邻区页岩气保存差异的流体响应特征[J]. 油气藏评价与开发, 2023, 13(4):451-458.
[13]	马永生, 蔡勋育, 赵培荣. 中国页岩气勘探开发理论认识与实践[J]. 石油勘探与开发, 2018, 45(4): 561-574. DOI
[14]	何登发, 鲁人齐, 黄涵宇, 等. 长宁页岩气开发区地震的构造地质背景[J]. 石油勘探与开发, 2019, 46(5): 993-1006. DOI
[15]	韩倩. 川南长宁背斜构造几何学特征及形成演化[D]. 成都: 成都理工大学, 2020.
[16]	姚金鹏, 陈伟. 川南长宁背斜形成的几何运动学分析[J]. 化工设计通讯, 2021, 47(3): 191-192.
[17]	张岳桥, 董树文, 李建华, 等. 中生代多向挤压构造作用与四川盆地的形成和改造[J]. 中国地质, 2011, 38(2): 233-250.
[18]	邓宾, 刘树根, 刘顺, 等. 四川盆地地表剥蚀量恢复及其意义[J]. 成都理工大学学报(自然科学版), 2009, 36(6): 675-686.
[19]	RICHARDSON N J, DENSMORE A L, SEWARD D, et al. Extraordinary denudation in the Sichuan Basin: Insights from low-temperature thermochronology adjacent to the eastern margin of the Tibetan Plateau[J]. Journal of Geophysical Research (Solid Earth), 2008, 113(4): B04409.
[20]	TIAN Y T, KOHN B, QIU N, et al. Eocene to Miocene out-of-sequence deformation in the eastern Tibetan Plateau: Insights from shortening structures in the Sichuan Basin[J]. Journal of Geophysical Research(Solid Earth), 2018, 123: 1840-1855.
[21]	罗志立, 龙学明. 龙门山造山带崛起和川西陆前盆地沉降[J]. 四川地质学报, 1992, 12(1): 1-17.
[22]	陈尚斌, 朱炎铭, 王红岩, 等. 四川盆地南缘下志留统龙马溪组页岩气储层矿物成分特征及意义[J]. 石油学报, 2011, 32(5): 775-782. DOI
[23]	邓宾. 四川盆地中—新生代盆-山结构与油气分布[D]. 成都: 成都理工大学, 2013.
[24]	胡召齐, 朱光, 刘国生, 等. 川东“侏罗山式” 褶皱带形成时代: 不整合面的证据[J]. 地质论评, 2009, 55(1): 32-42.
[25]	SHEN C B, MEI L F, XU S H. Fission track dating of Mesozoic sandstones and its tectonic significance in the Eastern Sichuan Basin, China[J]. Radiation Measurements, 2009, 44(9/10): 945-949.
[26]	梅廉夫, 刘昭茜, 汤济广, 等. 湘鄂西—川东中生代陆内递进扩展变形: 来自裂变径迹和平衡剖面的证据[J]. 地球科学, 2010, 35(2): 161-174.
[27]	SHI H C, SHI X B, GLASMACHER U A, et al. The evolution of eastern Sichuan Basin, Yangtze Block since Cretaceous: Constraints from low temperature thermochronology[J]. Journal of Asian Earth Sciences, 2016, 116: 208-221.
[28]	张岳桥, 赵越, 董树文, 等. 中国东部及邻区早白垩世裂陷盆地构造演化阶段[J]. 地学前缘, 2004, 11(3): 123-133.
[29]	唐永, 周立夫, 陈孔全, 等. 川东南构造应力场地质分析及构造变形成因机制讨论[J]. 地质论评, 2018, 64(1): 15-28.
[30]	张经国, 陈伟, 孟立丰. 长宁页岩气田建武向斜构造解析及成因机制[J]. 化工设计通讯, 2021, 47(3): 193-194.
[31]	王二七, 尹纪云. 川西南新生代构造作用以及四川原型盆地的破坏[J]. 西北大学学报(自然科学版), 2009, 39(3): 359-367.
[32]	WILSON C J L, FOWLER A P. Denudational response to surface uplift in East Tibet: Evidence from apatite fission-track thermochronology[J]. Geological Society of America Bulletin, 2011, 123(9/10): 1966-1987.
[33]	WANG E, MENG K, SU Z, et al. Block rotation: Tectonic response of the Sichuan Basin to the southeastward growth of the Tibetan Plateau along the Xianshuihe-Xiaojiang fault[J]. Tecto-nics, 2014, 33(5): 686-718.
[34]	张梦琳, 李郭琴, 何嘉, 等. 川西南缘天宫堂构造奥陶系五峰组—志留系龙马溪组页岩气富集主控因素[J]. 岩性油气藏, 2022, 34(2): 141-151.
[35]	刘树根, 孙玮, 钟勇, 等. 四川海相克拉通盆地显生宙演化阶段及其特征[J]. 岩石学报, 2017, 33(4): 1058-1072.
[36]	汤济广, 汪凯明, 秦德超, 等. 川东南南川地区构造变形与页岩气富集[J]. 地质科技通报, 2021, 40(5): 11-21.
[37]	覃作鹏, 刘树根, 邓宾, 等. 川东南构造带中新生代多期构造特征及演化[J]. 成都理工大学学报(自然科学版), 2013, 40(6): 703-711.
[38]	王学军, 杨志如, 韩冰. 四川盆地叠合演化与油气聚集[J]. 地学前缘, 2015, 22(3): 161-173. DOI
[39]	聂海宽, 包书景, 高波, 等. 四川盆地及其周缘下古生界页岩气保存条件研究[J]. 地学前缘, 2012, 19(3): 280-294.
[40]	胡东风, 张汉荣, 倪楷, 等. 四川盆地东南缘海相页岩气保存条件及其主控因素[J]. 天然气工业, 2014, 34(6): 17-23.
[41]	汤济广, 李豫, 汪凯明, 等. 四川盆地东南地区龙马溪组页岩气有效保存区综合评价[J]. 天然气工业, 2015, 35(5): 15-23.
[42]	王濡岳, 丁文龙, 龚大建, 等. 黔北地区海相页岩气保存条件: 以贵州岑巩区块下寒武统牛蹄塘组为例[J]. 石油与天然气地质, 2016, 37(1): 45-55.
[43]	谌志远. 南方海相页岩气散失控制因素研究: 以四川盆地南缘为例[D]. 北京: 中国石油大学(北京), 2019.
[44]	何顺, 秦启荣, 范存辉, 等. 川东南丁山地区五峰—龙马溪组页岩储层特征及影响因素[J]. 油气藏评价与开发, 2019, 9(4): 61-67, 78.
[45]	李轲, 陈杨, 牟必鑫, 等. 西昌盆地南部地区志留系龙马溪组页岩气保存条件的评价[J]. 非常规油气, 2021, 8(1): 34-42.
[46]	张海涛, 张颖, 何希鹏, 等. 渝东南武隆地区构造作用对页岩气形成与保存的影响[J]. 中国石油勘探, 2018, 23(5): 47-56. DOI
[47]	龙小军. 焦石坝地区构造变形差异及保存条件解析[J]. 非常规油气, 2018, 5(5): 28-34.
[48]	曾联波, 肖淑蓉. 低渗透储集层中的泥岩裂缝储集体[J]. 石油实验地质, 1999, 21(3): 266-269.
[49]	姜磊. 强改造作用下川南下古生界页岩气保存条件研究[D]. 成都: 成都理工大学, 2019.
[50]	周政. 长宁地区五峰组—龙马溪组页岩气富集特征研究[D]. 成都: 成都理工大学, 2020.
[51]	LIU S G, YANG Y, DENG B, et al. Tectonic evolution of the Sichuan Basin, Southwest China[J]. Earth-Science Reviews, 2021, 213: 103470.
[52]	于俊友, 雍自权, 程凌云, 等. 强改造区龙马溪组页岩气保存条件指数评价[J]. 长江大学学报(自科版), 2015, 12(35): 1-7, 9.
[53]	ZENG L B, LYU W Y, LI J, et al. Natural fractures and their influence on shale gas enrichment in Sichuan Basin, China[J]. Journal of Natural Gas Science and Engineering, 2016, 30: 1-9.
[54]	梁兴, 王高成, 徐政语, 等. 中国南方海相复杂山地页岩气储层甜点综合评价技术: 以昭通国家级页岩气示范区为例[J]. 天然气工业, 2016, 36(1): 33-42.
[55]	唐相路, 姜振学, 张莺莺, 等. 渝东南地区页岩气富集区差异性分布成因[J]. 西安石油大学学报(自然科学版), 2015, 30(3): 24-30, 35, 7.
[56]	张昆. 复杂构造背景海相页岩气保存机理与评价方法[D]. 北京: 中国石油大学(北京), 2019.
[57]	黄瑞广, 罗超, 公子龙, 等. 断裂系统与页岩气保存条件之间的关系: 以泸州地区为例[J]. 山东化工, 2022, 51(5): 148-153, 158.
[58]	蒋代琴, 李平平, 邹华耀. 川东北元坝地区侏罗系陆相页岩天然裂缝发育特征及其对页岩油气富集和保存的影响[J]. 现代地质, 2024, 38(2):362-372.
[59]	向杰, 陈尚斌, 王阳, 等. 断裂体系对页岩气保存的影响: 以滇东北地区五峰—龙马溪组为例[J]. 煤炭学报, 2021, 46(11): 3599-3612.
[60]	田鹤, 曾联波, 徐翔, 等. 四川盆地涪陵地区海相页岩天然裂缝特征及对页岩气的影响[J]. 石油与天然气地质, 2020, 41(3): 474-483.
[61]	俞雨溪, 王宗秀, 冯兴强, 等. 剪切作用对页岩有机质孔发育特征和吸附能力的影响[J]. 地质力学学报, 2020, 26(6): 830-839.
[62]	陈永峤, 周新桂, 于兴河, 等. 断层封闭性要素与封闭效应[J]. 石油勘探与开发, 2003, 30(6): 38-40.
[63]	陆应新, 胡望水, 汤济广, 等. 川东南丁山构造龙马溪组页岩裂缝发育与分布[J]. 长江大学学报(自科版), 2016, 13(8): 6-10, 2.