The Tianfu Gas Field in the Sichuan Basin is a core block for the large-scale, economic development of Jurassic tight gas in China. The first sub-member of the first member of the Shaximiao Formation in the Zhongjiang Block hosts typical low-porosity and low-permeability tight sandstone reservoirs. Based on detailed field geological surveys and core observations, this study employed multiple technical methods, including cast thin sections, scanning electron microscopy, computed tomography (CT) scanning, and nuclear magnetic resonance (NMR) to investigate sedimentary microfacies' characteristics, analyze key reservoir properties (e.g., reservoir space types and pore structure), and clarify the main controlling factors of reservoir development. The results indicate the following: (1) The sedimentary period of the first sub-member of the first member of the Shaximiao formation (Es11) was controlled by a subtropical humid climate, with widespread gray mudstones and bedding-parallel plant fossil fragments. The main sedimentary environment was a shallow-water delta front, where the underwater distributary channel microfacies was the dominant facies belt. (2) Reservoir lithology is dominated by lithic arkose and feldspathic litharenite, with low compositional and structural maturity. Residual primary intergranular pores are the dominant reservoir space type, followed by intragranular dissolved pores in feldspar and lithic fragments. (3) The pore structure is characterized by a small pore-throat radius, poor sorting, and strong heterogeneity. Reservoirs can be subdivided into three categories, with Types II and III being the main types developed in this block. (4) Underwater distributary channels of the shallow-water delta are the main occurrence of reservoir sand bodies. During the burial diagenetic stage, calcite and laumontite cementation and filling led to reservoir densification. Meanwhile, early-formed chlorite rim cement effectively protected primary pores by inhibiting grain compaction and quartz overgrowth. Superimposed with the dissolution and alteration of feldspar, lithic fragments, and other components by late acidic fluids, effective pores were further expanded. The synergistic coupling of these sand-controlling factors and the "densification-protection-alteration" diagenetic process jointly constitutes the formation mechanism of high-quality reservoirs. This mechanism can provide a reliable theoretical basis for the accurate prediction of reservoir "sweet spots" and the optimal selection of horizontal well targets in the Zhongjiang Block of the Tianfu Gas Field.

The Jurassic Lianggaoshan Formation in eastern Sichuan Basin is a key target for shale oil exploration.It faces challenges in three-pressure prediction due to complex structural and sedimentary interactions,as well as strong reservoir anisotropy.These issues often lead to wellbore instability and gas logging anomalies during drilling.This study presents an integrated workflow that combines residual moveout correction using correlation-based dynamic time warping(CDTW),high-resolution seismic waveform indication inversion,and three-pressure prediction of jointing well-seismic data.Applied to the LT1 well block,the workflow effectively corrects anisotropic residual moveout in image gathers,leading to a signal strength increase of over 10％in frequency bands above 30 Hz and enhancing event continuity.High-resolution rock mechanical parameters are obtained through seismic waveform inversion and regional calibration,enabling the prediction of three-dimensional pore pressure,collapse pressure and fracture pressure.The results are consistent with actual drilling gas shows and core data,confirming the method's accuracy and supporting mud weight planning and wellbore stability efforts.This cost-effective and technically robust approach proves highly reliable in complex environments with significant heterogeneity and anisotropy,assisting drilling decisions and risk management in eastern Sichuan and similar challenging geological settings.

In the central Sichuan area, shallow continental clastic strata and deep marine carbonate formations are vertically developed. The mechanisms that generate abnormal pressure differ between these two types of strata, and the overall heterogeneity is strong. Conventional empirical pore-pressure prediction methods are markedly inadequate in deep carbonate rocks, exhibit poor universality, and fail to achieve accurate prediction over the entire well section. Therefore, using logging, geological and well-test data from the study area, this paper compares the Eaton, effective‑stress and Fillippone methods for pore-pressure prediction. The results indicate that both the Eaton and effective‑stress methods are based on the normal compaction trend line and yield relatively large prediction errors in deep carbonate formations, whereas the Fillippone method performs best. On this basis, the paper further modifies the Fillippone method by adjusting the velocity‑ratio relationship so that the velocity response in abnormally high‑pressure intervals changes from “attenuated feedback” to “compensatory uplift”. The research results demonstrate that the proposed method achieves higher prediction accuracy, and the predicted pressure coefficients agree well with fracture and electrical image data, making it more suitable for pore‑pressure prediction in deep carbonate formations and capable of effectively supporting rapid and efficient drilling operations.

The Changxing Formation in the central Sichuan Basin developed on a central isolated gentle-slope platform, where multiple rows of high-energy reef-shoal bodies occur. In some local areas, dolomitized reservoirs are well developed, indicating significant exploration potential. However, strong reservoir heterogeneity and the pronounced characteristic of “one reef, one reservoir” have resulted in challenges such as unclear delineation of internal reservoir boundaries and ambiguous seismic response characteristics. Therefore, further refined delineation of reef-shoal body boundaries are required. Based on geological and logging data, the petrological and seismic response characteristics of reef-shoal reservoirs in the Changxing Formation were first clarified. Combined with the results of forward modeling, a seismic identification model for reef-shoal reservoirs was then established. Subsequently, by integrating paleogeomorphic restoration, seismic attribute analysis, and related techniques, a method for delineating internal boundaries—namely, the Three-Determination Method—was proposed. Finally, through the combined application of seismic inversion, seismic facies analysis, and related techniques, the vertical and lateral distribution characteristics of reef-shoal reservoirs were defined. The results indicate that, vertically, reef-shoal reservoirs in the study area are mainly developed in the Chang 1 Member and the middle-upper part of the Chang 2 Member, with thicknesses ranging from 10 to 60 m. Laterally, they are primarily distributed along the platform margin and at local paleogeomorphic highs within the platform, and the characteristic of “one reef, one reservoir” is evident. Reef-shoal bodies in the platform-margin zone, characterized by clear seismic response patterns and relatively large individual extents, still exhibit considerable exploration potential.

This research aims to address the ambiguity surrounding the extent of development of Changxing Formation bio-reef reservoirs in the Longhuichang-Tieshan area of the northeastern Sichuan Basin, China, and to elucidate the relationship between these reservoirs and gas distribution. Utilizing drilling and logging data, this study provides a comprehensive summary of the seismic geological characteristics of bio-reef reservoirs. Furthermore, it investigates the effects of reservoir parameters, structural location, and strike-slip faults on the development of bio-reef gas reservoirs. The research shows that bio-reef reservoirs in the area predominantly manifest vertical development in the middle and upper parts of the Changxing Formation, with horizontal expansion occurring along the platform margin and local highland areas. Notably, potential exploration areas are identified, particularly the western wing of the Longhuichang structure and the southwestern side of the Tieshannan structure. By comparing and analyzing the relationship between bio-reef gas reservoirs in the study area, the study aims to clarify the controlling effects of reservoir parameters, structural location, strike-slip faults, and other pertinent factors on the development of bio-reef gas reservoirs. It is observed that while these factors do not exhibit a clear strong linear relationship, they have a comprehensive effect on the development of gas reservoirs. The enrichment mode and failure mode of favorable gas reservoirs in the study area have been analyzed and established, providing crucial technical support to facilitate further exploration of Changxing Formation bio-reef gas reservoirs in the northeastern Sichuan Basin.

近期,中国石油部署于四川盆地东部地区(下文简称川东地区)的风险探井——大页 1H井,经测试在二叠系吴家坪组三段深水陆棚相页岩测试获 32.06×104 m3/d的高产工业气流,开辟了页岩气勘探开发新领域.为了进一步明确四川盆地二叠系海相页岩气的勘探方向和资源潜力,基于大页 1H井钻录试井资料,以开江—梁平海槽内二叠系吴家坪组海相页岩为研究对象,开展了有机地球化学、储层特征、脆性矿物含量和含气性等含油气地质条件研究,指出了该新领域页岩气的勘探开发前景.研究结果表明:①开江—梁平海槽在吴家坪组沉积时期为深水陆棚相沉积环境,槽内沉积了一定厚度、分布稳定的富有机质(TOC＞2%)页岩;②吴家坪组具有良好的页岩气富集成藏地质条件,其中吴家坪组三段(下文简称吴三段)最佳,大页 1H井吴三段有机碳含量平均值高达 9.83%,有机质内部发育不同程度的有机质孔,孔隙发育,平均孔隙度 6.40%,为优质储层;③大页 1H井吴三段页岩平均脆性指数达 85%,可压裂性好,平均含气量高达 10.39 m3/t,页岩总含气量高;④川东地区吴家坪组海相页岩具有良好的页岩气勘探开发潜力,其中吴家坪组埋深 4 500 m以浅面积超过 1 400 km2,估算地质资源量约 4 500×108 m3,可供勘探区内吴家坪组埋深 5 000 m以浅面积超过2 880 km2.结论认为,大页 1H井的突破开启了四川盆地开江—梁平海槽二叠系海相页岩气规模增储上产的新篇章,进一步拓展了四川盆地页岩气的工作对象,对夯实四川盆地天然气资源基础和保障国家能源安全具有重要意义.

近期,部署实施于四川盆地德阳—安岳裂陷西侧(以下简称裂陷西侧)的风险探井大探1井,在震旦系灯影组二段、灯影组四段(以下简称灯二段、灯四段)分别测试获天然气42×104 m3/d、81×104 m3/d,取得了裂陷西侧天然气勘探的重大战略突破.为了评价裂陷西侧灯影组沉积、储层和油气成藏地质条件,通过对野外露头、岩心、薄片及测试资料等进行分析,重新厘定了区内老井地层、沉积格局、有利区带展布特征,深化了裂陷西侧灯影组油气成藏地质认识,指导了下一步天然气勘探.研究结果表明:①裂陷西侧震旦系地层完整、序列齐全,灯影组地层广泛分布,灯四段与麦地坪组呈整合接触,桐湾Ⅱ幕位于麦地坪组顶部,因此灯影组未遭受到广泛剥蚀;②裂陷西侧灯二段、灯四段丘滩体面积分别约为3 000 km2、4 000 km2,丘滩相储层特征与裂陷东侧基本一致,储集岩均以凝块白云岩和砂屑白云岩为主,差异主要体现在西侧灯影组渗透性更高,并发育大量晚期网状缝,此与该区受晚期强烈挤压密切相关;③川西南地区发育中元古界峨边群、震旦系陡山沱组、寒武系筇竹寺组3套烃源岩,受晚期构造挤压,通源断裂发育,3套烃源岩与灯影组形成下生上储、侧生旁储、上生下储高效天然气成藏组合;④大探1井所在的大兴场构造具备双层构造体系特征,保存条件好,而且关键成藏期位于古构造高部位,早期普遍成藏,晚期调整定型,具备规模成藏的含油气地质条件;⑤提出了非继承性构造演化区,在正向地质单元寻找规模化的滩带,在负向地质单元寻找烃源岩的勘探思路,并建立了"滩带—断层—烃源"跨时空配置成藏新模式.结论认为,大探1井在裂陷西侧灯影组天然气勘探取得的重大突破,进一步展示了该区巨大的天然气勘探潜力,且该区有可能成为继安岳气田之后一个重要的天然气开发主战场.

CORRECTION article Front. Earth Sci., 23 May 2023Sec. Structural Geology and Tectonics Volume 11 - 2023 | https://doi.org/10.3389/feart.2023.1201571

四川盆地下古生界寒武系沧浪铺组勘探潜力巨大.文中结合钻井和野外地质剖面实测成果等最新资料,研究了四川盆地北部地区沧浪铺组沉积演化规律.结果表明:1)沧浪铺组沉积期,研究区内可识别出开阔台地相、局限台地相和潮坪相3种沉积相类型,纵向上具有明显的分异特征,横向上沉积厚度西薄东厚.沧一段沉积期,开阔台地相发育以鲕粒石灰岩、砂屑石灰岩为主要岩性并可见小型槽状交错层理的台内滩亚相,和以泥晶石灰岩为主要岩性的滩间海亚相;局限台地相发育以具有残余结构的砂屑白云岩和鲕粒白云岩为岩性并可见重结晶作用的台内滩亚相,和以灰质泥晶白云岩、砂质白云岩为主要岩性的滩间海亚相;在裂陷槽和古隆起之间区域,发育以泥质白云岩、泥灰岩和砂质白云岩为主要岩性的混积潮坪相.沧二段沉积期,发育以紫红色泥岩、砂岩等为主要岩性的碎屑潮坪相,见小型水平层理、羽状交错层理和砂岩透镜体.2)沧浪铺组沉积期,以大规模海退为主,水体总体逐渐变浅.沧一段沉积期,碎屑物质输入受到裂陷槽隔档作用影响,发育碳酸盐岩沉积,在构造高部位发育以颗粒岩为主的台内滩亚相.至沧一段沉积末期,裂陷槽逐渐被填平,碎屑物质得以向东持续迁移.沧二段沉积期,发生了小规模的海侵—海退过程,水体由深变浅,最终形成以砂泥岩互层沉积为主要特征的碎屑潮坪沉积环境.

三维地震勘探常常处于城镇、道路等无法实施微测井等静校正方法的区域,近期人们尝试利用微动调查替代现有的静校正方法,取得了一定效果.现今微动调查在石油勘探的应用中主要通过提取面波频散曲线反演地层速度结构.该方法在石油勘探领域仍处于起步阶段,作为核心技术的频散成像方法种类繁 多,其中2019年提出的频率—贝塞尔变换法(Frequency-Bessel,F-J)受到人们的广泛关注.相比空间 自相关方法(SPAC),F-J方法在利用背景噪声高阶模式面波成像上具有巨大优势.为了更好地研究F-J方法的适用性,首先利用合成数据分析了不同观测系统和采集参数对F-J成像的影响;然后利用四川某地实际噪声数据分析了不同观测系统、采集时间对F-J频散成像的影响.实际应用中采用分段择优叠加得到的频散谱,可有效提高频散谱成像质量,为准确提取频散曲线提供了数据基础.进一步对比测井数据,发现利用基阶、高阶模式频散曲线进行多模式联合反演可精确地反演地层结构,使经济、高效地获得表层结构成为可能.

High-quality seismic data is key to determining the success or failure of oil and gas exploration in complex mountain fronts. Observation systems are important factors affecting the quality of the seismic collection. Currently, the seismic collection design of piedmont zones is mainly based on optimizing and analyzing a single collection parameter. The multiparameter optimization is not performed as a whole. Moreover, the collection parameters that significantly impact the imaging quality of piedmont zones are not deeply excavated. This paper first uses the relationship between the acquisition parameters and the signal-to-noise ratio of a previous seismic data analysis to solve this problem and then obtains the prestack offset profiles of different acquisition parameters through forward modeling and prestack offset methods, further analyzes the acquisition parameters that have a more significant impact on imaging quality, uses the degenerative treatment method to process and analyze the newly collected seismic data, and delves into the most sensitive acquisition parameters for imaging quality. The results show that the influence of the gun line distance is the largest, and the influence of the receiving line distance, the number of receiving lines, and the number of receiving channels is reduced. Therefore, the effect of each acquisition parameter on the imaging quality is different, and different acquisition parameters should be selected according to the depth of the target layer.

1.目的 随着四川盆地油气勘探目标向隐蔽性地质目标转移,对地震资料保真度和分辨率提出更高要求.地震检波器是油气地震勘探关键设备之一,直接关系到地震资料品质的优劣.理想条件下,检波器接收到的信号反映了表土真实的机械振动情况,但实际的地震波接收过程受检波器自身性能及检波器表土耦合问题的制约,会影响接收到的地震波动力学特征信号.因此,笔者基于外界噪声投射原理、检波器与表土耦合响应影响因子分析,提出了四川盆地地震采集检波器"体耦合"埋置技术.

In this paper, taking the first Member of the Canglangpu Formation of the Cambrian Terreneuvian in the northern central Sichuan Basin as an example, the diagenesis and its influence on porosity are systemically studied based on the observations and identifications of cores, casts and cathodoluminescence thin sections. The results show that the rock types of the first member of Canglangpu Formation are various, including mixed rocks, carbonate rocks and clastic rocks. The specific lithology is dominated by sand-bearing oolitic dolomite, sandy oolitic dolomite, sparry oolotic dolomite and fine-grained detrital sandstone. At the same time, the Cang 1 Member has experienced five types of diagenetic environments, including seawater, meteoric water, evaporative seawater, shallow burial, and medium-deep burial diagenetic environments. Moreover, the main diagenetic processes under different diagenetic environments include cementation, dissolution, compaction, chemical compaction, dolomitization and structural fractures. According to the analysis, fabric-selective dissolution in meteoric water diagenetic environment, dolomitization in evaporative seawater environment, and non-fabric-selective dissolution, dolomitization and structural fractures in buried diagenetic environment are beneficial to the development of pores. However, cementation, compaction and chemical compaction in medium and deep burial environments, are unfavorable for the development of pores.

The early CambrianQiongzhusi Formation shale is richin organicmatter and is a high-quality marine Source rock. However, the originof Qiongzhusi Formation siliceous rocks is unknown, and the role ofsiliceous rocks in the process of organic matter enrichment or preservationis also lacking. This study combines thin section, scanning electronmicroscopy, SEM/EDS, major and trace element analysis, and N-2 adsorption experiments to analyze and evaluate the shale of theQiongzhusi Formation in the central region of the Sichuan Basin. Thequartz types in the shale of the Qiongzhusi Formation are dividedinto four types, namely, bioclastic siliceous rocks, terrestrial detritalquartz, siliceous microcrystalline quartz particles, and microcrystallinequartz aggregates; at the same time, according to petrographic andgeochemical parameters, the content of authigenic quartz in QiongzhusiFormation shale decreases from top to bottom, and terrigenous detritalquartz tends to increase, and biogenic silicon accounts for the majorityof authigenic quartz components; autogenous quartz has a positiveimpact on the pore structure of shale, providing sufficient pore spacefor the development of organic pores and protecting the internal porenetwork by forming intergranular pores as rigid frameworks. At thesame time, it plays a crucial role in the enrichment and preservationof organic matter.

以古生界为主的海相碳酸盐岩是我国陆上油气勘探的重点领域,勘探开发成效显著.随着勘探不断发展,超深层、更古老海相层系油气成藏富集规律的认识面临挑战.本文从古老小克拉通盆地构造分异的角度,剖析油气成藏富集规律.通过对四川、塔里木和鄂尔多斯等克拉通盆地演化过程中的构造分异作用研究,认为克拉通盆地构造分异对沉积、成储与成藏组合有显著的控制作用.构造分异控制的三类油气聚集带是未来超深层海相碳酸盐岩油气勘探的重点领域.

ST9井测试获气进一步展示了川西复杂构造带二叠系具有较大的勘探潜力,但由于龙门山推覆构造地层破碎,地震波场畸变,地震数据品质低,难以满足后续地震地质解释研究的需求,因此如何提高该区地震数据采集及成像质量尤为重要.针对这一问题,以HX1井区资料为基础,建立地质模型,从地下目的层成像角度优选采集参数,总结分析川西复杂构造带不同激发区域地震波场特征差异,利用照明能量优化采集参数和激发区域,深入分析对成像质量最为敏感的采集参数,分区域提出观测系统建议方案,研究认为炮点距(或炮线距)对成像质量的改善最为敏感,龙门山构造主体应进行局部加密炮点距(或炮线距),而盆地内激发效果好,但对改善龙门山主体构造的成像质量作用不大,可以降低炮点密度,从而通过有目标的疏密炮点设计方法,经济高效地提高研究区主体构造成像质量.

The high-yield reservoir test of the second member of the Dengying Formation in the Zhongjiang-Penglai area shows great exploration potential. Due to the dual effects of sedimentation and dissolution， the reservoir heterogeneity is strong and the gas-water relationship is complex. In addition to the development of dense zones in the horizontal direction， there are also dense area barriers in the vertical direction， forming multiple independent gas reservoirs with different gas-water interfaces. In this regard， based on the seismic geological characteristics of drilled wells， this paper intends to establish the seismic identification model of Dengying reservoir and dense area， and then deeply analyze the sedimentary evolution process of paleogeomorphology in the upper sub-member of Dengying Formation， finely characterize lithologic traps， and clarify the spatial distribution law of effective reservoirs. The study shows that the high-quality reservoir of the hilly-Shoal reservior is developed in the second member of 2 layers of the upper sub-member of Deng 2， with a thickness of 30-110 m. Laterally， it is developed in the high landform area near the platform margin， showing a continuous distribution characteristics. The dense area develops in the low part of paleogeomorphology， and has a good coupling relationship with rift of Sinian System， which has a shielding effect on gas reservoir. The practice shows that the understanding in this paper is highly consistent with the actual drilling， which can provide technical support for the exploration of Dengying Formation gas reservoir in the northern slope.

由于川中高磨地区灯影组超深层碳酸盐储层横向非均质性强、缝洞较发育、地震分辨率低、优质储层地球物理特征认识不清等突出问题,造成了储层预测不准、探井工艺井储层钻遇率不高等难题,影响勘探评价效果.通过研究超深碳酸盐优质储层及致密层的地震响应特征,以导眼井电测声波数据为基础,构造不同的地质模型,正演不同地质条件下的合成地震记录,总结出不同地质组合关系下的储层地震响应记录,并与实际地震记录比对分析,确定优质储层的横向展布特征,为工艺井的部署及随钻决策提供依据,降低钻井风险.经过实际工艺井钻井实时跟踪分析的验证,本方法有效地提高了工艺井优质储层钻遇率,达到了勘探目标评价效果.

为了刻画川西南部地区二叠系火山岩相展布、厘清其分布主控因素,基于已钻井火山岩地球物理响应特征分析,结合火山机构模型正演,明确不同火山岩相所对应的地震响应特征,进而采用多信息地震属性技术预测火山岩相展布;结合火山岩相、基底断裂、古地貌等信息研究火山岩相分布主控因素.研究结果表明,川西南部BMM地区发育规模性火山岩爆发相发育区,面积达500 km2,是四川盆地火山岩油气勘探区带拓展的有利区.火山岩相分布主要受基底断裂及火山喷发前古地貌控制.