针对二叠系的构造—沉积演化过程复杂、有利相带展布格局恢复困难及有利勘探区带不明朗等问题,利用近年新的二维和三维地震资料、盆缘野外及盆内钻井、录井资料,开展四川盆地二叠系构造沉积演化的系统研究,探索主要构造运动的响应特征及影响因素,建立各组、段之间的连续沉积演化关系,明确多套目的层系的有利沉积相带展布,为有利勘探区带的优选提供重要支撑。通过地质特征综合分析,认为：①二叠系沉积前古地貌、二叠纪拉张构造背景、地幔柱隆升及火山喷发等多种因素,造成了二叠系构造沉积分异;②四川盆地二叠纪表现为区域拉张构造动力背景,属克拉通裂陷盆地沉积体系,控制了多个层系边缘礁滩相带的展布,为发育规模岩性圈闭群奠定了基础;③三叠纪早期继承了二叠纪末期沉积格局,并受盆地边缘古陆、岛链、水下隆起影响,整体呈现填平补齐的特征,属克拉通坳陷盆地沉积体系,滩体受微地貌控制呈垂向加积、侧向进积的特点,平面上在清水台地区大面积席状展布;④基于构造—沉积背景分析以及二维和三维地震资料的综合应用,明确了栖霞组“一缘两环带”,茅口组“一隆一缘”,长兴组“三隆三洼”,飞仙关组“三隆成滩、三洼补齐”等主要沉积面貌。综合含油气地质条件分析,指出川西地区栖霞组台缘带及川中—蜀南地区台内高带,剑阁—南充—石柱地区茅口组台缘带,开江—梁平地区海槽及蓬溪—武胜—石柱地区浅水陆棚长兴组边缘礁滩等,是四川盆地二叠、三叠系的主要勘探领域和方向。

The Permian system in Sichuan Basin is complex in tectono-sedimentary evolution, creating difficulties in restoring the distribution of favorable facies zones and uncertainties in favorable exploration belts. So, through the latest 2D and 3D seismic data as well as drilling and mud-logging data in and around the basin, this evolution was investigated systematically to identify response characteristics and influential factors of major tectonic movements. The relationship of continuous sedimentary evolution was established to every formation and member and the distribution of favorable facies zones with multiple targets was defined to provide an important support for optimizing the favorable exploration belts. After the comprehensive analysis on geological characteristics, it is revealed that (i) multiple factors, including ancient landform before the Permian deposition, and tensile tectonic setting, mantle plume uplift and volcanic eruption in the Permian, affect the tectonic-sedimentary differentiation of the Permian; (ii) representing a regional tensile tectonic setting, the Permian in Sichuan Basin was a sedimentary system of cratonic rifted basin, which controlled the distribution of bioreef-beach facies zones on the margin of multiple strata, laying a foundation for the development of massive lithologic traps; (iii) in the early Triassic, the basin inherited the sedimentary pattern in the late Permian, and exhibited one feature of filling and leveling up due to some effects, for example, ancient land, island chain and underwater uplift at the basin margin. It was a sedimentary system of cratonic depression basin, whose beaches in vertical and lateral accretion might be controlled by microgeomorphology and presented large-scale sheet-like distribution in Qingshuitai area in plane; and (iv) dependent on the analysis of tectono-sedimentary setting and the comprehensive application of 2D and 3D seismic data, the main sedimentary features were defined, such as “one margin and two ribbons” in Qixia Formation, “one uplift and one margin” in Maokou Formation, “three uplifts and three depressions” in Changxing Formation, and “three uplifting forming beaches and three depressions filling and leveling up” in Feixianguan Formation. In addition, the analysis of petroleum geology points that the main exploration domains and prospects of Permian and Triassic in Sichuan Basin will focus on the platform margin zone of Qixia Formation in western basin, the intraplatform highland zone in central-southern basin, the platform margin zone of Maokou Formation in Jian’ge-Nanchong-Shizhu area, the trough in Kaijiang-Liangping area, and the bioreef-beach on the edge of Changxing Formation in shallow shelf of Pengxi-Wusheng-Shizhu area.

借鉴普光气田勘探发现的成功经验,2006年中国石油化工股份有限公司在川东北巴中地区钻探以长兴组—飞仙关组生物礁、滩岩性圈闭为目标的元坝1井,获得50.3×10⁴m³/d高产工业气流,发现了元坝气田。元坝气田为常压高含硫化氢岩性气藏,具有构造变形弱、整体埋藏深的特点,气藏中部平均埋深6 600 m,是四川盆地埋藏最深的海相气田。元坝气田以长兴组礁滩储层为主,其规模大、储集性良好,储层的形成主要受早期大气淡水溶蚀、白云石化作用控制,深埋溶蚀、构造作用影响相对较弱。对元坝、普光等气田深层礁滩相储层特征进行对比,探讨其储层形成机理,认为早期沉积-成岩环境控制了储层的规模与早期孔隙发育,构造-流体耦合控制了裂缝与溶蚀,流体-岩石相互作用控制了孔隙的保存与改造。

According to successful exploration experience in Puguang gas field, the China Petroleum and Chemical Corporation(Sinopec) successfully drilled Well YB1 in 2006 by targeting biogenic reef and shoal lithologic shoal in the Feixianguan-Changxing Formation in the Bazhong area, northeastern Sichuan Basin, China. The Well YB1 produced a high-yield industrial gas flow of 503 000 m³/day, representing the discovery of Yuanba gas field. This new gas field mainly comprises of normal-pressure, high-H₂S lithologic gas reservoirs characterized by weak tectonic deformation and overall deep depth. The mean depth is approximately 6600 m in the central part of the reservoirs, representing the deepest marine reservoirs discovered in Sichuan Basin to date. Dominant reef-shoal reservoirs of the Changxing Formation are widely distributed with high porosity and permeability, whose formation were mainly controlled by early meteoric dissolution and dolomitization associated with weak burial dissolution and tectonic action. The characteristics of deep reef-shoal reservoirs in Yuanba and Puguang gas fields are compared to explore their formation mechanisms. Evidence shows that: (1) Early depositional and diagenetic environment controlled reservoir scale and early pore formation; (2) The coupling of tectonics with fluid activities regulated fracturing and dissolution; and (3) fluid-rock interactions determined the transformation and preservation of pores.

通过岩心观察、微观薄片鉴定、扫描电镜等资料，在层序划分基础上对四川盆地开江—梁平海槽东侧飞仙关组的储层特征及控制因素进行了研究。研究结果表明： ①铁山坡—普光地区飞仙关组储层以鲕粒云岩和细粉晶白云岩为主，渡口河—七里北地区以（含砾屑、砂屑、豆粒）鲕粒白云岩为主，鲕粒岩原始结构组分保存更好。②研究区储层具有多期次发育特征，铁山坡—普光地区储层在ssq1，ssq2，ssq3层序均有分布，具有发育早、厚度大、分布面积广的特征，Ⅰ，Ⅱ，Ⅲ类储层均发育；渡口河—七里北地区储层发育在ssq2，ssq3层序，发育较晚、厚度小、分布面积有限，以Ⅱ，Ⅲ类储层为主。③研究区沉积古地貌及海平面升降控制了鲕滩储层发育的期次、厚度等，在ssq1沉积中晚期海平面开始下降时，古地貌高地开始发育鲕滩储层，厚度大，白云石化作用明显。④研究区内陡坡型和缓坡型台缘斜坡带，水体能量的强弱控制了鲕滩沉积物类型，为成岩期溶蚀作用和白云石化作用奠定了物质基础，进而控制了储层的物性和规模。

Based on core observation, micro thin section identification and scanning electron microscope analysis, combined with sequence division, the reservoir characteristics and controlling factors of Triassic Feixianguan Formation in eastern Kaijiang-Liangping trough of Sichuan Basin were studied. The results show that:(1) The reservoirs of Triassic Feixianguan Formation are dominated by oolitic dolomite and fine silty dolomite in TieshanpoPuguang area, and oolitic dolomite(with gravel, sand and bean grains) in Dukouhe -Qilibei area, and the original structural components of oolitic rocks are better preserved.(2) The reservoirs in the study area are characterized by multi-stage development. The reservoirs in Tieshanpo-Puguang area are developed in ssq1, ssq2 and ssq3 sequences, with the characteristics of early development, large thickness and wide distribution area, and type Ⅰ, Ⅱ and Ⅲ reservoirs are developed. The reservoirs in Dukouhe Qilibei area are developed in ssq2 and ssq3 sequences, which are late developed, small in thickness and limited in distribution area, and are dominated by type Ⅱ and Ⅲ reservoirs.(3) Sedimentary palaeogeomorphology and sea-level change control the development stages and thickness of oolitic shoal reservoirs in the study area. When sea-level began to decline in the middle and late stages of ssq1, oolitic shoal reservoirs began to develop in the paleogeomorphic highlands with large thickness and obvious dolomitization.(4) The water energy in steep slope and gentle slope margin slope zones affects the types of oolitic shoal sediments, provides a material basis for diagenetic dissolution and dolomitization, and thus controls the physical properties and scale of the reservoir.

　四川盆地东北部宣汉县樊哙以东地区晚二叠世—早三叠世飞仙关期碳酸盐岩台地相—海槽相剖面均出露地表。分隔台地相和海槽相的碳酸盐岩斜坡相的鸡唱剖面距台地边缘相剖面不足１ｋｍ。根据地面露头碳酸盐岩斜坡相带的特征，可在四川盆地北部环开江—梁平海槽的地震反射剖面上有效地识别出碳酸盐岩斜坡相，并划分出浅水、深水碳酸盐沉积区。斜坡相具有明显的倾斜反射，海槽相区大隆组及飞仙关组底部泥岩的强振幅反射在斜坡下部向台地上超并消失。深水相区上二叠统地震波双程反射时间都小于１００ｍｓ且明显短于飞仙关组，而台地相区上二叠统双程反射时间多大于１５０ｍｓ，且与上覆飞仙关组地震波反射时间相近或略长。碳酸盐岩斜坡相倾斜反射的特征表明环海槽的碳酸盐岩斜坡开始发育于晚二叠世中期，并随海侵向碳酸盐岩台地方向迁移，在晚二叠世末期海侵达到顶峰时形成最陡峭的斜坡。飞仙关期斜坡随海平面缓慢下降而逐渐向海槽方向迁移并变缓。晚二叠世末期海槽南端梁平地区斜坡坡度在３°左右，向北东、北西方向变陡，宣汉地区约２０°，苍溪、仪陇地区最高达４０°以上，海槽呈向北逐渐加深的箕形。根据晚二叠世末期斜坡倾斜反射高度计算，开江—梁平海槽的水深在３５０～４５０ｍ左右。苍溪、仪陇及梁平地区飞仙关组斜坡进积明显，宣汉地区的斜坡以加积为主。目前钻遇的最厚鲕滩储集层位于宣汉加积斜坡附近的台地边缘，单井的鲕粒白云岩储集层厚度超过３００ｍ。

<p>The carbonate platform and trough facies of the Late Permian to the Early Triassic Feixianguan Formation are outcropped in the east Fankuai in Xuanhan County, northeastern&nbsp; Sichuan Basin. The distance between the Jichang carbonate slope facies section which separates the platform facies and trough facies， and the platform margin facies section is less than one kilometer. According to the characteristics of the outcrops of carbonate slope facies，&nbsp; the carbonate slope facies can be identified on the seismic sections of KaijiangLiangping trough in northern Sichuan Basin and the shallow water carbonate sedimentary area and deep water carbonate sedimentary area was subdivided. Slope facies is characterized by the obvious inclined reflection. High amplitude reflection caused by the mudstone of Dalong Formation and the bottom of the Feixianguan Formation of the trough facies onlapped towards the platform and disappeared. The twoway travel time of trough facies in the Upper Permian is less than 100 ms and is far less than that of the Feixianguan Formation， while the twoway travel time of platform facies is more than 150 ms which is similar to or slightly longer than that of the Feixianguan Formation. The incline reflection characteristics of slope facies,&nbsp; indicate that the carbonate slope of KaijiangLiangping trough was developed in the middle Late Permian and migrated to the carbonate platform with transgression occurred. It became the steepest slope when the transgression reached the maxium at the end of the Late Permian. In the Feixianguan Period， slope gradient decreased with the sea level fall and the slope migrated to the trough. At the end of the Late Permian， the slope gradient of Liangping area which is the south of the trough was around 3&deg;and slope became steep towards the northeast and northwest. In the Xuanhan area， the slope gradient was about 20&deg;， and it achieved the highest gradient of&nbsp; 40&deg; in Yilong area. The trough was a basin which became deeper to wards the north. According to the height of the inclined reflection of slope in the Late Permian， it is calculated that the depth of the KaijiangLiangping trough was around 350 to 450 meters. The slopes are characterized by obvious progradation of the Feixianguan Formation in Cangxi， Yilong and Liangping areas and the slope is dominated by aggradation in Xuanhan area. The currently drilled thickest oolitic beach reservoir is located in the platform margin adjacent to the aggradational slope in Xuanhan area. The thickness oolitic dolomite reservoir in individual wells is larger than 300 meters.</p>

近年关于四川盆地飞仙关组鲕滩的勘探开发多集中在开江梁平海槽两侧,为进一步拓展盆地内飞仙关组鲕滩发育有利区,利用大量新采集的盆地大格架剖面和二维、三维地震资料,充分结合地质认识、钻井资料和测井资料,开展了川中川东地区飞仙关组鲕滩分布规律研究。通过优选整个四川盆地飞仙关组井位,精细标定鲕滩储层在不同相区的地震剖面上的响应特征和发育位置,结合盆地大格架剖面上飞仙关组沉积特征,建立了飞仙关组鲕滩从盆地中部到川东北地区的发育模式,发现了四川盆地飞仙关组鲕滩分布及迁移规律,提出了鲕滩储层发育是受物源方向和裂陷槽联合控制的沉积模式的地质新认识。研究认为四川盆地飞仙关组鲕滩具有&ldquo;自西南向东北方向&rdquo;迁移的特征,川中川东地区沿蓬溪武胜台凹和开江梁平海槽发育3期大规模鲕滩:飞一段前积鲕滩体,飞二、飞三段前积鲕滩体和飞二、飞三段加积鲕滩体,川中中部蓬溪武胜台凹处也发育与开江梁平海槽两侧一样的飞仙关组高能鲕滩储层,这一发现为飞仙关组地层的勘探提供了新的勘探区域,具有重要的勘探价值。

In recent years,the exploration and development of the oolitic beaches of the T1f Formation in the Sichuan Basin has been focused on the two sides of the Kaijiang-Liangping trough.To identify additional favorable locations,the spatial distribution of these beaches in central and east Sichuan was investigated using a large number of newly collected large-scale frame lines and two-and three-dimensional seismic data,which were combined with drilling and logging data and a geological model.The well locations within the T1f Formation were optimized across the entire Sichuan Basin,and a fine characterization of the response and development of the oolitic beach reservoirs in areas with different facies was achieved.The sedimentary characteristics of the T1f Formation in the Daggejia section of the basin were also analyzed.Based on these insights,a spatial distribution and migration model for the T1f oolitic beaches was established,together with a development model spanning from the center to the northeast of the basin.A new geological understanding was proposed,which suggests that the development of the oolitic beach reservoirs is jointly controlled by the direction of provenance and the rifting trough.It was shown that the beaches have experienced northeastward migration.The beaches along the Pengxi-Wusheng platform sag and the Kaijiang-Liangping trough could be grouped into three development stages,namely:the Feiyi pre-oolitic beaches,the Feier and Feisan pre-oolitic beaches,and the Feier and Feisan oolitic beaches.High-energy oolitic beach reservoirs of the same type as those found on the two sides of the Kaijiang-Liangping trough were also found in the Pengxi-Wusheng platform sag in the central part of the basin,indicating the possibility of a new and valuable exploration area.

川西北九龙山地区三叠系飞仙关组二段在天然气勘探中取得重大突破，具有较大的勘探潜力。井下钻探资料显示飞仙关组二段（简称飞二段）发育多套储层且主要集中于飞二上亚段，整体非均质性较强，岩性、物性复杂多变，储层厚度较薄、钻井较少，难以明确鲕滩储层的空间展布特征，制约着该区天然气勘探进程。针对川西北九龙山地区飞二上亚段鲕滩储集层，利用井下储层特征及三维地震资料，分析鲕滩储层反射特征，再利用正演模拟，建立鲕滩储层地震响应模式，明确该区鲕滩储层地震响应特征为弱振幅—断续反射；通过采用层拉平印模法恢复飞二段古地貌，结合地震相分析及地震振幅属性特征，确定了鲕滩体发育有利相带分布特征。在有利相带分布的基础上，利用以相对阻抗为主的调谐振幅反演及波形差异反演方法对储集层空间展布进行精细预测，明确了储集层的空间展布特征，同时对鲕滩储层厚度及裂缝发育进行了预测，其储层厚度预测结果与实钻结果较为吻合，证实了该预测方法在该地区具有适用性，并根据裂缝发育、波阻抗值小于1.6×10⁶ g/（cm²·s）、储层厚度大等指标进一步圈定鲕滩储层有利发育区，为下一步勘探开发提供有利依据。

The second member of Feixianguan Formation of Triassic in Jiulongshan area of northwestern Sichuan has made major breakthroughs in natural gas exploration and has great exploration potential. Drilling data show that the second member of Feixianguan Formation has developed multiple sets of reservoirs， which are mainly concentrated in the upper sub-member of second member of Feixianguan Formation. The overall heterogeneity is strong， the lithology and physical properties are complex and changeable， the reservoir thickness is thin， and drilling is less， so it is difficult to determine the spatial distribution characteristics of oolitic beach reservoir， which restricts the natural gas exploration process in this area. For oolitic beach reservoir in the upper sub-member of the second member of Feixianguan Formation of Jiulongshan area， using downhole reservoir characteristics and 3D seismic data， the reflection characteristics of oolitic beach reservoir are analyzed， and then the seismic response model of oolitic beach reservoir is established by forward modeling. It is clear that the seismic response characteristics of the reservoir in this area are weak amplitude-continuous reflection； through the use of layer flattening impression method to restore the ancient landscape of the second section of Feixianguan Formation， combined with seismic facies analysis and seismic amplitude attribute characteristics， the distribution characteristics of favorable facies belt for oolitic beach development are determined. On the basis of the distribution of favorable facies belt， this paper uses the relative impedance based on tuning amplitude inversion and waveform difference inversion method to make a fine prediction of the spatial distribution of the reservoir， defines the spatial distribution characteristics of the reservoir， and predicts the thickness and fracture development of oolitic beach reservoir. The prediction results of the reservoir thickness are in good agreement with the actual drilling results， which confirms the application of this prediction method in this area. According to the fracture development， wave impedance value less than 1.6×10⁶ g/（cm²·s）， reservoir thickness and other indicators， the favorable development area of oolitic beach reservoir is further delineated， which provides a favorable basis for the next exploration and development.

四川盆地东北部七里北—渡口河地区飞仙关组具有较大的油气勘探开发潜力,但高频旋回地震识别及追踪难度大,多期次滩体纵向叠置,储层横向非均质性强,未形成配套的迁移型鲕滩储层分期地震预测方法。针对高频旋回地震识别追踪和鲕滩储层分期地震预测难度大的问题,基于不同地震反射相带分区的方法,进行飞仙关组内部旋回横向精细追踪,精细预测飞仙关组多期次鲕滩储层。研究表明:基于不同地震反射相的层序地层地震反射界面追踪对比法,可以有效地解决高频层序界面识别难题,飞仙关组划分出双轴强反射、内部弱反射、单轴强反射、杂乱-亚平行反射和多轴强反射5类反射地震相;利用振幅和弧长敏感属性定性及神经网络反演定量预测成果,明确优质储层主要发育在Ⅱ旋回,从Ⅱ旋回到Ⅲ旋回,储层具有自东向西、从台地向海槽不断迁移进积发育的规律。实践表明,不同地震反射相的层序地层地震反射界面追踪对比,结合敏感属性控制的储层预测方法,针对迁移型鲕滩储层具有较好的适用性。该研究对同类型气藏储层精细预测具有一定的借鉴意义。

开江-梁平海槽中-北段飞仙关组鲕滩气藏勘探已在多个区块取得重大突破，而海槽南段的勘探进展有限，其储层面貌及分布的控制因素不明确。基于录井、岩心、岩石薄片和碳、氧、锶同位素、主量与微量元素等测试资料，根据矿物组成、晶粒大小和孔隙成因类型，在开江-梁平海槽南段飞仙关组鲕滩识别出粒间孔型鲕粒灰岩（A型）、铸模孔型鲕粒灰岩（B型）、粒间溶孔型鲕粒白云岩（C型）、铸模孔型鲕粒白云岩（D型）、细晶白云岩（E型）和粉晶白云岩（F型）6种储集岩类型以及鲕粒灰岩储层、鲕粒白云岩储层和晶粒白云岩储层3类储层。鲕粒灰岩储层分布在台缘带和台内。台缘带鲕粒灰岩储层岩石类型为粒间孔型鲕粒灰岩，储集空间以残留粒间孔为主；台内鲕粒灰岩储层岩石类型为铸模孔型鲕粒灰岩，储集空间主要为铸模孔或粒内溶孔。鲕粒白云岩储层仅发育在台缘带，储集岩类型为粒间溶孔型鲕粒白云岩或粒间溶孔型鲕粒白云岩与铸模孔型鲕粒白云岩的组合。晶粒白云岩储层仅在台缘带发育，储集岩类型为细晶白云岩或粉晶白云岩，储集空间以晶间孔为主。飞仙关组鲕滩储层整体为低孔、低渗，鲕粒白云岩储层与晶粒白云岩储层、细晶白云岩与粒间溶孔型鲕粒白云岩的储集物性相对较好。组构选择性溶蚀作用和同生成岩阶段-早成岩阶段中等盐度海水主导的渗透回流白云石化作用是飞仙关组鲕滩储层与储集岩类型多样化及其分布规律的主要控制因素。

The exploration of oolitic shoal gas reservoir in from the middle part of Kaijiang-Liangping trough to the northern Feixianguan Formation has made great breakthroughs in many areas, while the exploration progress in the southern part of the trough in eastern Sichuan Basin has been impeded by a unclear understanding of the reservoir landscape and controlling factors of reservoir distribution. Based on the test data of well logging, core, rock thin section, carbon, oxygen and strontium isotopes, and major-trace elements, according to mineral composition, grain size and genetic type of pores, we identified the oolitic limestone with intergranular pores (Type A) and moldic pores (Type B), the oolitic dolostone with intergranular dissolution pores (Type C) and moldic pores (Type D), the fine crystalline dolostone (Type E), and the powder crystalline dolostone (Type F), thus forming three types of reservoirs such as oolitic limestone, oolitic dolostone and crystalline dolostone. Of these, oolitic limestone reservoirs are distributed in the platform and its margin. The oolitic dolostone reservoir in the platform margin belongs to Type A, and the reservoir space is dominated by residual intergranular pores; the intra-platform oolite limestone reservoir belongs to Type B, and the reservoir space is dominated by moldic pores or intragranular dissolved pores. Oolitic dolostone reservoirs are only developed in the platform margin, composed of Type C oolitic dolostone, or a combination of Type C oolitic dolostone and Type D oolitic dolostone. Crystalline dolostone reservoirs are only developed in the platform margin, composed of the fine crystalline dolostone (Type E) or powder crystalline dolostone (Type F), dominated by intercrystalline pores. The oolitic shoal reservoir in Feixianguan Formation is generally characterized by low porosity and permeability. Better physical properties are observed in oolitic dolostone reservoirs, crystalline dolostone reservoirs, fine crystalline dolostones and Type C oolitic dolostone. The fabric-selective dissolution and seepage-reflux dolomitization dominated by comtemporaneous penesaline seawater during syndiagenetic stage and the early stage of diagenesis are main factors controlling the reservoir diversity and reservoir rock types.

Based on the study of sequence stratigraphy, Feixianguan Formation is divided into two third-order sequences ( SQ1, SQ2) and eight system tracts, of which the lithofacies and paleogeography are analyzed. During the first deposition of the third-order sequence cycles ( SQ1), influenced by the regional tectonic uplifting in Changxing stage of Late Permian in northeastern Sichuan, the seawater once deep and wide became shallow, and the depositional evolution changed from basin facies to open-platform facies, of which oolite beach developed well. During the second deposition of the third-order sequence cycles ( SQ2), due to arid and hotter climate, fallen sea level, limited water cycle and exposed carbonate platform, the depositional evolution became to restricted platform and evaporated platform facies, and the oolite beach in northeastern Sichuan decreased. Finally, the sedimentary geomorphology was nearly full filled.

通过对四川盆地川中地区长兴组、飞仙关组沉积相、地震相研究，认为川中地区由于晚二叠世拉张坳陷的原因，在武胜、篷溪、盐亭一带形成了蓬溪&mdash;武胜台凹。蓬溪~武胜台凹南陡北缓，地震反射特征是在长内长顶形成平行-连续双强反射，在飞一段发育叠瓦状前积层。台凹内部上二叠统厚度薄，下三叠统飞仙关组厚度大，形成富泥的沉积补偿平衡型混积体系。蓬溪~武胜台凹控制了台内古地貌高带的形成与发育，也对生物礁滩的分布起到控制作用，台凹后缘遂宁断高带与前缘广安抬斜高带是寻找礁滩气藏的有利区带。

In this paper, both sedimentary and seismic facis of Changxing and Feixianguan formations, central Sichuan Basin, are studied. It is considered that, caused by tensional depression at later Permian, the Pengxi-Wusheng Depressional Platform formed along Wusheng-Pengxi-Yanting zone. The platform is characterized by steep in south and gentle in north, and its seismic reflection is of a parallel-continuous dual strong reflection formed at long-top within platform. In addition, some imbricate forest beds developed in T1f1. Within platform, the upper Permian is featured by thin thickness whereas lower Triassic Feixianguan Formation by thick thickness, and to form a mixed deposition of sedimentary compaction balanced type with rich mud. This platform controls not only the formation and development of paleogeomorphic highs but also the bioreef and shoal distribution. Studied results show that the favorable zones to discover both bioreef and shoal gas reservoirs are Suining fault high in back margin and Guang&rsquo;an uplift inclined high in front margin within platform.