Research on the sedimentary facies of the Middle Permian Maokou Formation in the Sichuan Basin has predominantly concentrated on inner-platform settings, with the evolution of its platform-margin facies belts being less well understood. This study, utilizing integrated well-log, core and seismic data from the Jiange-Yuanba area, employs sequence stratigraphy, sedimentology and seismic geomorphology to delineate sequence architecture, interpret depositional environments and characterize platform-margin development. Key findings include: (1) The Maokou Formation comprises three third-order sequences (SQ1–SQ3); SQ1 features subdued palaeotopography, whereas SQ2–SQ3 exhibit pronounced south-thick/north-thin differential subsidence. (2) Deposition evolved from an early gentle carbonate ramp to a progradational, rimmed carbonate platform during its middle–late stages. (3) Whereas SQ1 contains sporadic, low-energy shoals on subtle palaeo-highs, SQ2–SQ3 developed NW–SE-trending, vertically stacked platform-margin shoal complexes. These shoals constitute potential large-scale, high-quality reservoirs and represent key exploration targets. This work refines the sedimentary model for the northwestern Sichuan Basin and provides insights for hydrocarbon exploration in the Maokou Formation.

The evolutionary history of the Deyang–Anyue depression (DAD) during the Sinian and Cambrian periods in the Sichuan Basin (SB) remains unclear, and the lithofacies palaeogeography during key stages is poorly understood. To address these gaps, this study integrates data from core samples, thin sections, well logs, seismic records, and previous research. The analysis focuses on the tectonic–sedimentary background shaped by the evolution of the DAD in the SB. Using 2D and 3D continuous seismic data, the study reconstructs the evolutionary process of the DAD, reconstructs lithofacies palaeogeography for critical periods, analyses the temporal and spatial distribution patterns of reservoir variations within the context of DAD evolution, and identifies the reservoir development zones of the Dengying Formation (DY). The research reveals that the inherited geomorphic pattern of the DY during its depositional and karst exposure stages—characterized by lower elevations in the west and north and higher elevations in the east and south—controlled the deposition and filling patterns of the DY across different periods. Consequently, the formation is thicker in the west and north and thinner in the east and south. The scale and morphology of the DAD were shaped by the combined effects of negative geomorphology, regional extensional forces, and sea-level fluctuations prior to DY deposition. The DAD underwent four major evolutionary stages: initial embryonic formation, progressive development, structural stabilization, and eventual infill and demise. Controlled by the tectonic and sedimentary evolution of the DAD, the DY platform evolved from a ramp platform depositional system to a rimmed-platform depositional system. Constrained by seismic facies, the mound–shoal complexes of each stage display a sequential evolutionary pattern, characterized by both inherited construction and a consistent ring-shaped distribution around structural highs. The DAD governs the differential reservoir-forming processes of the DY and the development of high-quality source rocks. The Intraplatform karst-reworked slope reservoir zone of the fourth member of the Dengying Formation (D4) represents a key future exploration target, owing to its favorable reservoir development potential and excellent hydrocarbon source configuration.

Accurate seismic characterization of deep carbonate reservoirs is hindered by low-frequency data and complex overburden that create non-unique attribute responses. To reduce this ambiguity, we propose a lithofacies-association zonation workflow that couples forward-modeled petrophysical constraints with multi-attribute fusion. The workflow partitions the survey into zones of comparable overburden geology, performs zone-specific attribute optimization, and validates predictions against blind wells. Application to the Cambrian Longwangmiao Formation in the Northwestern Moxi area, Sichuan Basin, shows that the conventional “bright-spot” model fails where overburden lithology changes rapidly. Prior to zonation, the coefficient of determination (R²) between predicted and measured reservoir thickness is only 0.04, indicating negligible correlation. After zonation and weighted attribute fusion, R² improves from 0.04 to 0.56–0.69 depending on the zone, demonstrating the effectiveness of the proposed approach. The resulting map correctly identifies thicker reservoirs in the Gaotai-Formation residual zone, consistent with bedding-parallel karstification predicted by the geological model. The workflow is reproducible for similar karst-modified carbonate platform with lateral overburden variability.

While seismic geomorphology has revolutionized reservoir characterization in shallow clastic systems, its application to ultra-deep carbonate environments (> 6000 m burial depth) remains highly controversial. Conventional seismic attribute analysis often generates misleading “funny-looking things” and interpretational traps in low-frequency, high-velocity settings, challenging its reliability. This study seeks to determine how robust seismic geomorphological interpretation can be obtained in ultra-deep carbonate settings where conventional attribute analysis proves ineffective. Utilizing 3D seismic data (dominant frequency 20 Hz), wireline logs, and core samples from the Cambrian Longwangmiao Formation (4800–7000 m depth) in the central Sichuan Basin, we reconstruct pre- and post-depositional geomorphology. Results reveal dramatic topographical inversion, shifting from high-standing to low-lying terrain toward the southern region and from low-lying to high-standing toward the northern region, both before and after the Longwangmiao Formation deposition. It is interpreted as an early response to the Caledonian Yunan movement transitioning from extension to compression. While confirming that attribute analysis is unreliable in these challenging ultra-deep environments, we demonstrate that isopach and cast methods successfully delineate geomorphic controls on circular shoal distribution. Consequently, the Shehong–Santai–Pengxi shoal zone is identified as the next high-potential target following Moxi, thereby establishing a robust workflow for seismic geomorphology in similar deep-buried carbonate systems globally.

The Changxing Formation of the Upper Permian in the Sichuan Basin remains a focal area for natural gas exploration. Previous research on this formation has predominantly focused on platform-margin reefs in northeastern Sichuan Basin, while reservoirs within the platform have received limited attention. This study addresses this gap by systematically analyzing bioclastic shoal reservoirs in the Zhongjiang-Moxi region of central Sichuan Basin, using integrated methods including core observations, petrographic analysis, well log interpretation, and 3D seismic data. Results reveal that the study area primarily hosts porous bioclastic limestone reservoirs, characterized by storage spaces dominated by intragranular and interparticle dissolution pores. These reservoirs exhibit distinct facies-controlled attributes. Key controlling factors include: (1) syn- to penecontemporaneous karstification, (2) sea-level fluctuations governing reservoir thickness and stacking patterns, (3) micro-paleogeomorphic variations influencing early exposure dissolution, and (4) dolomitization enhancing reservoir quality. Based on these findings, two depositional evolution models for intraplatform reservoirs of the Changxing Formation are proposed.

近年来,川中地区多口井在栖霞组钻获高产工业气流,展现出该层系巨大的勘探潜力,但较之川西北台缘带,位于台内的龙女寺地区栖霞组碳酸盐岩滩体规模小,储层厚度薄,远低于地震纵向分辨率,一直未取得较好的储层预测效果,严重制约着广大台内地区的油气勘探开发.为此,针对台内地区薄储层预测难点,综合利用岩芯、薄片、测井及地震等资料,以地质-地球物理紧密结合的思路,对川中龙女寺地区栖霞组储层控制因素及预测地质模型进行研究,研究结果表明,该区域栖霞组储层主要为滩相白云岩储层,储集岩以晶粒云岩、云质灰岩为主,主要储集空间为晶间(溶)孔、溶洞,可见少量裂缝.控制栖霞组相对优质储层形成的主要因素为栖霞期古地貌位置、沉积微相及断裂发育情况,据此建立了"栖霞期古地貌高地+滩核和滩缘微相区+断裂发育区"的龙女寺栖霞组薄储层预测地质模型,并在此基础之上优选出储层发育有利区,为栖霞组台内地区油气勘探部署优选有利区带提供理论支撑.

基于岩心、薄片、测井及地震资料的综合分析,围绕川中北斜坡地区寒武系沧浪铺组一段颗粒滩特征及分布规律开展研究,认为:1)区内滩体岩性以鲕粒灰岩及在此基础上受不同程度白云石化作用改造的残余鲕粒云岩、云质鲕粒灰岩、灰质鲕粒云岩为主;颗粒滩在自然伽马曲线上以箱形、漏斗形响应为主,地震反射上以丘状杂乱、中弱振幅、中低频的a类地震相响应最优,b类地震相次之.2)纵向上,沧一段颗粒滩单体厚度不大,表现为多套频繁叠置、累计厚度具有一定规模的特征;横向上,滩体连续性较好,可对比追踪;平面上,三维地震资料精细刻画显示滩体北西—南东向展布,呈现整体连片、局部分异的特征.3)滩体发育受到海平面及古地貌的双重控制,位于研究区东侧的相对古地貌高带及裂陷槽边缘地带是沧浪铺组颗粒滩发育的主要区域,也是下一步勘探工作的主要方向.

Based on data from cores, cuttings, thin sections, and logging and seismic activities, the lithofacies, geophysical response, and spatial distribution characteristics of the Permian igneous rocks in the northern part of central Sichuan were analyzed and summarized. Furthermore, the eruption and filling processes of the igneous rocks were restored, and the hydrocarbon geologic significance of the volcanic eruption events was investigated. The results reveal that the igneous rocks in this area are volcanic overflow facies and sedimentary facies, with volcanic lava and pyroclastic rocks developed. Only one eruption cycle occurred vertically. The igneous rocks exhibit low natural gamma ray, low acoustic, high compensation neutron logging, high density, and high resistivity logging values. The seismic responses are characterized by multiaxial, flexural, and upward arching. The plane distribution shape is an inverted U, with a nearly east–west linear distribution. The igneous rocks in the area were emplaced via a fissure eruption along the basement faults in the early Longtan. The eruption-filling process can be roughly divided into four stages: the deposition of the Maokou Formation, the geomorphological embryonic stage, the geomorphological differentiation stage, and the volcanic eruption and filling stage. The underdevelopment of primary pores and the lack of dissolution in the later stage led to poor igneous reservoir performance, which limits the igneous reservoir hydrocarbon exploration prospect. However, the early faulting activity resulted in the differentiation of the Maokou Formation sedimentary and karst landforms. The thermodynamic conditions created by the later eruption of the igneous rocks, sufficient Mg 2+ sources, and favorable geomorphological units laid a good foundation for the development of the dolomite reservoirs in the Maokou Formation. Among them, the karst slopes and highland areas of the Maokou Formation along the two sides of the strip of igneous rocks are dominant areas for the development of the dolomite reservoirs in the Maokou Formation.

In view of the unclear understanding of the development and distribution characteristics of the intra-platform shoal of the Changxing formation in the southern Sichuan Basin, analysis and summary of the petrological characteristics and sedimentary cycle characteristics of the intra-platform shoal in the Changxing formation in the Gaoshiti area were conducted. In this study, the idea of seismic sedimentology is adopted, the top geomorphology and the root mean square (RMS) amplitude attributes of the Changxing formation were used as constraints, combined with the granular rock thickness/stratum thickness (G/S) of wells to depict the planar distribution characteristics of the intra-platform shoal in the study area. Through the research and analysis, it is concluded that the Changxing formation in the Gaoshiti area has a geomorphological pattern of ‘three uplifts and two depressions’ at the end of the deposition. The geomorphological differentiation characteristics are highly consistent with the variation law of the RMS amplitude in the plane, and there is a good correlation between the two and the G/S of the strata. Thus, three belts of intra-platform shoals with NW–SE distribution are identified in the study area.

Based on comprehensive analysis of cores, thin sections, logging and seismic data, the sequence stratigraphy and sedimentary evolution of the third and fourth members of Sinian Dengying Formation (Deng 3 and Deng 4 members for short) in the Gaomo area of Sichuan Basin were investigated, and the favorable zones for reservoir development in the Deng 3 Member and Deng 4 Member were predicted. (1) Two Type I and one Type II sequence boundaries are identified in the Deng 3 and Deng 4 members. Based on the identified sequence boundaries, the Deng 3 and Deng 4 members can be divided into two third order sequences SQ3 and SQ4, which are well-developed, isochronal and traceable in this area; the SQ3 thins from west to the east, and the SQ4 thins from northwest to southeast. (2) The sedimentary environment from the depositional period of SQ3 to SQ4 has experienced the evolution from mixed platform to rimmed platform, and the platform rimmed system on the west side is characterized by the development of platform margin microbial mound and grain shoal assemblages. The intraplatform area is a restricted platform facies composed of a variety of dolomites, and there are local micro-geomorphic highlands of different scales and scattered intraplatform mounds and shoals. (3) The Deng 4 Member reservoirs, with obvious facies-controlled characteristic, are mainly distributed in the upper part of high-frequency upward shallow cycle and the high-stand systems tract of the third-order sequence vertically, and are more developed in the platform margin belt than in the intraplatform belt, and more developed in the Gaoshiti platform margin belt than in the west Suining platform margin belt on the plane. (4) Three types of favorable reservoir zones of Deng 4 Member have been finely delineated with 3D seismic data; among them, the mound and shoal facies zones developed in the ancient highlands of the intraplatform are the first choice for the next exploration and development of the Deng 4 Member.

Seismic data are an integrated reflection of the sedimentary interfaces and processes of paleo formations. In this study, seismic geomorphology was applied to analyze and reconstruct the paleogeomorphology of the sedimentation of the Cambrian Longwangmiao Formation in the central Sichuan area by combining three-dimensional (3D) seismic data, a large amount of drilling data, logging data, cores and thin sections. It is believed that the thickness of the Cang-2 member reflects the paleogeomorphology during the sedimentation of the Longwangmiao Formation. Forward seismic modeling was used to select the seismic physical attributes sensitive to the Cang-2 member, which were then used to reconstruct the paleogeomorphology during the sedimentation of the Longwangmiao Formation. The results of this study show that the larger the amplitude of the bottom trough of the Longwangmiao Formation, the higher the landform during the sedimentation period. Therefore, the Caledonian paleo-uplift had already taken shape before the sedimentation of the Longwangmiao Formation, creating a paleo-geomorphologic pattern containing two uplifts and one depression. The geomorphologic distribution controlled the development of the shoals and reservoirs. The geomorphic highlands not only contained shoals with large areas and thicknesses but were also susceptible to superimposed syngenetic and quasi-syngenetic exposures, which provided preferential flow channels for atmospheric fresh water in the later period and caused the reservoirs to be subjected to more intense karstification. Due to the differences in the potential energy of the topography, the quality of the reservoirs in the NW slope zone is the best, followed by that in the NW high zone and the SE sub-high zone, while the shoals and reservoirs of the sedimentary geomorphic lowlands are poorly developed.

2005年威远构造威寒1井龙王庙组获11×104 m3/d的测试产量揭示了四川盆地内部龙王庙组勘探的突破.随着勘探的深入,川中磨溪—高石梯地区多口百万立方米气井的获得证实了龙王庙组巨大的勘探潜力.然而,龙女寺构造龙王庙组储层发育情况展现出与磨溪—高石梯(高磨主体)地区较大的差异,以传统"亮点"反射模式作为储层预测的指导思想已经无法满足现今勘探的需要.以龙女寺构造龙王庙组储层为例,借助已有岩心、薄片、测录井及地震资料,对区内龙王庙组储层与高磨主体地区龙王庙组储层进行对比研究,同时对储层的地震响应进行进一步的探索.研究表明:研究区龙王庙组发育局限台地沉积,颗粒滩相作为储层发育的最有利相带,最主要的储集岩类为颗粒云岩及晶粒云岩,储集空间包括粒间(溶)孔、晶间(溶)孔、溶洞等;研究区内储层表现出低孔低渗的特征,非均质性强,纵向展布差异大,横向可对比性差.对比分析"亮点"反射模式,采用波形聚类属性对储层进行平面分布预测,明确不同储层发育情况对应的波形特征.Ⅰ类波形对应于储层发育于顶部,储层厚度＞30 m;Ⅱ类波形对应于储层发育于中部,储层厚度＞20 m,或顶部中部发育2套相距20 m左右、厚度15 m左右的储层;Ⅰ、Ⅱ类波形为储层发育有利波形;Ⅲ类波形对应储层较薄(＜5m)且储层呈薄互层状发育或储层欠发育;Ⅳ类波形对应储层欠发育;Ⅲ、Ⅳ类波形为储层发育不利波形.该方法可有效地规避"假亮点"反射,预测结果与沉积相发育特征及实钻井储层发育情况吻合率高.

As a typical kind of lithologic reservoirs, reef reservoirs are generally featured by their large single-well reservoir thickness, good reservoir physical properties, and high gas well productivity. The Upper Permian Changxing Formation is an important natural gas exploration target in the Sichuan Basin, which hosts a large reef gas reservoir and is mainly distributed along the Kaijiang-Liangping Trough. Comprehensive analyses are implemented to investigate reservoir characteristics and identify controlling factors of reef reservoirs in Changxing Formation in the Eastern Longgang Area, Northeastern Sichuan Basin, including core, logging, and seismic data analyses. Changxing Formation reservoirs in the study area mainly occur in the reef-shoal complex, which are featured by wide distribution, large thickness and generally good physical properties. Reservoir rocks are dominantly composed of bioclastic dolomite and silty-fine dolomite (with grain phantom structure), while the main reservoir space consists of residual intergranular pores, intergranular dissolution pores, and karst vugs. In the seismic profiles, typical mound-shaped chaotic reflections can be clearly seen. It is suggested by the main reservoir development controlling factor analysis that the distributions of reef reservoirs are typically controlled by sedimentary facies belts, while the scale of the reef-shoal complex is determined by the pene-sedimentary micro-paleo-geomorphology. Dolomitization can not only significantly preserve the primary pores but also enhance the permeability of rocks. Moreover, karstification is the key to high-quality reef-shoal reservoirs.

为了得到低比转速离心泵叶轮内的应力和变形规律,找到最大应力点和最大变形位置,在ANSYS中对叶轮所受的离心力、流道介质压力、圆盘摩擦力、前后盖板压力及其耦合作用的情况进行受力变形分析;结果证明前后盖板的受力变形完全不同;介质压力作用下叶轮产生的应力和变形最大,最大应力出现在叶轮出口叶片与前后盖板的交界处,属于应力集中点;圆盘摩擦力较其他载荷对叶轮受力变形产生的影响较小;以上研究结果有助于预测叶轮的变形规律,对叶轮的形状设计具有重要意义.

To analyze the impeller-guide vane interaction and the property of pressure fluctuation in the centrifugal pump,the three-dimensional unsteady Navier-Stokes equation and the standard κ-ε turbulence equation were solved applying the sliding mesh technology on the basis of the Fluent software.A multi-operating unsteady numerical simulation of the internal flow field was conducted.The performance curve of the pump was calculated.The internal pressure,velocity distribution,pressure fluctuation time domains and spectral properties in different flowrates were also obtained.The calculation shows that due to the resistance and interference of the guide blade head toward the impeller outflow,the vortex of local fluids arises.The pressure fluctuation in the pump in various operating conditions agrees with the law of remarkable periodical change.The pressure fluctuation at the dynamic-static coupling position between impeller and guide vane is mainly subject to blade frequency.Blade frequency is the main frequency of pressure fluctuation in flow channel.The main frequencies remain the same in different flowrates but the amplitude of the main frequency is slightly different.The dynamic-static coupling between rotating impeller and static guide vane is the main source for pressure fluctuation.

采用超声导波无损检测技术对油管进行无损检测时,用于激励导波的脉冲正弦波信号具有激励电压、激励频率、偏置磁场强度及脉冲周期数等重要参数,为了找出最佳激励参数,提出了确定最佳激励参数的试验方法,并在油管中使用该方法开展了试验研究。通过试验得出了适用于J55材质油管的最佳激励参数:激励频率50kHz,激励电压4V,脉冲包含的周期数6,偏置磁场强度0.023T。采用最佳激励参数对油管中的穿孔缺陷进行了检测,结果表明,检测系统可以清晰地分辨出缺陷信号,证明了最佳激励参数的可靠性。

The principle and advantage of guided wave testing technology were introduced.Some analysis for parameters of incentive source has made,which was used in pipeline guided wave detector.On the basis of direct digital frequency synthesizer(DDS),it focused on the use of DDS chip AD9850,microcontroller and high performance operational amplifier to design an incentive source for guided wave detector.Result showed that the design completely met the requirements,and had excellent frequency and phase output.It could be used for high accurate incentive source in practice.