Seismic data in the Yubei region has a relatively low signal-to-noise ratio, with multiple interbed multiples developed in the Ordovician strata, significantly affecting the accurate imaging of complex structures and reservoirs, leading to considerable uncertainty in structural interpretation and reservoir prediction. This paper first determines the styles of complex structural belts influenced by interbed multiples through wave equation forward modeling. The parallel-layered reflection at the top of complex structures is due to the alteration of effective strata reflection caused by strong interbed multiples at the top. Second, integrating data from drilling, logging, and geological aspects in the region, seismic wavefield characteristic forward modeling analyses for different types of reservoir are conducted. The results show that factors such as the scale and spatial development position of fractured-vuggy reservoirs have significant impacts on seismic reflection characteristics, strong reflective interfaces may mask the reflection characteristics of the top reservoir, the development of fractured-vuggy reservoirs at different positions can weaken or enhance the reflection of strata interfaces; locally intensive development of fractures in the Ordovician manifests as weak bead anomalies, while large-scale fracture reservoirs exhibit chaotic reflections, and karst caves are characterized by distinct moderately strong bead or tabular amplitude anomalies. By comparing with actual seismic data, the correctness of the complex structural interpretation model is effectively verified, and seismic wavefield characteristics of various types of Ordovician reservoir are summarized, providing a certain basis for understanding the interpretation of complex structures and the reflection characteristics of fractured-vuggy reservoirs in the region.

Objective To reveal the structures and evolutionary patterns of faults in the central and northern parts of Tazhong Uplift, Tarim Basin, Methods this paper systematically discusses the types of fault structures, geometric characteristics, differential activity mechanisms, and tectonic evolution processes in this area by analysing detailed structural interpretations and coherent slices of combined large 3D seismic data along with the regional dynamic background. Results The results show that there are 4 types and 7 evolution stages of faults in the central and northern parts of Tazhong Uplift, among which thrust faults and strike-slip faults are particularly common. On the plane, NW arc thrust faults intersect with NE-, NW- and NS-striking strike-slip faults; vertically, the fault stratification and differential activity characteristics are obvious. In the Lower Ordovician and the belowing layers, faults developed in large numbers and were mainly linear in their trending directions. As for the Middle Ordovician-Middle and Lower Devonian layers, faults are mostly in the echelon type. In the Upper Devonian-Permian layers, a few faults developed in the Tazhong Ⅱ fault zone and the southwestern end of the Shunbei 5 fault zone. Conclusion The fault activity in the study area was controlled by stress sites exhibiting diverse properties across multiple phases and directions and experienced an extremely complex evolutionary history: In the Early Caledonian period, a small number of normal faults, such as the Tazhong Ⅱ fault zone, were mainly active; in the Middle Caledonian Ⅰ period, the fault activity was very strong and was characterized by coevolution and mutual coupling of thrust faults and strike-slip faults. The strike-slip faults obviously cut or restricted the thrust faults. The fault activity of the Middle Caledonian Ⅲ period basically inherited the tectonic framework of the Middle Caledonian Ⅰ period, but the characteristics of transtensional fault activity in the Shunbei 4 and 5 fault zones are significant. From the Late Caledonian to Early Hercynian, some of the faults inherited activities with obvious transtensional characteristics. Conversely, in the Indochina-Yanshan period, only a few faults inherited activity, and the development area of transtensinal fault is further expanded to the south. During the Himalayan period, the tectonic movement of this area was relatively stable, and the complex fault structures that formed in the early stage transitioned into the deep burial stage.

在沙漠区勘探中,由于复杂近地表和巨大沙丘的影响,地震资料品质普遍较低,且由于地下强反射层的存在,目的层有效信号弱、多次波能量强,现有的层间多次波预测和压制方法很难奏效,特别是数据驱动的层间多次波压制方法对地震资料的品质要求更高.针对沙漠区地震资料特点,提出了一种以逆散射级数法为核心的多方法联合多次波压制新策略.该策略首先提高沙漠区地震资料信噪比,然后利用层位约束改进逆散射级数算法,组建形成一套以逆散射级数法为核心的具有针对性的多方法分类、分域、逐级多次波压制处理流程.西部某工区实际资料的测试结果表明,新策略不但能有效提高资料信噪比和分辨率,还能有效压制目的层多次波,保护有效波并改善断裂和储层成像质量,从而为综合解释和目标评价提供更可靠的资料保障.

The application of ant-tracking in seismic interpretation shows its advantages in fault characterization.However, this technology is limited by the quality of seismic data, the selection of ant-tracking input data, and multi-solution caused by single attribute.Thus, how to improve the accuracy of ant-tracking has been the hot issue and hard nut to crack in the industry.This paper takes well-block 1 in Shunbei area of Tarim Basin as the research object, and analyses the differences and application potential of chaos, variance, and the maximum positive curvature theories in fault detection.Besides, based on generalized S transform spectral decomposition, we compare discontinuity detection effects of chaos, variance and the maximum positive curvature attributes in different frequencies.Next, the data is processed after discontinuity detection with ant-tracking and optimize the best date for each frequency.Finally, RGB fusion is carried out after occurrence control.Results show that chaos in low frequency, variance in medium frequency and the maximum positive curvature in high frequency respond well with big, medium and small faults.The ant-tracking aided with multi-frequency domain and different fault detections can display multi-scale fracture distribution and enrich the underground geological information.

The No. 5 fault zone in Shunbei area, a main strike-slip fault zone running through two paleo-uplifts and being devided into north, middle, south and uplifted segments, has always been the focus of research on the formation and evolution of the strike-slip fault system in Shunbei area and its surroundings. In this study, the latest high-precision 3D seismic data newly acquired and processed are applied to carry out the fine analysis of the uplifted segment of the No. 5 fault zone in Shunbei area, determining its geometric and kinematic characteristics and revealing its formation and evolution process. According to the change of strike angle and segmented deformation pattern, the uplifted segment of the study area can be divided into three sections: the north translational section (NE16°) (uplifted segement Ⅰ), the middle pull-apart section (NE19°) (uplifted segment Ⅱ), and the south compressional-uplifted section (NE25°) (uplifted segment Ⅲ). The uplifted segment in the study area develops a layered deformation pattern composed of high and steep strike-slip faults and multiple suites of en echelon normal faults from bottom to top, while undergoing multistage strike-slip activities during the Middle Caledonian, Late Caledonian, Middle-to-Late Hercynian and Indosinian-Early Himalayan periods. In the study area, the strike-slip activities feature “strong in the segments Ⅱ and Ⅲ, weak in the segment I”. Under the influence of stress transmission from south to north, the south and uplifted segments present sinistral strike-slip from south to north with No. 1 fault zone in Tazhong area as the boundary at the initial stage of development, while the north and middle segments present dextral strike-slip from north to south, with the maximum principal stress deflecting from NW to NE. After the Late Caledonian period, the No. 5 fault zone in Shunbei area presented sinistral strike-slip as a whole, while during the Indosinian-Early Himalayan periods, the uplifted segment reversed to dextral strike-slip, with the maximum principal stress reversing from NW to NE.

塔里木盆地巴麦地区的地震资料受复杂地震地质条件的影响,层间多次波广泛发育,识别和压制难度大,导致奥陶系碳酸盐岩断控缝洞型储层成像不准确,制约了该地区油气勘探部署.通过模型正演及邻区VSP波组特征标定分析,明确了层间多次波产生的必要条件、发育特征及对有效反射信号的影响,并有效识别出二叠系火成岩巴楚组标准灰岩、二叠系不整合面小海子组灰岩等多套产生层间多次波的"源镜"组合,形成了"两步法"层间多次波叠后压制技术:首先利用多次波分布规律,采用匹配追踪法压制层间多次波;然后基于剖面频率特征,利用优势频率信息提取技术,压制高频层间多次波并增强资料信噪比.研究区实际资料处理结果表明,该方法能够有效压制奥陶系内幕层间多次波,提升目的层断控碳酸盐岩缝洞型储层成像质量.

针对在调谐背景下直接利用叠后属性识别预测薄层砂体多解性强的问题,研究并提出了塔中北坡S1井区目标储层基于部分叠加角道集属性的含油薄层砂体预测方法.首先,以现有井资料为基础,开展薄层地震反射波随入射角变化规律的正演分析,认为研究区含油薄层反射的视AVA效应是敏感且可检测的;其次,在对原始CRP道集资料提高储层成像精度预处理的基础上,利用部分道集叠加的方式进一步增强薄层反射视AVA效应的规律性;然后,结合正演模拟取得的认识和实钻井目的层油气显示结果,进行基于部分叠加角道集数据的属性随入射角变化规律分析,认为在调谐背景下目的层最大波峰振幅和最大波峰主频属性是检测薄层砂体含流体性质的敏感地震属性,据此提出了相应的油气检测因子,预测了研究区目的层含油薄层砂岩有利分布区.

The Hierarchy of stratigraphy unconformities and sequence interfaces in different tectonic parts has played an important role in distribution of reservoirs of carbonate rocks.An integrated study of Caledonian unconformities(seismic reflection of stratigraphic surfaces of T27 and T47),structure patterns of margin and platform in the Late Ordovician,depositional sequence and statistic data of reservoirs developed in 32 wells,as well as carbon and oxygen and strontium isotope for calcites filled in fractures-vugs and the Ordovician carbonate rocks in 11 wells,in the Western Tazhong is reported.The results show that the first episode of the Middle and Late Caledonian is of the characteristic of transformation from tectonic extensional to compressional loading,and the stratigraphy unconformities of T47 is composed of top-truncation and erosion developed from the margin into intra-platform as well as a strong karstification,and later attributed to deepened submerge sequence(drowned) with filling-up;while the stratigraphy unconformities of T27 would be defined as overlying deepened submerge sequence and above possibly forming of condense section,and erosion and subaerial-karstification seemed to occur in high-position area.The aggradation would be gradually replaced by progradation in the Upper Ordovician margin toward the interior platform,associated with the highstand systems tract(HST) predominantly and the transgressive systems tract(TST) secondary;while distribution of larger slope angle of the Upper and Middle Ordovician would have significantly contributed to a greater remanent strata of Lialitaga and Yijianfang Group.The stack patterns of 3th or above parasequence or cycles in the Ordovician are much similar to each other in the Western Tazhong,the similar average value of δ18O and δ13C,87Sr/86Sr for either Ordovician carbonate rocks and calcites or dolomites in vugs and fractures suggested the latter intimately inherited from or associated with that of the pervious matrix rocks;the significantly depleted δ13C PDB and δ18O PDB in calcareous dolostone and dolostone and calcites or dolomites in vugs and fractures in Yingshan group of the Middle and Lower Ordovician may respond to the degree of erosion of strata or karstification developed in different tectonic belts;unlike lower 87Sr/86Sr in rocks or calcites in vugs and fractures of Lialitaga and Yijianfang Group,the rather higher contents of 87Sr/86Sr in Yingshan Group is composed of terrestrial strontium and the dissolved strontium with a rather higher terrestrial-derived strontium,indicating the different sedimentary environment and widespread development of karstification for Yingshan group.The reservoirs of Yingshan formation of the Middle and Lower Ordovician,in great extent,depended on the development of karstification that was closely associated with fault-related folding uplift,denudation and subaerial-unconformity development(T47).In the areas of inherited developed structures,topographic rising and the hanging wall of thrusting-faults,the forming of reservoirs of carbonate rocks would be defined as "residues of phreatic zone",which was formed by a series of continued geological stages,i.e.,uplift linked to tectonic compressional loading,development and partly erosion of freshwater phreatic zone,and overlapping of multi-episode karstification;whereas "un-differentiated freshwater phreatic and leaching zone" likely occurred either in the weak transformation parts or in the gentle topographic slope or in the footwall.

Time-frequency analysis using Wigner-Ville distribution suffers from interference of the cross terms.We presented a new Wigner-Ville distribution based on empirical mode decomposition (EMD).Nonstationary signal is decomposed into intrinsic mode functions (IMF)which are stationary,and Wigner-Ville distributions are then computed on these IMFs.Tests on synthetic and real seismic data showed the effectiveness of the proposed method.

The structures of mountain front in southern Junggar basin are complex and the variation of lateral velocity in deep formation is considerable.In order to improve the accuracy of structure map- ping,varying velocity mapping technique was used to map the structures.Firstly,the T_0 layer data of post-stack time migration domain(abbreviated in migration domain)was de-migrated into common-depth-point-stacking time domain(abbreviated in stacking domain).Then,stacking velocity inversion method was used to obtain the horizontal velocity responding to the grid points of T_0 layer data in stacking domain;finally,3-D ray map-tracing migra- tion method was applied to convert T_0 map into depth map.The varying velocity mapping result was compared to simple time-depth relationship transformation result,showing that the varying veloci ty mapping technique can effectively improve the accuracy of struc- ture maps and an anticlinal trap was discovered in the south of the working area.

Due to the traditional methods of seismic inversion can't effectively predict and describe the characteristic of the complex reservoirs,by using the low-frequency of acoustic log and the high frequency of log curve which can reflect the characteristic of reservoir,the pseudo-acoustic curve which can exactly reflect the characteristic of reservoir was reconstructed,and then the acoustic curve was gave way to the pseudo-acoustic curve for inversion.The result of inversion showed that the method could enhance the reservoirs' character,greatly improved interpretability of inversion result and solved the geological problem of description of thin reservoirs.The pseudo-acoustic curve was used to inversion of seismic data in Sanshun and Kongquehe area of the Tarim Basin.And the results showed the local characteristic of reservoirs,directly guided hydrocarbon exploration in the area.