【作者】 刘振东；

【导师】 顾汉明；

【作者基本信息】 中国地质大学 ， 地球探测与信息技术， 2010， 博士

【摘要】 王集—新庄地区位于泌阳凹陷北部斜坡的中东部的王集—新庄鼻状构造带上,具有良好的构造背景,是油气运移的有利指向区。该区主要发育一系列北东向断层和少量北西向断层,断层的相互交切并与构造背景配置形成了一系列断鼻、断块,为油气的聚集提供良好的圈闭条件。北东方向的候庄三角洲砂体和北西方向的王集三角洲砂体在该区广泛分布,具有良好的储层条件,总体来说该区是形成油气聚集的有利场所。目前,在该区已取得了较大发现,探明石油地质储量近4000万吨,主要分布在核三上段,核三下段,目前所发现的储量比例较小,并且主要分布在王集西部地区,在王集东部和新庄地区基本没发现核三下段地质储量。综合分析研究认为,该区核三下段的成藏条件与核三上段类似,部分井在核三下段也发现了不同级别的油气显示,还有个别井见到了工业油流,认为核三下段也是形成油气聚集的有利场所,且核三下段分布面积广,在斜坡地带核三上段大部分被剥蚀的地区,核三下段仍有较好保存。但是,王集-新庄地区目前的地震资料仅能满足浅层勘探的需要,由于中深层该区地震资料品质较差,难以满足进一步勘探的需要。由于受当时技术条件限制,且以前三维地震勘探以核三上地震勘探目的层,已有的地震资料从核三段Ⅲ砂组以下地震反射同相轴连续性变差,信噪比低,反射品质较差。受地表地震地质条件和深部地震地质条件横向不均匀性的影响,造成了资料品质的横向不均匀性。小断块群成像不清,横向和垂向分辨率较低,层位追踪及一些小断层的解释仍有一定的模糊性、多解性,很难对核三下段构造特征进行准确、精细的描述。因此,针对王集-新庄地区部署了重新采集任务,针对泌阳凹陷核三下段地震反射信号弱、信噪比和分辨率低的问题,开展技术攻关,提高中深层地震资料的信噪比、连续性和对比精度,提高小断块群成像精度,搞清复杂断块群的构造断裂特征。本文针对复杂断裂带地震反射信号弱、信噪比和分辨率低的问题,基于复杂断裂带的地震地质特点,开展高精度地震采集,采用基于波动方程正演模拟和照明分析技术进行野外观测系统的设计和优化,达到对复杂断裂带地下地质目标的最佳观测,最大限度获取完整丰富的波场信息。在处理过程中,充分利用高精度采集的优势,开展等效模型层析静校正方法研究,精确计算近地表模型和静校正量,提高分辨率和小断层成像精度；采用正演与共轭反演算子叠前深度偏移算法和速度分析方法,使断层准确归位,提高复杂断裂带的成像精度,获得准确的构造信息和储层信息。形成了一套适应复杂断裂带油藏勘探的采集和处理方法,为合理落实复杂断裂带的构造面貌,提高钻探效果提供技术支撑。本文的主要工作及结论如下：(1)本研究利用高精度的交错网格高阶有限差分方法,利用双程波方程模拟了泌阳凹陷复杂断裂带模型中地震波的传播,进而对王集断鼻构造带的多级断裂构造进行了地震波照明分析,实现野外观测系统的设计和优化。确定最佳分辨率面元的大小、地面最佳采集位置、最大最小炮检距、排列长度、排列滚动等,直观显示能量在地下介质中的分布情况,分析地震波传播规律和地层能量响应,达到对复杂断裂带地下地质目标的最佳观测,最大限度获取完整丰富的波场信息。在有效目的层范围内本次地震采集的观测系统在偏移距和方位角的分布上基本接近于高精度宽方位采集,可对地下进行全方位照明,既有利于浅层不整合面的完整显现和追踪,也有利于复杂断裂的成像,有利于提高地震资料的信噪比,满足构造解释和岩性勘探需要。(2)根据模型照明分析技术,综合判断后采纳了方案1。在南部采用24L8S136R204F观测系统,北部采用24L8S144R108F观测系统,能保证220m以下的目的层信噪比,并且炮密度小成本较低,炮检距集中度较好,施工组织方便。根据方案1的偏移距分布显示,近偏移距和远偏移距覆盖都比较均匀,,200米以内偏移距基本全部覆盖。近偏移距的均匀分布保证了剖面无缺口,有利于超浅层及不整合面成像。(3)在泌阳凹复杂陷断裂带,层析静校正比折射静校正和高程静校正有更好的效果。它可使弯曲和连续性差的同相轴形态变得更加自然顺畅,信噪比增高,层析静校正后浅部同相轴细节丰富,频率增高,说明达到了同相叠加的效果。(4)引入了正演与共轭反演算子,实现了炮域波动方程延拓法叠前深偏移。该算法稳定,适用于复杂速度场,并且计算精度高。在泌阳凹陷复杂断裂带开展提高炮域波动方程延拓法叠前深度偏移的成像精度和计算效率的方法研究。偏移结果信号保真度较好,地震反射层特征明显,各个主要层段波组特征清楚,地质现象丰富,利于地层追踪对比,小断层断面成像清楚,断点清晰,偏移归位合理,断裂系统成像得到明显改善,构造形态改善明显,同相轴自然,信噪比和连续性都得到提高。(5)在浮动基准面处理和精细选择切除函数,有效利用高精度采集的资料,保留浅层有效反射信息,浅层不整合面保留清楚；(6)处理结果分辨率得到有效提高。资料频带较宽,有效反射信号频带基本分布在5～100Hz,核二和核三上段(剖面500ms以上)主频达到45-50Hz,核三下段(剖面700ms～1700ms)主频达到30～40Hz。基底成像准确,形态清楚,有利于区域构造研究、沉积演化研究和应力分析。本论文创新点如下：(1)引入了正演与共轭反演算子,实现了炮域波动方程延拓法叠前深偏移。该算法稳定,适用于复杂速度场,并且计算精度高。在泌阳凹陷复杂断裂带开展提高炮域波动方程延拓法叠前深度偏移的成像精度和计算效率的方法研究。偏移结果信号保真度较好,地震反射层特征明显,各个主要层段波组特征清楚,地质现象丰富,利于地层追踪对比,小断层断面成像清楚,断点清晰,偏移归位合理,断裂系统成像得到明显改善,构造形态改善明显,同相轴自然,信噪比和连续性都得到提高。(2)首次将波动方程正演和照明技术应用于泌阳凹陷复杂断裂带观测系统设计,并取得了较好的应用效果。波动方程正演和照明技术解决了泌阳凹陷复杂断裂带数据采集要求的高精度、宽方位、偏移距均匀、覆盖次数均匀等问题,实现了对地下地质目标的均匀和全息观测。更多还原

【Abstract】 Wangji-Xinzhuang area, located in the Wangji-Xinzhuang nose structure zone, which is in the central and eastern part of the northern slopes of the Biyang Depression, has a good tectonic setting, and is a favorable directional zone of hydrocarbon migration. The area mainly consists of a series of NE-trending faults and a small amount of NW-trending faults. Configuration of intersection faults and tectonic setting lead to the formation of a series of fault blocks and faulted noses, providing trap conditions for accumulation of oil and gas. The sandstone body of Houzhuang delta in the northeast area and of Wangji delta in the northwest area is distribute widely in this area. So the area is favorable for the formation of oil and gas accumulation.Currently, a great discovery has been made in this area that proven oil reserves here is nearly 40 million tons, which mainly distribute in upper member of Eh3. While small proportion of reservoir has been found in underpart member of Eh3, which mainly distribute in western area of Wangji, and none of the geologic reserve in underpart member of Eh3 was found in eastern Wangji and Xinzhuang area. Comprehensive analysis results indicate that reservoir forming condition in upper member of Eh3 is similar to that in underpart member of Eh3. In some wells have been displayed different level evidences of oil and gas in underpart member of Eh3, with a few wells obtaining commercial oil. Underpart member of Eh3 is regarded as the favorable place for hydrocarbon migration and accumulation. The underpart member of Eh3 distribute widely, which was still preserved well after large-scale erosions in upper member of Eh3.However, the current seismic data in Wangji-Xinzhuang region is only able to meet the needs of the shallow seismic exploration and it is difficult to meet the needs of future exploration because of the poor seismic data quality. Due to technological constraints at that time, and in the previous seismic three-dimensional exploration, the upper member of the Eh3 being the exploration target, the existing seismic data from the formation below the member H3 III Sand shows the worse continuity of seismic reflection, low SNR, and poor quality reflection. The imaging of small fault blocks is unclear with low lateral resolution and vertical resolution. Horizon tracking and interpretation of small faults is going with a certain degree of ambiguity and multi-resolution. It is difficult to describe exactly and accurately about the structure of underpart member of Eh3.Therefore, for Wangji-Xinzhuang region, there is a deployment of new acquisition task. Be aimed at the problems such as weak earthquake reflection, low SNR and low-resolution of underpart member of Eh3 in Biyang depression, it is necessary to strive to make technological breakthrough to increase the SNR, continuity and Comparison of accuracy of the seismic data in underpart member of Eh3 in Biyang depression, so as to increase the imaging precision of small fault blocks and beating out the fracture feature of the structure of the small fault blocks.This topic launched a feasibility studies about technical design in acquisition area, we analyzed the main technology and construction difficulty in the survey areas, and systematically analyzed the previous information according to geological tasks and technical requirements. In the base of Reconnaissance of the work area, data collection and analysis of the original three-dimensional data, we proposed feasibility studies and geometry design. Based on fine structure analysis, fault isolation and recognition of translocation system, the pre-stack migration is applied to the high-precision 3D seismic data in this area. Preserving shallow unconformable surface as possible, we increased the SNR of the seismic data and imaging precision of the complex fault, to provide accurate information for structural and lithology interpretation.The main contribution and conclusion are as follows:(1)High precession staggering grid high-order finite-difference algorithm was used in this research. Seismic wave propagation of complex fault belt in Biyang Depression was simulated with two-way wave equation. Then, seismic illumination analysis of multilevel tectonic system of Wangji fault nose structure was complicated, and the geometry system was designed and optimized. The bin size with optimum resolution, the best acquisition position, the maximum and minimum offsets, the arrangement length, and the arrangement rolling are all determined. Thus, it is possible to show the energy distribution in the underground medium, analyze the wave propagating pattern and stratum energy responds, and optimally observe the geological target in complex fault belt, in order to obtain the wave field information as complete and abundant as possible. In the effective range of target strata, this acquisition observation system was similar to high-density with wide-azimuth acquisition in terms of distribution of the offset and the azimuth. Therefore, it is possible to illuminate the underground medium omnidirectionally. In another word, it is favorable to not only the tracing of the shallow layers, but also the imagination of complex fault. Thus, signal to noise ratio of the seismic data was increased, and the tectonic interpretation and lithological exploration can be carried out.(2)After comprehensive judgment based on illumination analysis, the first scheme is commended.24L8S136R204F observation system is used in the south area, and 24L8S144R108F observation system is used in the north area. The signal to noise ratios of target strata below-220m could be accepted, density of the resources were small, the cost was relatively low, the concentration ratio were high, and it was convenient to operate. According to the offset distribution in the first scheme, both the near offset and the far offset were uniformly covered, and the offsets within 200m were almost full-covered. The near offset uniformly coverage was beneficial to the imagination of ultra-shallow layers and unconformities.(3)In the complex fault belt of Biyang, tomographic static correction is more effective than refraction static correction and elevation static correction. The bending and discontinuous events became more natural and fluent, and the signal to noise ratio were increased. After tomographic static correction the shallow events details were abundant, and the frequency were improved. Thus, the effect of in-phase stacking was achieved.(4)The forward operator and conjugate inverse was introduced in this paper. Pre-stack depth migration with shot domain wave equation continuation was completed. This algorithm is stable, and is available for complex velocity field, and the calculation precision is high. The methods were studied, to improve the imaging precision and calculating efficiency of the pre-stack depth migration with shot domain wave equation continuation. Signal fidelity of the migration results were relatively high, seismic reflection characters were obvious, and wave group characteristics of the main layer sections were clear. The geological phenomenon was abundant, and this made the strata tracing simple. The section imagination of small faults was clear, the breakpoint was determined, and the migration was reasonable. In the end, imagination of the fault system was improved obviously, the structural configuration was improved, the events were natural, and both the signal to noise ratio and the continuation were increased.(5)Chopping functions were processed and optimized on floating datum, and high-density acquisition data were used effectively. The effective reflection information of shallow layers was maintained, and the shallow unconformities were clear.(6)The resolution of the results was improved effectively. The frequency band were relatively wide, and the effective reflection frequencies were 5～100Hz. Dominant frequencies of the upper second and third member of Hetaoyuan formation (500ms and the above of the section) reached 45～50Hz. Dominant frequencies of the lower third member of Hetaoyuan formation (700ms～1700ms of the section) reached 30～40Hz. Imagination of the basement was accurate, and the morphology was clear, which were available to do research on regional tectonics, sedimentary evolution, and stress analysis.The innovative points of this paper are as follows:(1)The forward operator and conjugate inverse was introduced in this paper. Pre-stack depth migration with shot domain wave equation continuation was completed. This algorithm is stable, and is available for complex velocity field, and the calculation precision is high. The methods were studied, to improve the imaging precision and calculating efficiency of the pre-stack depth migration with shot domain wave equation continuation. Signal fidelity of the migration results were relatively high, seismic reflection characters were obvious, and wave group characteristics of the main layer sections were clear. The geological phenomenon was abundant, and this made the strata tracing simple. The section imagination of small faults was clear, the breakpoint was determined, and the migration was reasonable. In the end, imagination of the fault system was improved obviously, the structural configuration was improved, the events were natural, and both the signal to noise ratio and the continuation were increased.It is the first time that the wave equation modeling and seismic illumination method applied in the geometry design, the result is very well. The technology meets the requirement of high density, wide azimuth, equal offset and fold number in acquisition parameters. It makes the equal and all azimuth observation of the geological target become reality.更多还原