塔里木盆地顺北地区海相超深层碳酸盐岩是塔里木盆地油气勘探的重点领域之一。经过地震采集、处理成像、量化识别和地质工程一体化解释的系统攻关, 逐渐形成了高密度、高精度、面向缝洞体的三维地震采集技术; 宽频带、高保真全波场地震处理技术; 叠前宽方位分析、各向异性检测、可视化等多维度解释技术。但作为典型的非层状油气藏, 塔里木盆地顺北地区海相超深碳酸盐岩油气地震勘探理论与地震勘探实践仍面临全方位的挑战, 未来应进一步加强物探技术攻关, 包括进一步完善地震散射波传播与成像理论; 试验以“共中心点离散化、近偏高覆盖、多观测系统”为主的地震采集技术; 重新认识噪声, 实现多态式地震波处理和全波场地震成像; 积极探索智能化解释技术, 综合岩石物理分析与正演模拟、多态式的叠前反演与地震属性分析, 精细描述缝洞体及其内幕。这些技术对支撑顺北地区持续重大突破和持续发展, 以及对国内外超深层碳酸盐岩勘探和非层状油气藏勘探具有借鉴意义。

回顾了中石化在塔里木盆地油气勘探的历程, 总结了经验、教训, 明确了中石化在塔里木盆地取得的三大油气勘探成果。梳理了塔里木盆地不同探区、不同类型油气藏勘探难点, 总结了主要物探技术进展及应用成果。油气勘探实践结果表明, 大油气田的发现离不开勘探理论创新和技术进步, 特别是三维高精度地震勘探技术。面对更深、更小、隐蔽性更强的勘探目标, 提出了需要夯实地震波场发育机理基础研究, 发展超深层低信噪比区高精度地震采集技术, 攻关低序级断裂、小尺度缝洞目标处理技术及山前复杂速度场条件下构造成像技术, 探索人工智能技术、叠前叠后联合应用技术在强非均质性碳酸盐岩缝洞储层预测及油气检测中的应用研究。

叠前深度偏移速度建模是一种基于模型的迭代修正过程。影响速度模型精度的因素,除了速度反演算法之外,还包括复杂近地表条件下的静校正处理和观测系统的不规则性。从地震资料处理解释一体化的研究思路出发,针对不同的地震地质条件,提出了建立精确速度模型的对策。在地震勘探程度较高的地区,首先采用测井约束法建立初始宏观层速度模型,然后利用多域双重迭代法进行优化更新,以达到满足叠前成像精度要求的目的。另外,针对我国西部山地冲断带地区速度建模存在的问题,提出了速度建模的思路和对策,并对该项技术的发展趋势进行了展望。

Velocity model building for prestack depth migration is a model-based iteration process. Besides velocity inversion algorithm, the static correction in complex near-surface condition and irregular geometries may also impact the velocity modeling. Based on integrating seismic processing and interpretation, aimed at different seismic-geological conditions, the strategy of accurate velocity model establishment is proposed. In some high degree exploration areas, the initial macro interval velocity model is firstly established by u-sing the logging-constrained method, and then, the double-iteration method in multi-domains is applied on velocity model updating to meet the accuracy of prestack imaging. In addition, based on some problems in velocity modeling in the foreland basin of west China, the thought and strategy for velocity modeling are proposed and the development tendency of this technique is analyzed.

中国石化资源禀赋相对较差,围绕东部老区小规模隐蔽圈闭精细描述难、西部深层超深层碳酸盐岩孔缝洞储层成像刻画精度低、非常规领域一体化程度不高等重点领域的油气勘探开发难题,形成了单点高密度地震采集、以叠前逆时偏移成像(RTM)为核心的高精度成像、地震多属性分析以及叠前叠后储层反演等技术系列,有效提高了地震资料品质,助力稳油增气降本。东部老区主要目的层沙三段优势频带扩宽了20Hz以上,有效提高了隐蔽圈闭识别精度;四川盆地超深层生物礁储层预测结果与实钻吻合率达到93%;塔里木盆地顺北超深层断控储集体实现了量化描述,有效支撑了SHB4X、SHB8X等日产千吨井的部署;初步形成非常规领域地质物探工程一体化技术,中国石化率先探明了国内首个千亿方常压页岩气田。在取得勘探新成果的同时,中国石化地球物理勘探当前还面临着物探技术对勘探领域拓展和勘探部署支撑的力度不够;物探精度尚不能满足复杂地质目标识别的要求;装备软件“卡脖子”问题依然存在;技术集成和攻关合力不够等4个方面的挑战。展望未来,针对中国石化东部断陷盆地、深层超深层海相碳酸盐岩、中西部致密碎屑岩、山前带、非常规、海域、火成岩七大重点领域的油气勘探开发难题及物探技术需求,需要提升完善6项核心技术,支撑当前勘探开发;攻关研究5项关键技术,突破技术发展瓶颈;探索储备2项前沿技术,引领未来技术发展。

Sinopec's resource endowment is relatively poor.Various technologies have recently been proposed to improve the quality of seismic data,thereby addressing oil and gas exploration and exploitation issues in key fields,such as the challenging fine description of small-scale subtle traps in the eastern old oilfields,low imaging accuracy of deep and ultra-deep carbonate porous-fractured and cavernous reservoirs in the western oilfields,and low degree of integration in unconventional fields.These technologies include the single-sensor-based high-density seismic acquisition,high-precision imaging of prestack reverse time migration imaging,multi-attribute analysis,and prestack and poststack reservoir inversion.The dominant frequency band of the third member of the Shahejie Formation,that is,the main target layer in the old exploration area of the eastern oilfields,could be widened by more than 20Hz,leading to a significant improvement in the identification accuracy of subtle traps.Thus,the coincidence rate between predictions and drilling results for ultra-deep reef reservoirs in the Sichuan Basin reached 93%.The ultra-deep fault-controlled reservoirs in the Shunbei Tarim Basin were quantitatively analyzed,supporting the deployment of 1000 ton/day wells such as SHB4X and SHB8X.A technology integrating geological,geophysical,and engineering exploration methods for unconventional fields was established at Sinopec.Thus,Sinopec took the lead in exploring the first 1011 m3 of normal-pressure shale gas fields in China.Despite the exploration achievements,geophysical exploration activities at Sinopec are still facing four challenges:Ⅰ) technical support for expanding the exploration areas and subsequent well deployment are insufficient;Ⅱ) accuracy of current technologies is insufficient for identifying complex geological targets;Ⅲ) equipments and softwares are strangling the development;Ⅳ) integration among technologies is insufficient.Considering the aforementioned issues that condition the activities in seven key areas (namely the eastern rift basin,deep-ultra deep marine carbonate rock formations,dense clastic rock formations in central and western China,the piedmont belt,unconventional resources,the maritime space,and igneous rock formations),six core technologies should be improved in the future to support the exploration and exploitation;five key technologies should be studied to overcome the bottleneck in technological development;and two cutting-edge technologies should be developed to lead the future technological development.

塔里木盆地顺北地区地表沙丘起伏大,地震信号吸收衰减严重,断溶体储集体埋藏深度大,纵横向非均质性强,因而断溶体(断裂、缝洞)成像精度不高、储层预测与圈闭描述难度大。为此,在该区系统开展了三维地震采集、目标处理、综合解释一体化技术攻关。首先,基于断溶体目标优化采集方案设计,采用中小面元、长排列、宽方位、高覆盖的观测系统,尽可能保护断裂绕射、缝洞体低频信息,提高采集数据质量;其次,在保幅、保真的前提下,建立了以“三层一带”精细速度建模为核心的断溶体成像技术,提高缝洞及不同尺度走滑断裂带的成像精度;再次,依据断溶体储层类型及反射结构特征,建立了走滑断裂带及断溶体储层地震识别模式,开展储层敏感属性分析,形成针对断溶体外部轮廓、内部不同类型储层的一系列储层预测及流体检测技术;最终,建立了“张量属性定轮廓、振幅属性定边界、融合雕刻定体积”的圈闭落实与描述技术,形成了“打主断、过异常、穿核部”目标优选与井轨迹优化设计技术。探区多口钻井实现了油气重大突破,证实了顺北沙漠区超深断溶体油气藏三维地震勘探技术的有效性及适用性。

<p>Fault-related dissolution reservoirs are buried deeply in the Shunbei area of the Tarim Basin and exhibit a high heterogeneity.Moreover,the surface dunes fluctuate greatly,and the seismic attenuation is severe.This results in a low imaging accuracy of the fault-related dissolution body (fractures and fracture-vugs),and in difficult reservoir prediction and trap description.Therefore,an integrated exploration method consisting of three-dimensional seismic acquisition,target processing,and comprehensive interpretation was carried out systematically in the study area.First,the acquisition design scheme for fault-related dissolution bodies was optimized.The surveying scheme was characterized by small or medium-sized bins,long seismic spread,wide azimuth,and high coverage to preserve the diffraction from fractures and the low frequency information for fractures and cave bodies,thereby improving the quality of the acquired data.Second,on the premise of amplitude and fidelity preservation,velocity modeling and imaging techniques with preservation of amplitude and fidelity were implemented.The latter included pre-stack time migration and reverse-time depth migration imaging,to improve the imaging accuracy of fracture-vugs and strike-slip fault zones at different scales.Third,according to the types of fault-related dissolution bodies and the characteristics of the reflection configuration,the seismic identification patterns of strike-slip fault zones and fault-related dissolution reservoirs were identified,and the sensitive attributes of the reservoirs were analyzed.A series of reservoir prediction and fluid detection techniques for reservoirs located outside and inside fault-related dissolution bodies was developed.Finally,a technique for trap description was proposed,which uses the gradient structure tensor attribute to determine the outline,the amplitude attribute to describe the boundary,and the fusion engraving technique to determine the volume of the dissolution body.Moreover,a technology for target and well trajectory optimization was proposed,which aims at &ldquo;drilling through the main fault,the seismic anomaly,and the core of the fault&rdquo;.By carrying out several drilling wells great breakthroughs in oil and gas exploration have been made in the study area,thereby proving the validity and applicability of the three-dimensional seismic exploration technology for ultra-deep fault-related dissolution bodies in the Shunbei area.</p>