【作者】 周祺；

【导师】 郑荣才；

【作者基本信息】 成都理工大学 ， 沉积学， 2009， 博士

【摘要】 鄂尔多斯盆地是中国天然气勘探最有潜力的盆地之一,其上古生界具有巨大的天然气勘探潜力。长北气田位于盆地东部,属于西倾单斜构造背景上的河道岩性-地层圈闭气藏,具有薄层、低孔、低渗、低压、低产和非均质性强等特点,开发难度大,尤其是利用水平井开发如此薄层的非均质性严重的河道砂岩气藏难度更大。随着该气田水平开发井的逐步实施,其含气砂体规模及砂体边界的不确定性以及由于各井块开发程度的不均一性而导致的地层压力不均衡等地质难题都日益显现出来,这些都给该气田的全面评价、水平开发井部署和井轨迹的调整带来困难,并可能引起更大的勘探开发风险。针对目前所存在的地质问题,本论文以63口钻井的岩矿资料和测井资料为主要分析对象,运用储层沉积学、层序地层学、测井地质学等多学科交叉的综合研究方法,对长北气田上古生界二叠系山西组2段进行沉积体系、层序地层、岩相古地理、砂体展布三维可视化、储层特征以及储集砂体综合评价和有利区预测等方面进行系统和深入的研究,为更有效地勘探开发长北气田提供科学依据。通过上述研究,本论文在以下方面取得了一些进展和创新:1.对长北气田山2段开展了精细沉积相研究,确定该地区山2段属于海相辫状河三角洲沉积体系,并对该三角洲沉积体系的各亚相、微相和砂体展布特征与演化规律进行了详细研究,建立了自北向南延伸的辫状河三角洲沉积模式。2.应用高分辨率层序地层学原理及其技术方法,对研究区山2段进行了高分辨率层序地层分析,划分出1个长期、2个中期、4个短期和9个超短期基准面旋回层序,详细描述了各级次基准面旋回层序的结构类型、叠加样式、沉积序列与分布模式,讨论了中期、短期和超短期基准面旋回结构与储层发育的关系。同时在高分辨率层序地层等时对比的基础上,建立了长北地区山2段高时间精度分辨率的等时地层格架,并在地层格架中对砂层、小层砂体、单砂体进行了劈分和等时追踪对比,提出了分别相当中期、短期、超短期半旋回的砂层(大尺度)、小层砂体(中尺度)、单砂体(小尺度)的地层单元划分方案。3.以高分辨率层序分析和地层等时追踪对比为基础,采用层序-岩相古地理编图技术,选择分别相当砂层和小层砂体级别的中期、短期半旋回为等时地层单元,编制了长北气田山2段短时间尺度的沉积微相分布图,并以相控建模为指导思想,结合序贯指示数学方法,依次选择分别相当短期和超短期半旋回级别的小层砂体和单砂体为等时地层单元,建立长北气田山2段短时间尺度的砂体三维可视化模型。在深入讨论中期、短期半旋回沉积微相分布特征的基础上,总结了砂体的成因类型、几何形态、平面展布和演化特点,深入分析了基准面旋回与储层发育和储层品质的关系,为进一步的高渗带预测和评价奠定了基础。4.深入细致地研究了长北气田山2段储层特征,在砂岩储层孔隙结构和物性分析基础上,确定储集空间以剩余原生孔隙和次生粒间溶孔为主,部分为破裂缝及粒缘缝,总体上属于低孔-低渗孔隙型储层;5.在总结成藏基本地质条件的基础上,选择砂体累计厚度、砂岩密度、钻遇率、物性和砂体空间展布特点等因素为综合定量评价指标,对长北气田山2段小层砂体和单砂层有利发育层位与相对高渗区带进行了定量评价,从山2段中评价出3个最有利小层砂体发育层位、5个最有利和4个较有利单砂体发育的层位,并在此9个单砂体发育的层位中预测了9个具备优越岩性-地层圈闭条件的相对高渗区带和单砂体连续叠置有利预测区。更多还原

【Abstract】 Ordos basin is one of the most potential gas reservoir region in China and the Upper Paleozoic is the important exploration target. Changbei gas field is a river lothology-stratigraphic trap gas pool on the west trend monocline background, it is located in the east of the basin, it has thin bed, low-porosity, low-permeability, low-pressure, low-deliverability character and develop difficulty(HeGuang-huai, 2002), especially to develop this thin bed and unhomogeneity seriously river sandbody gas pool is much difficulty. Along with horizon development well to implement, some problem became more and more gravity, such as sandbody’scale and sandbody’boundary was uncertainty and layer pressure was uneqilibrium for different well area development degree is not community. These taked a few difficulty of comprehensive evaluaterating, deploying horizon development well, adjusting well trackway for the gas field, and it might take any geologic risk.Aimed at these problem, this paper taked 63 well drilling’s rock mineral document and logging document as main analysis object, combined reservoir sedimentology, sequence stratigraphy, logging geology together to research sedimentary system, sequence stratigraphy, lithofacies paleographic, sandbody distribution three dimensional visualization, reservoir character and reservoir sandbody comprehensive evaluation, it offers reference and criterion for Changbei gas field gas reservoir’s exploration and development.Based on the above researching, this paper has been gained some progesses and innovations:1. We have taked sedimentary facies research on the second member of Shanxi formation of Changbei gas field, this area pertained to marine facies braid river delta sedimentary system, we have gived a detailed discriiption on different subfacies, microfacies, sandbody’s sedimentary character and distribution for the braid river delta sedimentary system. Based on it, we have been constructed fluvial dominated delta sedimentary model from north to south.2. Using high-resolution sequence stratigraphy theory and technique method to analyse sequence on Changbei gas field, we divided it to one long-term, two middle-term, four short-term, nine super short-term basal level cycle sequence and discrpited its structure model, sedimentary series, distribution model, discussed the relation between middle-term, short-term, super-term basal level cycle structure and resevoir growth. And then based on the high-resolution sequence stratigraphy equitime comparison, constructed high-resolution of accuracy degree’s equitime stratigraphy framework, choped and equitime traced on sand layer, small sandbody, single sandbody, putted forward a Stratigraphy dividing scheme to sand layer(big scale), small sandbody(middle scale), single sandbody(small scale).3. Based on high-resolution sequence analysis and stratigraphy equitime trace comparison, taked sequence-lithofacies palaeogeographical technique, choosed middle-term and short-term hemiscycle which equivalented to sand layer and small sandbody as stratigraphy unit, compiled a few short time scale sediment microfacies picture. And then taked phase control construction model as direction, combined sequential indication mathematics method, choosed middle-term and short-term hemiscycle which equivalented to sand layer and small sandbody as equitime stratigraphy unit, constructed short time scale’s sandbody three dimensional model. Based on the middle-time and short-time hemicycle sediment microfacies distribution foundation, sumed sandbody’s genetic type, geometric shape, flat distribution and evolution character, analyzed the relations between reservoir quality and base level cycle, this offers to futher forecast and evaluate for high permeability zone.4. After researched on the reservoir character of changbei gas field, based on the sand stone reservoir pore structure and physical property, we have certained accumulation space was remainder primary pore and secondary intergranular dissolved pore, break seam and grain boundary seam forms fragmental rock accumulation space. Accumulation type is mained as low pore and low permeability reservoir.5 Based on the basic geology condition foundation, choosed sandbody total thickness, sand stone density, drilling encounter rate, physical property, reservoir growing situtation and sandbody space distribution character as ration evaluation indicator, we have constructed small layer sandbody and single sandbody comprensive indication system and have taked quantitative evaluation to small layer sandbody and single sandbody’s beneficial growth layer and high permeability zone of the two member of Shanxi formation. From these evaluation, we have got five best beneficial single sandbody layer and four relative beneficial single sandbody layer and have forecasted nine high permeability zone of advantageous litho stratigraphic trap condition and two sandbody continuous overriding beneficial prediction zone..更多还原