“两宽一高”地震资料在花岗岩潜山储层表征中的应用——以乍得邦戈盆地为例

Granitic buried-hill reservoir characterization based on broadband,wide-azimuth and high-density seismic data:A case study of Bangor Basin in Chad

随着乍得邦戈盆地在L-1井区的花岗岩潜山获得油气发现,在该区开展了"两宽一高"(宽方位、宽频带、高密度)的油气勘探地震资料采集处理解释一体化技术攻关。充分利用"两宽一高"地震资料的高信噪比、全方位观测、低频信号的强穿透能力和抗干扰能力等优势,有效提高了潜山顶面偏移成像质量,获得了丰富的潜山内幕信息,为花岗岩型潜山的储层表征和潜山目标评价奠定了良好基础。本文基于"两宽一高"地震资料提出了花岗岩潜山复杂储层表征技术,根据储层的储集空间组合特征、储层类型、岩石物理特征和对应的地震响应特征,将花岗质基岩潜山储层序列划分为风化淋滤带、缝洞发育带、半充填裂缝发育带和致密带;将裂缝型和孔隙型储层分类表征,孔隙型储层通过地震多属性融合和地震反演技术进行储层定性和定量预测,裂缝型储层结合区域构造特征,分别应用曲率体、相干和OVT域地震属性等进行裂缝识别与预测;综合裂缝预测和孔隙型储层预测结果进行储层评价和优质储层预测。该配套技术在乍得邦戈盆地的实践表明,应用"两宽一高"地震资料及针对性配套技术,能有效提高邦戈盆地花岗岩潜山储层预测的精度和勘探成功率,在B区块实施的潜山探井成功率高达79%。

After the oil discovery in granitic buried-hill reservoirs in Bangor Basin,Chad,a broadband,wide-azimuth,and high-density(BWH)seismic acquisition survey was carried out and the data was appropriately processed.The BWH seismic data are characterized by high SNR,all azimuth measurement,and strong-penetrating low frequency energy,which improves greatly buried-hill top imaging.Detailed interior information of granitic buried-hills provides a solid foundation of reservoir characterization and exploration target evaluation.Based on BWH data reservoir characterization,we first classify granitic reservoirs into weathering-leaching zone,fracture-cavity zone,semi-filled fracture zone,and tight zone.Then we characterize respectively fractured reservoirs and porous reservoirs,predict porous reservoirs with multi-attribute fusion and seismic inversion,and identify fractured reservoirs with curvature cube,coherence cube,and OVT attritute.Finally we conduct reservoir evaluation and favorable reservoir prediction on fractured and porous reservoirsprediction.Our application in Bangor Basin indicates that our approach on BWH seismic data characterizes precisely granitic buried-hill reservoirs,and the drilling success rate based on our well deployment proposal is up to 79%.