基于随钻电阻率成像测井分析的礁滩灰岩储层裂缝及次生溶蚀的精细表征——以珠江口盆地陆丰油田为例

Fine Characterization of Fractures and SecondaryDissolution in Reef-Shoal Limestone Reservoirs Based onLWD Resistivity Imaging Logging Analysis——A Case Studyof Lufeng Oilfield in the Pearl River Mouth Basin

陆丰X-1油田是近年来珠江口盆地东部勘探发现的优质礁滩灰岩油田,蕴含着丰富的油气资源,但灰岩储层岩性复杂、孔隙结构复杂及非均质性极强,为储层评价及油田整体开发带来了极大的挑战。通过将随钻高分辨率电阻率成像测井技术引入对礁滩灰岩沉积构造特征、裂缝精细表征、次生溶蚀定量计算及产能主控因素的研究中。结果表明:陆丰X-1灰岩油层纵向上可细分为ZJ10A及ZJ10B灰岩段,ZJ10A灰岩段主要为礁灰岩沉积,沉积构造主要表现为块状及层状特征;ZJ10B灰岩段主要为生物碎屑滩沉积,沉积构造以层状结构为主。以高分辨率电阻率成像资料为基础,确定了ZJ10A灰岩段主要发育高角度构造缝,裂缝有效性及纵向沟通性好;ZJ10B灰岩段裂缝类型以溶蚀缝及孤立缝为主,裂缝有效性及纵向沟通性相对较差。陆丰X-1灰岩油层发育斑杂状、团块状、蜂窝状及顺层状等多种次生溶蚀类型,利用电阻率频谱分析方法及PoroTex方法对陆丰X-1灰岩油层次生溶蚀孔隙度及视面孔率进行了定量计算,优质储层段次生溶蚀孔隙度及视面孔率均较高。综合电阻率成像测井解释成果以及动态生产资料对陆丰X-1灰岩油层产能主控因素进行了分析,次生溶蚀对产能是正向贡献而高角度构造缝则是负向贡献。高分辨率成像测井技术在陆丰X-1油田礁滩灰岩层段的成功应用既满足了储层精细表征的需求,又为陆丰X-1油田后续整体开发提供了坚实的数据基础。

Lufeng X-1 oilfield is a high-quality reef-shoal limestone oilfield discovered during exploration in the eastern Pearl River Mouth Basin in recent years.Abundant oil and gas resources are discovered in this oilfield,but the limestone reservoir is characterized by complex lithology,complex pore structure,and strong heterogeneity,which bring great challenges to reservoir evaluation and overall oilfield development.In this paper,high-resolution LWD(Logging While Drilling)resistivity imaging logging technology was utilized to study the sedimentary environment analysis,fine characterization of fractures,quantitative calculation of secondary dissolution,and main controlling factors of productivity of reef-shoal limestone.The results show that the Lufeng X-1 limestone oil layer can be subdivided vertically into ZJ10A and ZJ10B limestone sections.The ZJ10A limestone section mainly develops reef limestone with the texture of massive bedding and laminated bedding.The ZJ10B limestone section was mainly deposited in bioclastic beach environments,with the sedimentary texture of laminated bedding.Based on high-resolution resistivity imaging data,it is determined that the ZJ10A limestone section mainly develops highangle structural fractures,with good fracture effectiveness and vertical communication.Dissolved fractures and isolated fractures are developed in ZJ10B limestone section,with poor fracture effectiveness and vertical communication.Various secondary dissolution types are developed in Lufeng X-1 oilfield,including mottled,lumpy,honeycomb and bedding dissolution.The resistivity spectrum analysis method and PoroTex method are used to quantitatively calculate dissolution porosity and apparent porosity,showing that secondary dissolution porosity and apparent porosity were both relatively high in the high-quality reservoir section.Combined resistivity imaging logging interpretation results and dynamic production data,main factors controlling the productivity of the Lufeng X-1 limestone oil layer were comprehensively analyzed.Secondary dissolution contributes positively to productivity,while high-angle structural fractures contribute negatively.The successful application of highresolution imaging logging technology in the reef-shoal limestone section of the Lufeng X-1 oilfield not only meets the needs for fine reservoir characterization,but also provides a solid data foundation for the subsequent overall development of the Lufeng X-1 oilfield.