摘要
以乍得Bongor盆地Baobab North油田P组为例,探讨重力流水道砂体的沉积机理及构型特征。结合岩心测井等资料,确定了P组的沉积背景,明确了单一水道的类型及其形态结构,探讨了单一水道内部的泥质夹层的构型特征及沉积机理。通过上述研究,认为Baobab North油田P组主要发育三类单一水道沉积,Ⅰ类水道垂向上粒度呈典型正韵律,测井曲线自然伽马和自然电位以钟形为主;Ⅱ类水道在垂向上粒度以均质韵律为主,测井曲线自然伽马与自然电位多表现为箱形;Ⅲ类水道在垂向上粒度呈反韵律,测井曲线自然伽马、自然电位等在水道下部幅度较低,呈齿化钟形;单一水道内部主要发育三类近水平分布的泥质夹层,连续型泥质夹层由于保存程度较好,测井曲线多呈半回返和全回返,平面上泥质夹层顺水流方向较长(100~450 m),垂直水流方向较宽(70~300 m),且厚度较大(0.3~0.8 m);垂向上夹层频率较高(0.13~0.7)、夹层密度较大(0.04~0.25)。间断型泥质夹层在水道中心部位被完全冲刷或只有很薄一部分被保留下来,测井曲线为半回返或弱回返,平面上泥质夹层顺水流方向较短(50~250 m),垂直水流方向较窄(40~200 m),厚度较薄(0.15~0.5 m);垂向上夹层频率较低(0.12~0.4)、夹层密度较小(0.04~0.14)。复杂型泥质夹层是指连续型泥质夹层和间断型泥质夹层在单一水道砂体中同时发育,该类泥质夹层的规模与频率居中,顺水流方向长度介于80~320 m,垂直水流方向宽度介于55~240 m,厚度介于0.25~0.6 m,夹层频率介于0.12~0.45、夹层密度介于0.04~0.18。
In order to study the architecture characteristics and sediment mechanism of the turbidity channel sandstone, this article takes the turbidity channel sandstone of Layer P of Baobab North Oilfields in Bongor Ba- sin for example. Under the guidance of sedimentary mechanism, the sedimentary environment of the Layer P is confirmed. The types and the structural features of the single turbidity channel sandstone are studied. And the architecture characteristics of the mud layers in the single turbidity channel sandstone are analyzed. Based on the research mentioned above, there are three kinds of single turbidity channel in the Layer P. The I type tur- bidity channels have a positive rhythm of the size distribution, and its GR and SP loggings are bell-shaped. The Ⅱ type turbidity channels have an even rhythm of the size distribution, and their GR and SP loggings are box- shaped. The Ⅲ type turbidity channels have a negative rhythm of the size distribution, and their GR and SP loggings are funnel-shaped. There are three kinds of mud interlayers in the single turbidity channel. The contin- uous type is preserved well and its loggings are near the baseline. Its length is between 100 m and 450 m along river flow direction. Its width is between 70 m and 300 m in the vertical direction of the river flow. Its thickness is between 0. 3 m and 0. $ m. Its distribution frequency is between 0. 13 and 0. 7. Its distribution density is be- tween 0. 04 and 0.25. The discontinuous type is hardly preserved and its loggings are far away from the base- line. Its length is between 50 m and 250 m along river flow direction. Its width is between 40 m and 200 m in the vertical direction of the river flow. Its thickness is between 0.15 m and 0.5 m. Its distribution frequency is between 0. 12 and 0.4. Its distribution density is between 0.04 and 0. 14. The complex type is mixed by both of the continuous type and discontinuous. Its length is between 80 m and 320 m along river flow direc- tion. Its width is between 55 m and 240 m in the vertical direction of the river flow. Its thickness is between 0. 25m and 0.6m. Its distribution frequency is between 0.12 and 0.45. Its distribution density is between 0.04 and 0.18.
出处
《现代地质》
CAS
CSCD
北大核心
2017年第3期555-564,共10页
Geoscience
基金
中国石油天然气集团公司科技重大专项(2011E2506)
