CBIL logs: vital for evaluating disappointing well and reservoir performance, K15-FG field, central offshore Netherlands
CBIL logs: vital for evaluating disappointing well and reservoir performance, K15-FG field, central offshore Netherlands
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CBIL 测井：对于评估令人失望的油井和油藏性能至关重要，K15-FG 油田，荷兰中部近海
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发表时间：
1993
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通讯作者：
H. W. Frikken
中科院分区：
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作者：
H. W. Frikken
K15-FG Rotliegend气藏的前两口开发井产能变化较大，流速急剧下降。物料平衡数据显示，该油田预计的初始产气（GIIP）只有30%与井相连。这种较差的表现反映了地层和构造的储层划分。在第二口开发井中进行了圆周井眼成像测井（CBIL）。CBIL能够识别小规模的储层非均质性和薄的、未被发现的高产风成层。测井分析还显示了一组共轭剪切裂缝的存在，这一点得到了岩心的证实。此外，还发现了与井径相交的小尺度亚地震分辨率反向断层，以及井周围的异常构造倾角，表明断层阻力。近井反断层和碎屑充填的亚垂直剪切裂缝的存在，限制了水平流入，解释了第二口井令人失望的产量。此外，从测井中观察到连续的钻孔突进，表明了当前的应力各向异性。CBIL数据结合在地震属性图上观察到的断层线，形成了整个油田的右旋扭曲概念，以及相关的逆断层和走滑断层或剪切带。这种部分封闭和完全封闭断层的构造是导致储层连通性差的主要原因，这一点已被压力行为所证实。CBIL是评价沉积和构造储层非均质性的有效工具。由此产生的解释通过解决异常井行为和油田结构的原因，为优化采收率创造了空间。通过对新钻的第三口开发井的压力分析，再次确认了油田内走滑断层的存在及其封闭性。
The first two development wells of the K15-FG Rotliegend gas reservoir showed a large variation in productivity and sharply declining flow rates. Material balance data indicated only 30% of the field’s expected Gas Initially In Place (GIIP) to be connected to the wells. This poor performance reflects stratigraphie and structural reservoir compartmentalization. A Circumferential Borehole Imaging Log (CBIL) was run in the second development well. The CBIL enabled identification of small-scale reservoir heterogeneity and thin, otherwise undetected highly productive aeolian layers. The log analysis also revealed the presence of a conjugate set of shear fractures, confirmed by cores. Furthermore, small-scale, sub-seismic resolution reverse faults were detected intersecting the well path, as well as anomalous structural dips around the well, indicating fault drag. The presence of near wellbore reverse faults and sub-vertical shear fractures with cataclastic fill, restricting horizontal inflow, explains the disappointing production rates of the second well. Moreover, continuous borehole break-outs were observed from the log, indicating present-day stress anisotropy. The CBIL data in combination with lineations observed on seismic-attribute maps contribute to a concept of dextral wrenching across the field, with related reverse faulting and strike-slip faults or shear zones. Such a configuration of partly and completely sealing faults is a major cause of the poor reservoir connectivity as confirmed by pressure behaviour. The CBIL is an effective tool for evaluating both depositional and structural reservoir heterogeneity. The resulting interpretations created scope for optimization of recovery by resolving the causes of anomalous well behaviour and field architecture. Pressure analysis of a recently drilled third development well has once more confirmed the presence and sealing character of strike-slip faults within the field.