Sills as fractured hydrocarbon reservoirs: examples and models
Sills as fractured hydrocarbon reservoirs: examples and models
复制标题
DOI：
10.1144/sp374.5
复制
发表时间：
2012-09
期刊：
影响因子：
--
通讯作者：
Agust Gudmundsson;Ingrid Fjeldskaar Løtveit
中科院分区：
文献类型：
--
作者：
Agust Gudmundsson;Ingrid Fjeldskaar Løtveit
摘要岩床在沉积盆地中很常见，通过热效应，它对有机质转化为油气有重要作用。此外，许多岩床作为油气储层，或者作为盖层，或者作为裂缝储层。在岩床与其寄主岩石之间的接触处，密封与玻璃质边缘和/或低渗透性变质寄主岩石有关。如果岩墙/断层的渗透率较低，则可在岩床-断层或岩床-岩墙接触处促进储层形成。如果岩床下边缘的密封破裂（由于构造载荷的变化），而上边缘的密封保持不变，则岩床本身可能充当裂缝性油气藏。沉积盆地中的主要岩床多为c型。15-150米厚，主要由（薄得多的）堤坝供水。堤坝向岩床的偏转主要是由于三个相关因素：（1）馈线堤坝前面的接触打开（“库克-戈登脱粘”）;（2）堤坝遇到层，局部应力不利于堤坝，但有利于岩床（“应力屏障”）;（3）接触面上杨氏模量的突然增加（“弹性失配”）。理论模型预测的共同横向尺寸/最大厚度（纵横）比的门槛在150和500之间，与实际测量的门槛尺寸。目前，世界上许多厚岩床被用作油气藏。
Abstract Sills are common in sedimentary basins and, through thermal effects, may contribute significantly to the transformation of organic material into oil and gas. In addition, many sills act as hydrocarbon reservoirs, either as seals or as fractured reservoirs themselves. The seals are related to glassy margins and/or low permeable metamorphosed host rocks at the contacts between the sills and their host rocks. Reservoir formation may then be encouraged at sill-fault or sill-dyke contacts, provided the dykes/faults have low permeabilities. If the seal at the lower margin of a sill is ruptured (because of changes in tectonic loading) while the seal at the upper margin is maintained, the sill may itself act as a fractured hydrocarbon reservoir. Major sills in sedimentary basins are mostly c. 15–150 m thick and are mostly fed by (much thinner) dykes. Deflection of dykes into sills is primarily due to three related factors: (1) opening of contacts ahead of the feeder dyke (the ‘Cook–Gordon debonding’); (2) dykes meeting layers with local stresses unfavourable to dykes but favourable to sills (‘stress barriers’); and (3) abrupt increase in Young's modulus (‘elastic mismatch’) across a contact. Theoretical models predict common lateral dimension/maximum thickness (aspect) ratios of sills between 150 and 500, in agreement with actual measurements of sill dimensions. Many thick sills worldwide are currently exploited as hydrocarbon reservoirs.