Proximal to distal fan change in grain size, clay matrix content, and grain-coating clays have been identified as key contributing factors for eservoir quality evolution of submarine fan turbidite sandstones. This study evaluated the role played by grain-coating and pore-filling clays, depositional facies, and diagenesis in reservoir quality evolution of the Paleocene Forties submarine fan sandstones (Central North Sea) from proximal to distal fan settings. To help provide a comprehensive understanding of the role played by pore-filling and grain-coating clays in destroying and preserving reservoir quality, respectively, in turbidite sandstones, we have used a multi-disciplinary approach including petrography, burial history, scanning electron microscopy, and stable isotopes analysis. Results of the study showed that reservoir quality is influenced by both depositional facies and diagenesis. The proximal-fan, amalgamated sandstones facies have the best reservoir quality due to coarser grain size, lower pore-filling clays, and lower amount of ductile grains. In contrast, the distal-fan, mud-prone heterolithic facies have the poorest reservoir quality due to finer grain size, higher pore-filling clays, and higher amount of ductile grains. Pore-filling clays between 10 and 30% have a deleterious effect on reservoir quality, reducing porosities and permeabilities to generally <10% and <1 mD, respectively. Based on the relatively shallow, present-day burial depths of the studied Forties Sandstone Member (2200–3100 m TVDSS), the percentage of clay-coating coverage to significantly inhibit quartz cementation ranges from 40 to 50%. Detrital, grain-coating smectites, probably inherited from the shelf/continental environments and/or emplaced through sediment dewatering, have transformed into chlorite, illite, and illite-smectite. Calcite and siderite, where well-developed, have arrested mechanical compaction and also occluded porosity, thereby rapidly degrading reservoir quality in the sandstones; however, their dissolution by acidic pore fluids could potentially create secondary intergranular porosity, enhancing reservoir quality of the sandstones. Evidence presented demonstrates that, high quality reservoir sandstones that deviate from normal porosity-depth trends for submarine fans sandstones can be attributed to facies changes (composition and grain size) with a complex interplay of mechanical compaction, detrital clays and authigenic clay coatings inhibiting quartz cement precipitation.

扇形颗粒尺寸，黏土基质含量和覆层粘土的近端至远端扇形变化已被确定为海底扇形浊积砂岩储层质量演变的关键因素。这项研究评估了颗粒涂层和孔隙填充粘土，沉积相和成岩作用在古近40年代海底扇形砂岩（北海中部）从近端扇形到远端扇形环境中的作用。为了全面了解孔隙填充和颗粒涂层粘土分别在破坏和保持浊度砂岩中的储层质量方面所起的作用，我们采用了多学科方法，包括岩石学，埋藏史，扫描电子显微镜，和稳定的同位素分析。研究结果表明，储层质量受沉积相和成岩作用的影响。由于扇形颗粒尺寸较大，孔隙填充粘土含量较低和韧性颗粒含量较低，扇形，近端混合砂岩相具有最佳的储层质量。相比之下，扇形，泥浆易生的异质岩相由于较细的粒度，较高的孔隙填充粘土和大量的可延展颗粒而具有最差的储层质量。孔隙填充粘土含量在10％到30％之间会对储层质量产生不利影响，从而将孔隙率和渗透率分别降低到通常<10％和<1 mD。根据研究的四十年代砂岩成员（2200–3100 m TVDSS）相对较浅的当今埋藏深度，显着抑制石英胶结的粘土涂层覆盖率范围为40％至50％。可能是从陆架/大陆环境中继承和/或通过沉积物脱水而沉积的，具有碎屑的蒙脱石蒙脱石已转变为绿泥石，伊利石和伊利石-蒙脱石。方解石和菱铁矿，发育良好，已经阻止了机械压实作用，并且还阻塞了孔隙，从而迅速降低了砂岩的储层质量。然而，它们被酸性孔隙流体溶解可能潜在地产生次生的粒间孔隙度，从而提高了砂岩的储层质量。所提供的证据表明，