Objective The architecture of marine sandy beach-bar reservoirs is complex, and dominant seepage channels and barriers are developed. The current lack of architecture models for underground reservoirs means that there are few effective guidelines for the recovery of residual oil. Methods A system is proposed for recognizing the architecture patterns of marine sandy beach-bar reservoirs from outcrops in the Hudson Donghe sandstone, obtained through the use of satellite photographs and numerical simulations. Results The depositional architecture of individual sand bars within composite beach-bars is affected by many factors (e.g., shoreline shape, coastal slope, wave direction and height). Multiple types of sandbar may be formed (e.g., conical bar, crescent-moon-shaped bar, positive linear bar, nonlinear inclined bar and sandy beach bar). Based on the identification of boundaries between individual sandbars, and guided by the architecture mode, 13 sandbars of different sizes were identified in the C1 layer in the study area, comprising five crescent-moon-shaped bars, seven forward linear bars and one oblique bar. Differences in scale are evident between different sandbar types: the length of crescent-moon-shaped bars is about 1.5-3.0 km; the length of oblique bars is about 4.5-5.0 km; and the length of positive linear bars is more than 6 km. The sandbars exhibit either progradational or retrogradational stacking patterns; bars in the C1 layer exhibit progradational lateral separation and progradational lateral stacking patterns. The migration rate of the coastline has affected the stacking relationship between the sandbars. Numerical simulations and outcrop observations indicate differences in the developmental patterns of the internal accretion bodies, including top accretion, top- and side accretion, and different interval types. Three internal interlayer patterns were identified in the C1 layer: a two-stage “top- and side-accretion” feature in the No. 16 sandbar, and “side accretion” in the No. 19 sandbar. The slopes of the top and side accretion interlayers range from about 1°-3° to 3°-7°. The layers between No. 14 and 15 sandbars are arranged in an “interval” pattern. Conclusions The fine characterization of the internal architecture of marine sandy beach-bar reservoirs described in this study can effectively guide the recovery of remaining oil.
| 科 Family | 属数 Number of genus | 种数 Number of species | 占总种数比例 Percentage of total species (%) | 属 Genus | 种数 Number of species | 占总种数比例 Percentage of total species (%) |
|---|---|---|---|---|---|---|
| 鹅膏菌科Amanitaceae | 2 | 11 | 5.26 | 鹅膏菌属 Amanita | 10 | 4.78 |
| 小菇科 Mycenaceae | 2 | 12 | 5.74 | 丝盖伞属 Inocybe | 5 | 2.39 |
| 多孔菌科 Polyporaceae | 8 | 14 | 6.70 | 蜡蘑属 Laccaria | 5 | 2.39 |
| 红菇科 Russulaceae | 3 | 23 | 11.00 | 小皮伞属 Marasmius | 6 | 2.87 |
| 小菇属 Mycena | 11 | 5.26 | ||||
| 光柄菇属 Pluteus | 5 | 2.39 | ||||
| 红菇属 Russula | 17 | 8.13 | ||||
| 栓菌属 Trametes | 5 | 2.39 |