The restoration of palaeokarst geomorphology during Huaiyuan Movement and its petroleum geological significance in Ordos Basin
The unconformity of Huaiyuan Movement is a new exploration direction of Cambrian in Ordos Basin.The weathering crust karst reservoir developed at the top of the Cambrian under the exposure and leaching of meteoric water,but the paleokarst geomorphology has not been restored and it is difficult to meet the requirements of exploration.Based on the data logging,cores and field section,this work selects the top of Ma-3 member as the base level of palaeokarst geomorphology restoration in the overlying strata of Cambrian by stratigraphic classification,correlation and establishment of isochronous stratigraphic framework.According to the strata thickness of impression between the top of Cambrian and the top of Ma-3 member,the contour map of strata is drawn and the palaeokarst geomorphology is restored.Based on this,three paleogeomorphic units can be divided:karst highland,karst slope and karst basin,and the secondary geomorphic unit-monadnock can be divided into karst slope.During the Huaiyuan Movement,the study area was high in the west and low in the east topographically.The Qingyang,Tongxin and Erdos areas in the west were karst highlands,the Wushenqi and Dali monadnocks developed in the central belted karst slope,and Lüliang area in the east was karst basin.According to the relationship between palaeokarst geomorphic units and karst reservoirs,karst highlands and monadnocks in karst slopes are conducive to the formation of reservoirs and are favorable directions for natural gas exploration.
Palaeogeomorphologic restorationHuaiyuan MovementPalaeokarst of the weathering crustKarst reservoirOrdos Basin
万方数据
维普
