| Author's Name: HUANG Junping, LI Xiangbo, HE Wenxiang, LIN Junfeng, XU Yaohui, BAO Hongping,
WANG Hongbo, ZHANG Guisong, WANYAN Rong, WANG Yating |
| The Cambrian in Ordos Basin of North China Plate has great exploration potential. Based on the study of North China plate tectonic paleogeographic pattern, source rock distribution characteristics, hydrocarbon generation capacity, hydrocarbon generation and expulsion stages and development model, the exploration potential of deep Cambrian in Ordos Basin is clarified and the next favorable exploration direction is pointed out. The results show that: (1) A set of high abundance and high-quality source rocks (mainly shale) were developed in the Lower Cambrian in southern margin of Ordos Basin, with the thickness up to 80m, with an average organic carbon content of 3.14% and a maximum of 9.19%; the kerogen type is mainly type Ⅱ, with a small amount of typeⅠ; the equivalent vitrinite reflectance is greater than 2%, which is in the high or over mature stage. (2)The development of Lower Cambrian source rocks is jointly controlled by tectonic setting, continental margin slope and deep-water bay of under-compensated environment: on the one hand, the early formed paleogeomorphic background and deep-water bay jointly control the development scale of source rocks, which makes the source rocks more developed in ancient grooves or fault depression areas and deep-water bay areas; on the other hand, the strong reduction environment makes the source rocks have high organic abundance and hydrocarbon generation potential. (3)The source rocks of Lower Cambrian have two stages of hydrocarbon generation and expulsion. In the early stage, large-scale hydrocarbon generation and expulsion occurred in the Late Permian to Middle Triassic, when the Qinling Mountains had not been uplifted significantly, and the south margin of the basin was a southward inclined slope; in the late stage, the secondary hydrocarbon generation occurred in Mesozoic-Cenozoic in Fuping-Luochuan Bay and Weihe Basin developed in Cenozoic with weak tectonic activity. Therefore, the Qingyang paleo-uplift in southern margin of the basin and the uplifted areas on both sides of Fuping-Luochuan Bay are favorable locations for hydrocarbon migration, which have great exploration potential. |
