| Halahatang Oilfield in the northern Tarim Basin was discovered in 2009, and obtained proven oil geological
reserves of 2.47×108 t in the Ordovician carbonates by 2015. It is an important field for increasing reserves and production
of crude oil from carbonate rocks in Tarim Basin. However, the geological conditions of the oilfield are so extremely
complex that geological understanding and exploration guidance have undergone many changes, and Halahatang Oilfield
has experienced many types of hydrocarbon reservoir exploration stages, such as siliciclastic rock trap, reef-shoal
reservoir, interlayer karstic reservoir and fault-related karstic reservoir. Based on comprehensive analysis of the
exploration history and exploration and development production data of the oilfield, it is recognized that the fracture-cave
reservoir controlled by multiple factors such as faults, karstification and unconformity is the major place for oil and gas
occurrence. Further, the distribution and enrichment of oil and gas controlled by the strike-slip faults have complex rules,
and the strike-slip faults could connect the Cambrian source rocks to form large-scale petroleum accumulation and
preservation. The exploration example of Halahatang Oilfield shows that the superior petroleum geological conditions are
the basis for the formation of large oil fields, the breakthrough of geological understanding is the key to the discovery of
complex large oil and gas fields, the progress of geophysical prospecting technology is the guarantee for the exploration
and development of complex oil and gas fields, and the integration of exploration and development is an effective way to
rapidly increase the reserves and production of carbonate rocks. It is suggested that the discovery and exploitation of deep
complicated oilfield is depended on the favorable petroleum accumulation condition and geological understanding of the
explorer, and appropriate seismic technology and the integrated organization of exploration and development. This case
study has important reference significance for the exploration and development of complicate fracture-cave reservoirs. |
