Abstract:

Abstract: The author proposed four major special conditions for hydrocarbon accumulation in large saline lacustrine basins of inland plateau (such as the western Qaidam area). First, their sedimentary environment is similar to that of modern Qinghai Lake, featuring in unique deposition conditions such as multisource, small systems, narrow facies belt and multiple types. Secondly, controlled by unique geological background and water medium, they share the pattern of one hydrocarbongeneration depression with a number of kitchens. Thirdly, different from other large inland lake (such as the Ordos Basin) with a single hydrocarbon migration potential, they have the advantage of multidirectional migration potential of oil and gas. Finally, reservoirs in active regions at higher altitude show a “selfclosed” pooling pattern. Based on the above four specific reservoiring conditions, the author proposed that oil and gas exploration in western Qadam Basin shall not only focus on delta front deposits, but also on the following three targets: beach bar sand, algal limestone as well as slump and turbidite sandbody caused by earthquakes. In addition, the abovementioned features determine that the oil fields in western Qaidam have the characteristics of nearsource accumulation, wide distribution, small but numerous oil/gas fields. Thus the exploration should be mainly brought before areas close to the main kitchens, such as Altun, Gansen and along Honggouzi. Meanwhile, the understanding of socalled “selfclosed” reservoiring pointed out that the uplifted basin margin be the main areas for future reserve growth.

Key words:  , Key words： special hydrocarbon accumulation condition, saline lacustrine basin of inland plateau, exploration significance, western Qaidam Basin