Kuche Depression Research Articles

Sequential extraction and compositional analysis of oil-bearing fluid inclusions in reservoir rocks from Kuche Depression, Tarim Basin

The free oils, adsorbed oils and oil-bearing fluid inclusions have been extracted separately and analyzed by GC and GC-MS in reservoir rock samples collected from the Kuche Depression. The results demonstrate that the molecular compositions of oil-bearing fluid inclusions are significantly different from those of the free oils (the current oils). Compared with the current oil, the oil-bearing fluid inclusions are characterized by relatively high values of parameters Pr/nC17 and Ph/nC18, low values of Pr/Ph, hopanes/steranes, C30-diahopane/C30-hopane and Ts/Tm, low content of C29TS terpane and high maturities as indicated by C29 steranes 20S/(20R+20S). In addition, the oil-bearing fluid inclusions correlate very well with the oils in northern and central Tarim Basin, which were derived from Cambrian-Ordovician marine source rocks. The adsorbed oils appear to be an intermediate type between free oils and oil-bearing fluid inclusions. The above analytical data indicate that there are at least two oil-charging episodes for these reservoir rock samples. The early charging oils were derived from Cambrian-Ordovician marine source rocks, and the later charging oils, from Triassic-Jurassic terrestrial source rocks. The primary marine oils were overwhelmingly diluted by the following terrestrial oils.

Integration of 3-D seismic attributes with core and wireline log data for detailed modeling of Cretaceous fluvial reservoirs

Yakela Field, in the central Tabei Uplift in the northern Tarim Basin, northwest China, is bounded to the south by the Manjiaer‐Awati depressions and to the north by the Kuche Depression and is surrounded by complex Paleozoic‐Mesozoic fault systems. The field was discovered in 1984 by the Ministry of Geology and Mineral Resources, MGMR (now China National Star Petroleum Company, CNSPC). Later drilling confirmed a gas and condensate reservoir within the Lower Cretaceous Kapushaliang (K1Kp) Formation. Lesser volumes of hydrocarbons were found in the Jurassic and Lower Paleozoic strata. The top of the Lower Cretaceous reservoir is a simple, elongated, east‐northeast anticline (Figure 1). It is bounded to the south by a major reverse fault that is a part of the Luntai Fault system.

Mass transfer between eastern Tien Shan and adjacent basins (central Asia): constraints on regional tectonics and topography

SUMMARY Using depths and ages derived from isopachs, drill-holes or cross-sections, it is possible to reconstruct the space-time depositional history of a sedimentary basin. Drill holes and cross-sections give the local sedimentation history, while isopachs allow the definition of the spatial distribution of the sediments. Assuming several simple hypotheses, such as similarity of the strata and regional applicability of results derived from local analyses, one can reconstruct balanced maps of the solid (or grain) volumes, and hence the mass of sediments deposited during several time intervals since the Palaeogene. Applying this method to the Tarim and Dzungar basins (NW China), we estimate the total Cenozoic solid-phase volume and mass of sediments stored to be 1358 f 520 x lo3 km3 (36.7 f 14 x 1017 kg) and 172 f 56 x lo3 km3 (4.6 f 1.5 x 1017 kg) respectively. The reconstruction also enables us to detect two main pulses in the sedimentation. The first, around 17 Ma, affected only the northern part of the Tarim Basin (also known as the Kucha or Kuche Depression) at the foot of the Tien Shan Mountains and supports the idea that the presently active shortening regime in that range started at that time. The second, 5 to 6 Ma, affected most of the depositional areas of the region and may have an even greater geographical extent. Assuming local isostasy, we estimate the volume of shortening induced by the rotation of the Tarim block relative to Siberia and stored in the range and adjacent basins to be between 1.15 x lo6 and 4.23 x lo6 km3. This correspbnds to a clockwise rotation of between 2.5 and 8.7. We use these results in two simple models of self-similar growth of pyramidal topographies that approximately fit the eastern Tien Shan.