Tarim Basin, NW China: Hunting Elephants

Xu, Tianguang¹, Dengfa He² (1) IHS Energy, Houston, TX (2) Research Institute of Petroleum Exploration and Development, PetroChina, Beijing, China

The Tarim Basin, with an area of 560,000 sq km in western China, is known for its complex geology and remoteness. 87 fields/discoveries have been made in the basin, with total reserves of 4,425 MMbo and 30.8 Tcfg. The basin has been estimated to hold petroleum resources of 78,548 MMbo and 296,293 Tcfg. Thus, the future exploration potential is significant. In order to facilitate exploration, PetroChina is planning to open nine blocks to international oil companies in this resource-rich basin.

The Tarim basin experienced Paleozoic craton, Mesozoic rifting, and Cenozoic foreland thrust-faulting tectonic phases. These complex multicycle tectonic regimes led to the development of multiple source-reservoir-seal associations spatially and temporally. Source rocks consist of marine carbonates of the Cambrian and Ordovician, mudstones and carbonates of Permo-Carboniferous, and lacustrine mudstones and coals of Triassic-Jurassic. Reservoirs are dominated by carbonates of Ordovician and Carboniferous and sands of Carboniferous, Triassic, Cretaceous, and Tertiary.

Before 2000, anticline-dominated structural plays were predominately recognized. Since 2000, however, both stratigraphic and structural plays have been delineated with improved seismic acquisition and processing, especially in desert and mountain front areas. Geochemical and geological analyses recognized seven known and three speculative petroleum systems in the basin. Fields in the basin are typically charged by either a single or multiple petroleum systems.

Petroleum systems and play analyses indicate that the most favorable plays are those on the paleo-uplifts, charged by Paleozoic marine source kitchens, and on the foreland thrust belts, charged by Mesozoic lacustrine mudstone and coal source pods.