Reservoir formation geological features of large Sulige Gas Field in China

摘要

Sulige Gas field in Ordos Basin is the largest gas field in China offshore. At present, 600 billion cubic meters of reserves in Carboniferous-Permian have been proven since the beginning of systematic evaluation exploration in 2000. Sulige gas field is located in the central part of the basin which has favorable geological conditions for forming natural gas. Widely distributed source rock in Ordos Basin was deposited widely in the paralic environment during the Paleozoic. With the deepening and thermal evolution, organic matter has been mature or high-mature, providing abundant gas sources. The superimposed fluvial-delta sandstones which are distributed approximately from north to south, have constituted the complex sandstone reservoir body in a large area. Under the background of the gentle west-dip monocline, the fluvial-bay pelitic rocks to the east act as the barriers laterally, the various deposition face belt to north part as lithologic fight barrier, and the lacustrine pelitic rocks of the Upper Permian as a good regional seal, as a result, forming a large-area lithologic trap in Sulige area. The high content of quarts in continental fades, and the dissolution and erosion of volcanic matter are favorable for forming high-porosity and high-permeability reservoirs. The perfect timing of sources, reservoirs, seals, traps, and the condition of preservation provides a fundamental guarantee for forming and preserving the Sulige. gas field.