ANALYSIS OF THE ACCUMULATION MODEL OF THE SINIAN-CAMBRIAN IN THE EASTERN SICHUAN BASIN

Since the Sinian-Cambrian extra-large Anyue gas field was discovered in the Sichuan Basin, the deep layer of the high-steep tectonic belt in the eastern Sichuan Basin has become an important successor for the southwest oil and gas fields, and comprehensive research on oil accumulation is urgently needed. Based on the comprehensive analysis of old well review, the field outcrop and drilling data, the 3D seismic and the regional geological survey, the Z₂dn² , Z₂dn⁴ , ∈₁l and ∈2x Formation are four large-scale karst reservoirs. Through careful characterization and evaluation, it is believed that the mainly source rock is the ∈1q Formation, while the Z₂dn³ and Z₂dn² Formation are supplemented. and the relationship between source rocks, reservoirs and caprocks is considered to be superior.

In order to study the accumulation model, results of the brittle-plastic simulation experiment of the group were firstly extrapolated to the geological conditions, and matched with the real single-burial history. It was found that the best sealing ability of the salt rock is matched with the hydrocarbon generation peak. In addition, based on the physical simulation experiment technology and material template by hundreds of simulation experiments, the physical model of the eastern Sichuan Basin was established. The experimental results show that the salt rock underwent creep deformation during extrusion, and a thick salt rock mass was formed in the appropriate pressure pooling zone; the salt upper and lower sides formed two types of traps under the uncoordinated deformation, which is favorable for the exploration area.

Based on the results of comprehensive reservoir forming conditions, numerical simulation and physical simulation experiments, the accumulation model of the Sinian-Cambrian Formation in the eastern Sichuan Basin has been proposed. That is the oil-producing period of the lower part of the salt rock is relatively early, and the oil and gas mainly migrates to the upper part. After entering a large number of gas periods, the oil and gas gathers in the lower part of the source rock and laterally accumulates; the oil and gas inside the salt rock is mainly come from the lower part; the lower reservoirs of the salt rock are supplied by multiple sets of source rocks; The source rock can also be trapped inside.