Influence of Carboniferous–Permian magmatic activities on thermal evolution of hydrocarbon source rocks in Tarim Basin

This paper is the result of oil and gas exploration engineering.

Objective The formation temperature history is a pivotal determinant in the maturity evolution of organic matter and the hydrocarbon generation and expulsion process within hydrocarbon source rocks. This history is shaped not only by the evolution of basin heat flow and the sedimentary and burial processes but also significantly influenced by anomalous heat events, such as magmatic activity, which must be considered. Investigating these factors is crucial for a comprehensive understanding of the organic matter maturation process.

Methods This study leverages the exploration and development insights from the Tarim Oilfield to examine the impact of magmatic intrusions on formation temperature and the thermal evolution of hydrocarbon source rocks. We employ numerical simulation and drilling data to discuss these influences and calculate the spatial and temporal extent and intensity of the intrusions.

Results Based on measured vitrinite reflectance data (Ro) from several wells in the Carboniferous–Permian strata of the central and western Tarim Basin, reveal abnormally high values associated with igneous rocks. These high values are indicative of magmatic activity during the late Carboniferous–Permian period. Thermal history modeling of the wells indicates that magmatic activity heated the Paleozoic hydrocarbon source rocks, accelerating the thermal evolution and maturity of the organic matter, leading to a swift transition into the high−over−maturation stage.

Conclusions Anomalous magmatic thermal events play a beneficial role in enhancing the hydrocarbon generation intensity of hydrocarbon source rocks, achieving the highest relative hydrocarbon production rates, and facilitating the rapid maturation of organic matter.