Shiyou shiyan dizhi (Jul 2023)
Hydrocarbon generation and evolution characteristics of Carboniferous source rocks on the northeastern margin of the Junggar Basin and its petroleum geological significance
Abstract
Various types of source rocks were developed in the Carboniferous trench-arc basin environment on the northeastern margin of the Junggar Basin. In order to implement the efficient hydrocarbon supply area of the main source rocks and guide the oil and gas exploration in this area, researches on the hydrocarbon generation mechanism, potential, evolution process, and hydrocarbon supply characteristics of different types of source rocks were carried out through the combination of geology and geochemistry based on the test data of drilling, organic geochemistry of outcrop source rock samples, and hydrocarbon-generating thermal simulation experiments. The results show that there are three types of source rocks, namely mudstone, tuffaceous mudstone and carbonaceous mudstone in the Carboniferous in the study area. Different source rocks have different parent material composition and activation energy distribution for hydrocarbon generation, and their hydrocarbon generation potential and evolution model have obvious differences. Mudstone generated hydrocarbon rapidly at relatively low maturity stage, tuffaceous mudstone continued to generate hydrocarbon slowly, and carbonaceous mudstone generated hydrocarbon rapidly at relatively higher maturity stage. Later structural transformation, sedimentary filling and geothermal field evolution jointly controlled the thermal evolution process and hydrocarbon supply characteristics of source rocks. Hydrocarbon generation and hydrocarbon loss of source rocks were coupled in time and space, and six hydrocarbon supply models can be divided, i.e., (1) high-efficiency hydrocarbon generation, low hydrocarbon loss, high-efficiency hydrocarbon supply, (2) high-efficiency hydrocarbon generation, relatively high hydrocarbon loss, relatively high-efficiency hydrocarbon supply, (3) relatively high-efficiency hydrocarbon generation, low hydrocarbon loss, relatively high-efficiency hydrocarbon supply, (4) relatively high-efficiency hydrocarbon generation, high hydrocarbon loss, low-efficiency hydrocarbon supply, (5) low-efficiency hydrocarbon generation, high hydrocarbon loss, relatively low-efficiency hydrocarbon supply, and (6) low-efficiency hydrocarbon generation, low hydrocarbon loss, low-efficiency hydrocarbon supply. Among them, the Shibei and Dishuiquan sags are relatively high-efficiency hydrocarbon generation, low hydrocarbon loss and relatively high-efficiency hydrocarbon supply units with material foundation for forming large and medium-sized oil and gas fields, which are the most favorable exploration targets at present.
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