The Parnaiba Basin is a Paleozoic to Mesozoic intraplate volcano-sedimentary basin where the Pimenteiras Formation (Devonian) is the main sequence with potential of hydrocarbon generation, mostly natural gas. The present paper evaluates the potential of hydrocarbon generation of Pimenteiras Formation based on Total Organic Carbon (TOC) and Rock-Eval pyrolysis parameters. In this work, 1077 shale samples of the Pimenteiras Formation distributed in 32 wells were evaluated. The TOC content varies between 0.1 to 4.7 wt.%, partially reflecting the accumulation and preservation rates of the organic matter in marine and coastal depositional environments controlled by regressive-transgressive cycles. The oxic and anoxic conditions vary significantly with deposition in this situation, which were evidenced by HI and OI variations through sample profiles. In the north and center of the basin, the Pimenteiras Formation has a higher potential for hydrocarbon generation relative to the south, probably due to higher anoxic conditions during deposition. The Hydrogen Index indicates the predominance of kerogen types II and III with minor occurrences of types I and IV. The Tmax values indicate general immature conditions and locally postmature, where the lowest temperatures represent the basin´s burial history, whereas the higher ones were influenced by igneous intrusions and thermogenic anomalies related to the Transbrasiliano Lineament. In addition, the excessive heat around the intrusions altered the Rock-Eval pyrolysis parameters as well as the type of organic matter, resulting in a relative increase of the kerogen types III and IV, which explains the great potential for gas generation in this basin.

帕尔奈巴盆地是一个古生代至中生代板内火山沉积盆地，其中Pimenteiras组（德文统）是具有生烃潜力（主要是天然气）的主要层序。本文基于总有机碳（TOC）和岩石-Eval热解参数评估了Pimenteiras组烃生成的潜力。在这项工作中，评估了分布在32口井中的1077个Pimenteiras组页岩样品。TOC含量在0.1至4.7 wt。％之间变化，部分反映了有机物在海洋和沿海沉积环境中的渐进-渐进循环控制下的积累和保存速率。在这种情况下，有氧和无氧条件会随沉积而显着变化，这通过样品曲线中的HI和OI变化来证明。在盆地的北部和中部，Pimenteiras组相对于南部具有更高的生烃潜力，这可能是由于沉积过程中较高的缺氧条件所致。氢指数表明，II型和III型干酪根占优势，I型和IV型发生率较小。Tmax值表示一般未成熟条件和局部过早成熟，其中最低温度代表该盆地的埋葬历史，而较高温度则受火成岩侵入和与Transbrasiliano Lineament相关的热成因的影响。此外，侵入岩周围的过热影响了岩石-Eval热解参数以及有机质的类型，从而导致了III型和IV型干酪根的相对增加，这解释了该盆地天然气的巨大潜力。