Formation Mechanisms of Paleogene Igneous Rock Plays in Huimin Sag, Eastern China

Abstract

In order to understand the impact of volcanism and intrusion on the source rocks, how the pores and fissures formed and how the hydrocarbon was trapped, this study focuses on the formation mechanisms of the igneous rock plays in the Huimin Sag based on geochemical and lithological analyses and typical anatomy. The results indicate that volcanism enhanced the formation of Es 3 source rocks with high TOC (3.41-5.12%) in the distribution areas of igneous rocks. Volcanism caused an abnormal heat field and accelerated the maturation of hydrocarbon source rocks, leading to a higher heat gradient (3.4-4.4 °C /100 m), increase of HC and chloroform bitumen "A" contents, earlier hydrocarbon generation threshold and higher biomarker maturity closer to the igneous rocks. The primary fractures, vesicular structures, inter-breccia pores, intergranular pores, intercrystal and intracrystal pores are primarily-formed. The structural fractures and corrosion space are secondarily formed. Rising fluid pressure associated with volcanism accelerated the hydrocarbons expulsion. Igneous body can act as a migration pathway or a seal constrained by its physical property. Volcanism in the Huimin Sag produces diaper arch trap, overlap trap in volcano slope and drape anticline trap on the volcanic cone. Five models for igneous rocks plays in the Huimin Sag, such as volcaniclastic play with outside source rocks, diabase plays with interior and exterior source rocks, basalt plays with exterior and mixed source rocks are proposed.

Geochemical characterization and possible hydrocarbon contribution of the Carboniferous interval natively developed in the Chepaizi Uplift of Junggar Basin, northwestern China

“…Note that T max values do not change significantly at late stage of thermal evaluation (Peters et al, 2005;Chang et al, 2011). So the measured %Ro values are believed to have high credibility as a marker of maturity (Peters et al, 2005).…”

Geochemical characteristics and origin of hydrocarbons in the Mesoproterozoic reservoirs in the Liaoxi Depression, NE China

“…Potential source rock samples were crushed to 80 mesh. 100 mg powdered rocks for each sample were selected for TOC and Rock-Eval pyrolysis analysis using a LECO CS-230 Carbon Analyser and an OGE-II Rock Pyrolyser, respectively (Chang et al., 2011).…”

Influence on the oil‐gas accumulation potential of the laminated algal micritic dolomite in Jixian system from Mesozoic magmatic activities at the south‐western margin of the Ordos Basin, China

“…Magmatic intrusion would inevitably affect the physical properties of surrounding rock, which would alter the porosity, permeability, and rock density accordingly (Chang, Han, Li, Yang, & Chen, 2011;Li et al, 2016;Liu, Xie, Wang, Cui, & Zhang, 2015;Liu, Teng, et al, 2016;Shao et al, 2015;Wyering et al, 2014). The results of physical properties of the dolomite samples are presented in Table 4.…”

“…Thermal effect in the massive magmatic intrusion activities would cause the regional thermal anomaly, which would have some influence on the thermal evolution of organic matter (Aghaei et al, ; Chang et al, ; Wang, Ma, Han, Wang, & Dong, ). As illustrated in Figure , with increasing distance from the intrusion, the parameters have a weakening trend and most parameters have an obvious change at about 15 m, including adsorbed hydrocarbon ( S 1 ), pyrolysis hydrocarbon ( S 2 ), hydrocarbon generating potential ( S 1 + S 2 ), and T max.…”