The emplacement of large intrusive complexes into sedimentary basins can have profound effects on host sedimentary rocks including deformation, thermal aureole metamorphic reactions, alteration of fluid-flow pathways, and the formation of associated hydrothermal vent complexes (HVCs). These processes can in turn have major implications for petroleum systems on the local and regional scale, and can contribute to global climate change due to the production and outgassing of greenhouse gases, such as CH 4 and CO 2 . Imaging these features and assessing their implications from seismic data beneath extrusive volcanic cover is challenging due to heterogeneities in the volcanic pile and at the basalt-sediment transition. We have evaluated combined field and laboratory petrophysical data from the Isle of Skye, Scotland, where we identify a seismic-scale example of extensive intrusions interacting with the base-basalt transition. We have also evaluated a unique onshore example of a linked sill and associated HVC cutting up through the lava sequence. We compare these field results with HVCs from reflection seismic data across the Vøring Marginal High, offshore Norway, where subbasalt saucer-shaped intrusions are also seen associated with HVCs cutting the lava sequence. Seismic imaging problems associated with the velocity heterogeneity of volcanic sequences, along with a historical lack of highquality 3D data in volcanic regions worldwide, is suggested as having largely precluded the identification of these features in the past. The under-representation of these hydrothermal vents in the literature has key implications for the future appraisal of intrusion-related outgassing effects on the global climate such as those related to the Palaeocene Eocene Thermal Maximum, along with subbasalt petroleum prospectivity where they may alter maturation and migration pathways.

Tangkuban Parahu Volcano is one of the most active volcanoes in West Java, Indonesia, although most of the recent eruptions were relatively mild (e.g. 2013 eruption). However, there is still little information from the volcanic products in the proximal area. Here, a new documentation from the proximal volcanic succession is provided, including tephra-stratigraphy, componentry analysis, and petrography of volcanic products. Detailed mapping of the proximal area shows that the volcanic products are predominantly composed of alternating fine-clay and coarse ash, lapilli tuff, and pyroclastic breccia within ten tephra units. Componentry of ash particles revealed the presence of five components, associated with hydrothermally altered lithics, oxidized lithics, coherent crystalline lithics, magmatic juvenile, and free crystal in entire eruptive products. These indicate that the subvolcanic hydrothermal system has been developed since the Holocene and associated with a continual introduction of magmatic intrusion. Petrographic observation shows the presence of hydrothermal minerals of quartz or silica accompanied by alunite and kaolinite, representing acidic alteration within the crater-conduit. The existence of a silicified zone indicates that the subvolcanic hydrothermal system played an essential role as a cap-rock of pressurized gas and steam at depth (200-500 m), whereas magmatic injection caused the vapour plume expansion. The observation concluded that the proximal volcanic succession captured the evidence of coupled phreatic and phreatomagmatic activities during the latest development of Mount Tangkuban Parahu.

A series of analyses techniques were performed to study the influence of different acid concentrations on the rock properties during the acidizing process. Based on the Thin section and Routine Core Analysis (RCA), the calcite content have effect on the reservoir quality from the aspect of rock-fluid properties. In this paper, the physical and mineralogical responses to rock acidizing of carbonate rock are evaluated. This study found that calcite content decreases approximately 25% from the total calcite content of rock samples after the addition of HCl. Scanning Electron Microscope (SEM) Analysis show that samples treated using HCl 15% provide a wider pore size distribution, resulting in the increasing permeability fluid flow rate

A subvolcanic-hydrothermal system involves complex interaction between magma, magmatic fluids, and hydrothermal system at stratovolcanoes in subduction setting. These interactions are responsible for magmatic-hydrothermal eruption associated with rapid injection of magmatic gas into hydrothermal system at a certain depth of volcanic edifice. However, capturing these interactions is challenging due to inaccessibility to the crater conduit within the edifice. Therefore, we selected a method to analyze the volcanic products from several episodic phreatic and phreatomagmatic eruptions during the Holocene at Tangkuban Parahu, Indonesia. In this context, Holocene volcanic products are one of the best examples to understand an interplay between magma, magmatic fluids, and hydrothermal system in producing violent eruptions. In this study, we carried out petrological and sulfur isotope analysis only for the hydrothermally altered lithic ash particles, a part of proximal volcanic products. Mineral assemblages mostly exhibit a typical acid-sulfate and advanced argillic alteration, consisting of alunite, kaolinite, and silica minerals. Acid-sulfate and advanced argillic alteration indicates that those mineral assemblages were formed under the formation temperature ranging from ~100 to ~260 . The calculated temperature from sulfur isotopic fractionation of sulfate-sulfide shows 230-240 , which is almost identical with assigned temperature from mineral assemblages. Sulfur isotope and jarosite occurrence indicate the supergene alteration associated with oxygen entrainment to the hydrothermal system that oxidize pyrite to jarosite. Sulfur isotopic variation throughout the studied stratigraphy represents influx of magmatic gas to the hydrothermal system. Moreover, zoned P-bearing alunite represents repetitive injection of magmatic gas to the active acidic hydrothermal system, which also indicates the magmatic-hydrothermal interaction below the crater. Occurrence of enargite and chalcopyrite represents the nature of upper-level high sulfidation system at shallow volcanic edifice of the Tangkuban Parahu volcano. Furthermore, we showed that coupled petrological and sulfur isotope analysis has paramount importance to evaluate the conditions of the subvolcanic hydrothermal system, magmatic-hydrothermal interaction, and the origin of steam-blast eruptions at volcanoes that contain subvolcanic-hydrothermal systems.

Mangkalihat peninsula is located between Kutai and Tarakan basins, which known as two Hydro Carbon (HC) Prolific basins in Eastern Borneo. The petroleoum system in this area is poorly known because of the different system between Kutai and Tarakan Basin. The field study is focusing in the eastern part of Mangkalihat Peninsula, where The Tabalar and Tendehantu Formation are exposed. The data compilation is from outcrop, thin section and plug sample which permeability and porosity values were measured by Klickenberg method. Outcrop analysis showed that Tendehantu Formation can be divided into two lithofacies, whileTabalar Formation has only one lithofacies. The petrographic thin section analysis showed three microfacies from the two formations. Pore destruction caused by diagenesis can de indicated with the presence of bladed and equant cement in vuggy pores, while the diagenetical development of porosity is marked by the microfracturing that was assumed to be formed by compaction and deep burial and matrix dissolution in some of the samples. Petrography and plug sample data integration shows the quality value of those carbonate rock as a reservoir from the permeability and porosity parameter. Based on the microfacies grouping showed in three microfacies, the porosity value is 5.26 - 17.32 % (tight to good), and permeability value is 0.041 – 7.27mD (fair – poor). The carbonate rock quality is influenced by the whole diagenetic processes that happened in each lithofacies.