Mesozoic limestone units of the Woyla group were identified in many places across the northern part of Sumatra, Indonesia. Even though these sedimentary rocks may play an important role as an element of the potential Pre-Tertiary hydrocarbon play of Sumatra, their characteristics are still not well understood. This study tries to fill this research gap and aims to better understand the characteristics of the limestone members of the Woyla group. There are three objectives of this study: (1) to characterise structural features, and deformation of the Woyla Group; (2) to provide sedimentary characteristics of the limestone members of the Woyla Group; and (3) to understand the main influences on the development of the limestone members of the Woyla Group. An integrated geological analyses, including structural scanline analysis, petrographic analysis, and acid digestion analysis, was conducted to achieve the objectives of this study. Findings from this research show that the limestone members of the Woyla group were strongly deformed, and structural features such as bedded strata, faults, folds, and joints were identified within these rocks. The limestone units of the Woyla group consist of at least six microfacies. These are wackestone, packstone, wackestone-packstone, packstone-rudstone, fossiliferous sandstone, and fossiliferous shale. Depositional processes, sea level fluctuations, tectonisms, and climatic variations are interpreted as the main factors influencing the development and evolution of these limestone units. It is expected that the results of this study could advance our understanding of the Pre-Tertiary carbonate rocks in general, and the Woyla group of Sumatra in particular.

This ongoing research evaluates a fractured carbonate reservoir in the Beekeeper Formation, Perth Basin, focused mainly on the Woodada Field. Previous reports identified a fractured carbonate system as the main hydrocarbon reservoir in the Woodada Field, yet there is no published detailed documentation of reservoir development. The aim of this research is to evaluate the depositional and diagenetic characteristics of the Beekeeper Formation, its fracture system development and their combined impacts on carbonate reservoir quality. This study employs multi-method geological analyses. Subsurface core description, standard microscopy, and acetate peel analyses have been conducted, while scanning electron microscopy, cathodoluminescence petrography, stable isotope geochemistry and fluid inclusion analyses are planned for the coming months. Preliminary results show that the carbonate of the Beekeeper Formation consists of packstone, rudstone, packstone-rudstone, floatstone-packstone and packstone-grainstone. The development of the Beekeeper Formation was affected by tectonic activity. The level of influence of tectonic processes, versus diagenesis and primary sedimentary facies on the development of fracture systems, pore system generation and reservoir quality is still being studied in detail. It is anticipated that this ongoing study will increase our understanding of the Woodada Gas Field and fractured carbonate plays in general.

The heterogeneities of mixed carbonate-siliciclastic reservoirs are not well understood, despite the importance of this type of deposit as a proven hydrocarbon reservoir in many oil and gas fields. This study aims to advance our understanding of the heterogeneities of the mixed carbonate-siliciclastic reservoir with three main objectives: (1) to characterize sedimentary facies and depositional environment of the Beekeeper Formation; (2) to better understand the mixing of siliciclastic and carbonate materials; and (3) to better understand the main influences on the development of a mixed carbonate-siliciclastic reservoir. Integrated geological analyses (sedimentary logging, acetate peels, acid digestion, and petrographic) have been conducted to achieve the aim and objectives of this study. Results show that the Beekeeper Formation consists of seventeen facies grouped into carbonate-dominated facies group, siliciclastic-dominated facies group, and mixed carbonate-siliciclastic facies group, and was deposited within a ramp type platform. Both compositional and stratal mixing were identified as present within the Beekeeper Formation. The mixing of carbonate and siliciclastic materials/minerals within this formation occurred at three different scales, which are small scale (mm to cm scale), moderate scale (cm to a few m scale), and large scale (a few m to >100 m scale). The presence of fracture systems, highly varied facies, and the mixing of carbonate and siliciclastic materials/minerals are evident in the evolution of the Beekeeper Formation which was strongly influenced by tectonic activities, climatic conditions, eustasy, sea-level fluctuations, rate of carbonate production, and terrigenous influx.

Lake Lut Tawar, which is situated in Aceh Tengah, has a unique geological landscape, with the presence of rock formations of the Pre-Tertiary age (Tawar Formation) and its geological connection with the Sumatran fault and the Bukit Barisan mountains. Even though the geological condition of the Lut Tawar Lake has attracted the attention of many geologists to carry out various kinds of research, there is still a lot of geological understanding that is not yet known, especially regarding the Tawar Formation. Tawar Formation is of Pre-Tertiary age and can be found around Lut Tawar Lake, Aceh Tengah. This research targeted the Tawar Formation with two main objectives: (1) to evaluate structural deformation and geologic structures developed within the Tawar Formation and (2) to understand better the main factors influencing the evolution of the Tawar Formation. Integrated geological analyses, including structural geology analysis, scanline method, and stereo net method, were used to achieve the objectives of this research. Results from this study show that the Tawar Formation has experienced a complex structural deformation, evidenced by the presence of various geological structures such as multi-size and multi-episode fracture systems and numerous folds and faults. Furthermore, we interpret the evolution of the Tawar Formation to be strongly influenced by tectonic activity, possibly related to the movement of the Sibumasu plate, the Sumatran fault system, and plate subduction in the southwest part of Sumatra. It is expected that the results of this research will provide a new understanding of the history and evolution of the Tawar Formation and a better understanding of the deformation of rock structures that occurred in the Lut Tawar area, Aceh Tengah.

Seulawah volcano, located in Sumatra, Indonesia, is renowned for its geothermal potential, a crucial source of cleaner energy for Indonesia’s future growth and security. Available studies of Seulawah volcano primarily focus on its general geological, geochemical, and regional characteristics, with limited research on its shallow subsurface conditions. This study aimed to fill this research gap and enhance our understanding of the geothermal system of Seulawah volcano. There are two objectives of this study: (1) to conduct a transient electromagnetic (TEM) survey across the study area and (2) to better visualize and characterize the shallow subsurface conditions of the geothermal system of Seulawah volcano. The TEM method, which employed 60 stations (with distances between stations ranging from 0.5 to 1 km) and intersected several geothermal manifestations as well as local and regional faults, was used to achieve the objectives of this study. The Occam algorithm was applied for 1D inversion of TEM data, which was then validated using magnetotelluric data. The results of this study indicate that the geothermal system of Seulawah volcano has the potential to generate up to 230 Mwe of electrical energy. Moreover, the shallow depth (10 Ωm. At a depth of 500 m, a conductive layer with resistivity values <10 Ωm was observed, interpreted as a clay cap where fluids from the reservoir layer accumulate. Validation with magnetotelluric data shows results consistent with the TEM data, confirming that the findings of this study are reliable. These findings contribute to a deeper understanding of the geothermal system of Seulawah volcano and are expected to support the development of greener, renewable energy sources for Indonesia.

Ilmu geologi mempunyai peranan penting dalam berbagai lingkup kehidupan masyarakat termasuk dalam hal eksplorasi dan eksploitasi sumberdaya alam (minyak dan gas bumi, mineral, batubara), dan juga dalam hal mitigasi bencana alam kebumian (gempa bumi, tsunami, gunung meletus). Disamping itu, pengetahuan geologi juga berguna untuk keperluan kegiatan dakwah islamiyah. Berbagai macam fenomena geologi tertulis di dalam Al-Qur’an, namun banyak sekali para pendakwah (da’i) yang masih belum mampu menjelaskan hal tersebut secara keilmuan ilmiah. Untuk mengatasi permasalahan tersebut, maka dirasa perlu untuk diadakan kegiatan pengabdian ini. Materi keilmuan geologi yang diajarkan dalam kegiatan ini dikombinasikan dengan pemahaman keilmuan islamiyah untuk menjelaskan fenomena alam yang tercantum dalam Al-Qur’an. Kegiatan pengabdian ini memberikan manfaat yang cukup besar terutama untuk para peserta yang telah ikut berpartisipasi. Diantara dampak langsung yang dirasakan oleh para peserta yaitu adanya peningkatan wawasan, dan pengetahuan dasar geologi serta adanya peningkatan kompetensi para peserta dalam mengaitkan pemahaman keagamaan dengan keilmuan geologi dalam rangka pelaksanaan dakwah islamiyah. Dengan adanya kegiatan pengabdian masyarakat ini, diharapkan peningkatan kompetensi para peserta bisa digunakan semaksimal mungkin dalam melakukan kegiatan dakwah islamiyah. Kata kunci: Fenomena Geologi, Al-Qur’an, Keilmuan Geologi. ABSTRACT Geology plays an important role in various spheres of human life, including in the exploration and exploitation of natural resources (oil and gas, minerals, coal), and also in the mitigation of natural disasters (earthquakes, tsunamis, mountain eruptions). Besides, geological knowledge is also useful for the purposes of Islamic activities. Geological phenomena are written in the Al-Qur’an, but many preachers are still unable to explain these scientifically. In order to solve this problem, it is considered necessary to hold training in the application of geological science to support the activities of Islamic teaching. The geological materials taught in this activity was combined with the understanding of Islamic science to explain some of the natural phenomena listed in the Al-Qur’an. This activity has been very beneficial, and among the direct impact felt by the participants is the improvement of insight, and basic knowledge of geology as well as the increased competence of the participants in linking the understanding of religion with geological science in the implementation of Islamic teaching. With this activity, it is expected that the increased competence of the participants can be used as much as possible in carrying out Islamic activities. Keywords: Geological Phenomena, Al-Qur’an, Geological Science.