Diagenesis Study of Jatiluhur Formation at Cipamingkis River, Bogor Regency, West Java, Indonesia

Abstract

Diagenesis studies in the Jatiluhur Formation are still relatively new, especially in the Cipamingkis River. This research can provide information in the form of components and characteristics of sandstone in the Jatiluhur Formation which can be used as a basis for further research or useful information in the oil and gas industry. Knowledge of diagenetic could be one of the factors that affect in raservoir quality, espesially in sandstone. In this study, data collection was carried out through surface mapping, which is 55 rock samples were obtained from stratigraphic measuring section with a path length of ±2 Km in the Cipamingkis River. The data is in the form of information on sedimentarry structure, textures and composition. There were 23 sandstone and 2 limestone samples which were then subjected to petrographic analysis, X-ray diffraction (XRD) and scanning electron microscopy (SEM). The results of study are several features of diagenesis were found including compaction that works in the form of point contact, long contact, concavo-convex contact and suture contact and dominated by mechanical compaction, while in limestone there is a brittle fracture feature in bioclasts. The cement found in the form of calcite cement, quartz and clay minerals that the form of kaolinite, smectite and illite, while the limestone is in the form of blocky and fibrous to bleded which is filled with calcite minerals. Dissolution occurs in the minerals of quartz, feldspar, and mica. The mineral replacement that is commonly found occurs in quartz and feldspar minerals. In limestone, there is an intergranular micritization. The dominant type of porosity found was interparticle with an average of 10.4% found between 3 – 23%. The history of diagenesis that occurs in rocks in the Jatiluhur Formation begins with the initial deposition of eogenesis, followed by burial mesogenesis and ends with telogenesis which reveals rocks on the surface.