Jambi Sub-Basin Research Articles

Provenance and Petrographic Analysis of Paleogene Sandstones in the Bukit Tigapuluh Area, Jambi Subbasin, Indonesia

The study investigates the provenance of Paleogene sandstone deposits from the Lemat Formation in the Lubuk Lawas and Lubuk Bernai sections of the Bukit Tigapuluh area, Jambi Subbasin, South Sumatra Basin, Indonesia. The research aims to elucidate the formation history and stratigraphic evolution of these sedimentary rocks through detailed petrographic analysis. Twenty-two rock samples were analyzed to classify the sandstones and determine their source rock types and tectonic settings. The results indicate that the sandstones are primarily classified as Lithic Arkose, Arkosic Subarkose, Feldspathic Litharenite, Silty Claystone, Sublitharenite, and Subarkosic Wacke. The provenance analysis suggests that these sandstones originated from a tectonic setting of a recycled orogenic zone, comprising quartzose recycled, transitional recycled, and mixed sources, indicating a combination of primary and recycled orogenic materials. Paleocurrent analysis from sedimentary structures in the Lubuk Bernai area suggests deposition directions from the southwest and southeast. This study provides significant insights into the paleogeography and tectonic evolution of the Lemat Formation within the Jambi Subbasin. Further research should focus on integrating geochemical data to refine the understanding of sedimentary provenance and tectonic implications.

Seismic Analysis of RMS Amplitude Attributes to Identify Hydrocarbon Potential in Field "X" of Jambi Province Indonesia

Indonesia has many potential oil and gas basins. Seismic attribute analysis of RMS Amplitude (Root Mean Square) was conducted in the Betung area, Jambi sub-basin, South Sumatra Basin. The reservoir characterisation technique used in this study is rms attribute analysis which can show changes in the lithology of the study layer. Seismic attributes were extracted from 2D pre-stack time migration (PSTM) seismic data. This study also takes BTJ-210 log data as interpretation and determines the reservoir thickness at the target. Based on the seismic attribute analysis with rms, it is verified that the reservoir is indeed detected within the analysis window of 10 ms, 20 ms, 30 ms, 40 ms and the possible distribution of the reservoir is in horizon 3 and horizon 4 which has a high range of amplitude values and is in a high range zone or higher area than the surrounding area. The results of this seismic attribute analysis can show the hydrocarbon prospect zone and the potential for new well development in the study area, which is located in Horizon 3 and Horizon 4 at a depth of 227 to 250 metres south of the study area.

ANALISIS JENIS FLUIDA RESERVOIR BERDASARKAN NILAI SW DAN LOG SUMUR DS-19, CS-21, RS-23 FORMASI AIR BENAKAT CEKUNGAN SUMATERA SELATAN

Hydrocarbon exploration currently has a variety of methods in operation to determine and identify a reservoir according to the required parameters. Well log data plays an important role in the development of hydrocarbon exploration. Hydrocarbon saturation can be known by first calculating the water saturation, so the value of Sw is the key to work to determine the type of reservoir and its fluid content at an interval or reservoir zone accompanied by crossover and separation readings on the density & neutron log curve. The research was conducted in the Jambi Sub-basin area, ANONIM field, South Sumatra, DS-19, CS-21, RS-23 wells with shaly sand lithology which produces three productive zones. Based on the results, wells DS-19, CS-21, RS-23 has a gaseous hydrocarbon fluid with Sw value in the DS-19 well of 10.5%, CS-21 well of 27.1%, and RS-23 well of 22.4%.

Pore Pressure Estimation Using Bowers Methods in Shale Gas Reservoir Jambi Sub-Basin

Pore pressure prediction has important implications in determining the success of a drilling activity. Information of subsurface pore pressure prediction in hydrocarbon exploration and production is very important. For geologist this information can be used to determine of hydrocarbon generation and maturation within a basin, while for petroleum engineer pore pressure prediction is very important to maintain the production rate and for drilling engineer this information is useful for mud weigh and casing designs prior drilling activities to prevent blow out. This study is conducted in the well A and B, Field "X", Jambi Sub-Basin. Wells A and B have problems when drilling operations are carried out, such as blow out and pipe sticking which causes high non-productive time (NPT). So, optimum pore pressure prediction analysis must be carried out to avoid downhole problems in the implementation of further development well drilling. First, this study identifies the mechanism of overpressure formation, then predicts pore pressure using the Bowers method and subsequently performs modeling of subsurface 3D pore pressure. The results of the analysis showed that overpressure occurred in the Gumai and Talang Akar Formations, overpressure mechanism in the formation was caused by compaction, fluid expansion (kerogen maturation), and based on analysis of 3D pore pressure modeling many overpressure zones were found in the Gumai Formation, Jambi Sub-Basin

Parameter Correlation of Proximate Analysis and Ultimate Analysis of the Calorific Value of Coal

Jambi Province is an area that has abundant coal potential, this is due to its location in the Jambi Sub-basin, part of the South Sumatra Basin. As one of the coal mining companies in Jambi Province, PT Kamalindo Sompurna conducts mining with the aim of being marketed and directly sold to predetermined consumers. If coal is tested for chemical properties in the form of proximate and ultimate analysis in a sustainable manner and correlated with its calorific value, the company can market or utilize coal directly or indirectly. Coal samples were taken by channel sampling method in the same seam, the number of samples obtained was 48 samples per 5 cm interval. The number of samples is then reduced to 5 samples with the composite method based on certain intervals. The caloric value of coal in the research area ranges from 4300 - 5300 cal / gr, the caloric value is correlated with the results of proximate and ultimate analysis using simple linear regression statistics. The results obtained between the 9 analysis parameters based on this correlation indicate that the levels of flying matter, ash, carbon content and oxygen levels have a strong correlation as indicated by the correlation value in sequence is 0.98; -0.93; 0.88; -0.89. After conducting a study based on these parameters and correlation values, researchers can provide references related to the use of coal in processing and its use as fuel, both in the power generation industry and processing of cement raw materials and so on.

Artificial intelligence approach to depositional facies characterization based on electrical log data

This research aims to determine the depositional facies from electrical log data using the gradient boosting classifier method, which comprises a powerful algorithm. The electrical logs used are gamma-ray (GR), resistivity (ILD), neutron porosity (NPHI), and density (RHOB), while the output is in the form of images. The training data consists of 4 wells in Jambi sub-Basin, South Sumatera Basin, while the testing data comprises 5 wells with gamma-ray, resistivity, NPHI, and RHOB as input. Several scenarios are used to predict the facies model, namely training and validation dataset by using and isolating facies in well combination input, and with or without feature augmentation. Furthermore, the values collected were validated using F1 score. The result showed that 85.5% and 84.7% of F1 scores were allocated to training and validation to increase accuracy in scenarios without facies isolation and with feature augmentation. Therefore, the gradient boosting classifier method is reliable enough to characterize depositional facies in the associated area of interest.

Integrated Pore Pressure Model Estimation – Case Study of Jambi Sub-basin, South Sumatera, Indonesia

Pore pressure estimation is crucial in drilling wells for safety purposes also a very effective method for dealing with drilling accidents. Determination of overpressure is the main foundation in the evaluation to minimize the non-productive time (NPT). Here we present several models to generate pore pressure analysis of well from Jambi Sub-basin, South Sumatera, Indonesia. The model for estimation pore pressure is carried out by 3 methods: Eaton, Yan & Han, and Kan & Swan. Those methods will be compared to gain a more accurate model estimation within the study area. Kan and Swan’s model show the best fit for estimation because this method is suitable for the formation of tester like MDT/DST on higher frequency with parameter of C1 = 0.001 and C2 = 0.0003 for Jambi Sub-basin. The velocity data to construct the 3D pore pressure model was also validated with well data using multi-attribute analysis. The multi-attribute analysis used 2 algorithms, namely step-wise regression and probabilistic neural network (PNN). The analysis show that PNN has a better correlation compared to step-wise regression. The analysis shows the overpressure zone depth is ranges from 1700 – 2000m on Gumai Formation with maximum pressure around 6500 psi. The peak of overpressure dominated by Gumai and Talang Akar formation is caused by the loading mechanism because the rate of sedimentation on thick shale sequence is higher than the rate of dewatering on those formations.

Shale Plays Characterization of the Talang Akar Formation in the Jambi Sub-Basin, South Sumatra Basin

The Jambi Sub-Basin is part of the prolifi c South Sumatra Basin which has been proven to produce conventional oil and gas in large quantities. In the basin, Talang Akar Formation (TAF) is believed to be the dominant source rock for commercial hydrocarbons. That means the TAF has potential as shale play resulting oil and gas. Generally, shale plays of the TAF was deposited on littoral-neritic environment during late period of syn-rift until early post-rift at Late Oligocene - Early Miocene. Based on well log analysis, identifi cation characters shale plays of the TAF in the Jambi Sub-Basin have good character as source rock reservoir. Several wells showed that early maturity level happened at depth less than 2000m. Most of TOC, S2 and HI values exist in the range of (1-10) wt%, (0.25 - 10) mg/g rock and (50 - 400) mg HC/ g TOC respectively. Shale plays of the TAF tend to have Type II, II / III and III kerogen. Most of existing wells are not located in the basin center. The geophysical methods such as seismic inversion and seismic attribute can be applied to predict the TOC (Total Organic Carbon) and brittleness index (BI) distributions especially in the basin center. Geologically, the shale plays quality in center of basin was interpreted better than the fl ank. Age of the shale in the Jambi Sub-Basin is relatively much younger when compared to shale in North America. This fact is suspected to cause the TAF shale play to be relatively less brittle. The data processing result shows that the brittleness index values of shale plays tend to be in the range of 40% - 70%.

Geochemical and Geomechanical Study on Gumai and Talangakar Formation to Determine Potential of Shale Gas in Jambi Sub-Basin, South Sumatra Basin

Jambi sub-basin, which is located in South Sumatra, Indonesia has enormous potential of shale gas play. Yet, detailed geological studies are rarely undertaken to understand this relatively new hydrocarbon play concept. This paper presents a combination of geochemical and geomechanical studies with the aim to better understand: (1) the maturity level of source rock; (2) the mechanical properties of shale; and (3) the quality of hydrocarbon source rock. This research began with determination of wells that penetrate the Talangakar and Gumai Formations that have shale in it. Source rock analysis was done by using TOC (total organic carbon), S1, S2, S3, Tmax, and Ro (vitrinite reflectance) data. Geomechanical evaluation was done by using XRD and well logs data. Brittleness index was obtained by using Jarvie et al. (2007) formula, based on the XRD data. S-wave and P-wave are used to calculate the rock strength, Young's modulus and Poisson's ratio with UCS-To methods.Source rock in the Geragai belongs to the of moderate-to-good category because it has more than 0.5% TOC and potentially forms gas because it has a type III kerogen. JTBS-2 well is the only well in the Geragai area which already mature and has been able to produce hydrocarbons, because it passed the oil and gas windows. Source rock in the Betara belongs to moderate-to-good category because it has more than 0.5% TOC potentially forms gas because it has a type III kerogen. Most formations in the Betara are not yet mature based on the value of Ro and Tmax. In wells that have not reached the oil window nor gas windows, the prediction line drawn on the Petroleum Source Rock Summary chart, estimated that they would pass the gas window at Lower Talangakar Formation or Lahat Formation at depth of more than 8000 feet. The results of XRD analysis showed that the Betara had a high brittleness index with an average of 0.809. Talangakar Formation has a higher rock strength values than Gumai Formation, both in Betara high and Geragai deep. The principle that say the rocks which have high TOC values will have a high value of BI can be proven in the study area, the rocks that have high Ro will have a high value of BI, cannot be identified in the study area. With sufficient high value of rock strength and low abundance of clay minerals, the rocks at Talangakar Formation is good for hydraulic stimulation.

Integrated Geological and Geophysical Approach to Reservoir Modeling: Case Study of Jambi Sub-basin, Sumatra, Indonesia

Abstract Integrated geological and geophysical investigations were successfully performed for reservoir modeling in an oil field in the Jambi Province sub-basin, Sumatra, Indonesia. The objective of this study is to characterize the oil reservoir in terms of its petrophysical properties using a facies model that is based on an integrated geological and geophysical approach. The reservoir target of this study is located in the Air Benakat Formation, which is identified with a thickness of 3 to 20 m and is deposited in a depth range of 1300–1500 m. The reservoir modeling of Air Benakat Formation is carried out to open a new discovery for this field, since the comprehensive reservoir modeling has not been intensively performed. Structurally, the reservoir is segmented into three compartments by four main faults, and stratigraphic investigations revealed three prospect layers. In the present framework of the depositional environment, assessments of well log data included formation evaluations, well log data correlations and sequence stratigraphy, were performed to produce high-resolution features of vertical and lateral distributions. In addition, seismic data were interpreted to guide the structural model, and to effectively construct a three-dimensional (3D) geological framework of reservoir properties. The modeled reservoir shows that the reservoir is primarily considered a transition zone to a shallow marine deposit, which is specifically located in a submarine fan channel with a plain/moderately steep angle of its sedimentation base. Depositional environments are generally characterized by the potential paleocurrent direction within the channel axis from NE to SW, with respective agreement from larger scale porosity and net/gross models.

SHALE GAS SWEET SPOT POTENTIAL OF TUNGKAL GRABEN, JAMBI SUB-BASIN SOUTH SUMATERA BASIN

The Tungkal Graben is located in Jambi Sub-basin, the northern part of South Sumatera Basin. This basin is known as one of the largest hydrocarbons producing basin in Indonesia. There are several proven source rocks in the South Sumatera Basin. The paralic shales and coal horizon of Talangakar Formation (TAF) are known as primary source rock in this basin and considered as a reservoir of shale gas-bearing in Tungkal Graben Area as well. This study used surface geological data that was collected from the southern foot of Tiga Puluh Mountain as the outcrop analogy and subsurface data (existing well and seismic data) in Tungkal Graben Area. This study applied integrated methods including environmental deposition analysis, organic geochemistry analysis, petrophysical analysis, seismic interpretation, sweet spot delineation, and volumetric of gas in place (GIP) calculation. TAF observed both on the outcrop and well is transition deposit that consists of the dominance of shale and siltstone with interbedded of coal, sandstone, and limestone. Shale and siltstone of TAF have characteristic which is appropriate as a shale gas bearing, with sufficient organic content richness, suitable kerogen type, its maturity entering the early gas generation and proper brittleness index (BI). The sweet spot area is an area that has met the criteria for potential shale gas and determined by pay zone criteria. Depend on the criteria, Net to gross for shale gas is 0.158, early gas generation estimated at a depth of 10250 feet, and sweet spot area reaches 8.9 x 108 ft2. Thus, the total potential of shale gas resources from the calculation using the Ambrose method is 2.12 TCF.

Middle Miocene Black Shale of Airbenakat Formation in Berau Areas, Jambi: are they potential source rock?

The research location is geologically located in Jambi Sub-basin composed by Peneta Formation (KJp), Airbenakat (Tma), and Muara Enim (Tmpm). Specifically this research focuses on the physical characteristics and geochemistry of Middle Miocene black shale from Airbenakat Formation. The purpose of this research is to determine whether the black shale of this formation has the potential as a source rock. The method of this research are field observation that includes the description of rock samples and geological mapping, and laboratory analysis including rock geochemical analysis. Three samples were taken from black and fine-grained shale. Total organic carbon (TOC) values of the three samples taken ranged from 0.38-0.42%, the weight of TOC indicates a potentially close enough to produce hydrocarbons. the pyrolysis results show that the S1 data gives a value below 0.5 HC/g and S2 gives a value below 2.5 HC/g, so it can be seen that the three rock samples that tested are not sufficient enough to produce hydrocarbons. Overall the sample has a S2/S3 ratio ranging from 0.09-0.23 and Tmax-HI data has values ranging from 8-19 mg HC/g TOC, so it can be seen that the ratio S2/S3 less than 1 and the value of the index hydrogen below 50 mg HC/g TOC, It can be concluded that the samples are derived from type IV kerogen. The maximum temperature (Tmax) of pyrolysis shows a value of less than 4350C, where the values range from 350-4280C. So, it can be interpreted that the three samples are immature source rocks because the catagenesis phase to produce hydrocarbons has not been achieved. The conclusions is the three samples of black shale tested indicate potential as immature source rock and has the close enough ability to produce hydrocarbons. The result of the analysis then comparable with the result analysis of Airbenakat Formation Black Shale in Palembang Sub-basin which has fair-well ability to produce hydrocarbons.

Drilling Optimization of Tight Sands and Shale Gas Reservoir in Jambi Sub-Basin Based on Pore Pressure Estimation Using Drilling Efficiency Mechanical Specific Energy (DEMSE) and Bowers Methods

The subsurface pressure analysis is used to detect the overpressure and problems in the well that will be drilled based on exploration well data. Various problems were found while drilling operations carried out on A and B wells, namely, Kick and Pipe sticking which cause a high Non-Productive Time (NPT). This research is conducted to identify the mechanism of overpressure formation in Tight Sand Gas and Shale Gas in the Jambi Sub-Basin. Furthermore, to predict pore pressure using the Drilling Efficiency and Mechanical Specific Energy (DEMSE) and Bowers method. The final result will be a 3D pore pressure cube in the area based on quantitative analysis of post-stack seismic inversion. The results of the pore pressure analysis from the wells and the 3D pore pressure model indicate that top of overpressure occurs in the Gumai Formation, then it is decreasing gradually approaching the hydrostatic pressure on the Basement. The mechanisms of overpressure are caused by under compaction, fluid expansion (kerogen maturation). The Gumai Formation and Talang Akar Formation are shale rocks so the type of mud weight that is well used is oil based mud (OBM).

Strike-Slip Fault Deformation and Its Control in Hydrocarbon Trapping in Ketaling Area, Jambi Subbasin, Indonesia

Geologically, Ketaling area consists of a local high considered as flexure margin of Tempino-Kenali Asam Deep in west part and graben in east part also known as East Ketaling Deep. Numerous proven plays were established in Ketaling area with reservoir in early Miocene carbonate and middle Miocene sand. This area underwent several major deformations. Faults are developed widely, yet their geometrical features and mechanisms of formation remained so far indistinct, which limited exploration activities. With new three-dimensional seismic data acquired in 2014, this area evidently interpreted as having strike-slip mechanism. The objective of this study is to examine characteristic of strike slip fault and its affect to hydrocarbon trapping in Ketaling Area. Structural pattern and characteristic of strike slip fault deformation was examined with integration of normal seismic with variance seismic attribute analysis and the mapping of Syn-rift to Post-rift horizon. Seismic flattening on 2D seismic cross section with NW-SE direction is done to see the structural pattern related to horst (paleohigh) and graben. Typical flower structure, branching strike-slip fault system and normal fault in synrift sediment clearly showed in section. An echelon pattern identified from map view as the result of strike slip mechanism. Detail structural geology analysis show the normal fault development which has main border fault in the southern of Ketaling area dipping to the Southeast-East with NE-SW lineament. These faults related to rift system in Ketaling area. NW-SE folds with reactive NE-SW fault which act as hydrocarbon trapping in the shallow zone. This polyphase tectonic formed local graben, horst and inverted structure developed a good kitchen area (graben) and traps (horst, inverted structure). Subsequently, hydrocarbon accumulation potentials such as basement fractures, inverted syn-rift deposit and shallow zone are very interesting to explore in this area.

Characterization of Basement Fracture Reservoir In Field ‘X’, South Sumatera Basin, Based On The Analysis of Core And FMI Log

Basement reservoir is a reservoir that is located in the basement rock, comprised of either igneous rock or metamorphic rock that has secondary porosity, resulting in its capability to store oil and gas. The research was conducted at field 'X' that is located at South Sumatra basin and it is a part of Jambi Sub-Basin. The study was focused on discussing hydrocarbon potential in Fields 'X', particularly at the basement metamorphic rock. The study was conducted at two wells in the field. The secondary porosity system of the basement is fracture porosity. Fracture analysis as secondary porosity system was performed on two wells, HA-1 and HA-2, by using FMI log interpretation. Based on the analysis of fracture on HA-1 well, the trend of fracture system is Northeast - Southwest (NE-SW) with a fracture porosity of 1.49%. On a different note, the trend of fracture system on HA-2 wells is East Northeast - West Southwest (ENE-WSW) with a fracture porosity of 0.888%. The effect of rock properties itself has little influence on the number of fractures as opposed to the effect of surrounding tectonic forces. The fractures are controlled by geological structures following Jambi pattern that has an orientation of Northeast - Southwest (NE-SW). Although the fracture porosity is relatively small, it is enough to storing hydrocarbons in economical quantity.

PALYNOLOGICAL STUDY OF THE JAMBI SUB-BASIN, SOUTH SUMATRA

The palynological study of the Jambi Sub-basin, South Sumatera is carried out to construct biostratigraphy of the identifi ed formation. The palynological analysis provides an age interpretation as well as environment of depositional interpretation. The study uses outcrop samples which were collected from Merangin River, Muara Jernih and Mengupeh areas. The age of the studied sediment ranges from Early to Middle Miocene. The top Middle Miocene age is identifi ed by the occurrence of pollen Florschuetzia levipoli and Florschuetzia meridionalis, whilst the base of Early Miocene is marked by the appearance of nannoplankton Sphenolithus compactust. The studied sediment cropping out at the Merangin River and Muara Jernih area interpreted as Talang Akar Formation was deposited in a lower delta plain to delta front during Early Miocene. In the Mengupeh area, this sediment shifted landward into upper delta plain to lower delta plain environment during Middle Miocene.

Perbandingan karakteristik lingkungan pengendapan, batuan sumber, dan diagenesis Formasi Lakat di lereng timur laut dengan Formasi Talangakar di tenggara Pegunungan Tigapuluh, Jambi

http://dx.doi.org/10.17014/ijog.vol1no4.20061The Central Sumatera Basin and the Jambi Subbasin is separated by the Tigapuluh High. During Late Oligocene – Middle Miocene, the Lakat Formation was deposited in fl uvial, fl ood plain associated with swamp, and tidal environments, whereas the Jambi Subbasin was occupied by the deposition of the Talangakar Formation in fl uvial and deltaic environments. The provenance of both formations was derived from the Tigapuluh and Barisan Mountain Highs. Diagenesis stage of the Talangakar Formation is higher (Mesogenetic mature B) than that of the Lakat Formation (Mesogenetic immature). This is because the Talangakar Formation was deposited within an unstable basin formed by horst, and graben structures which were still active during the deposition of the formation. On the other hand, the Lakat Formation was deposited in a more stable basin.

Basin Modeling of Jambi Subbasin, South Sumatra, Indonesia: ABSTRACT

Basin Modeling of Jambi Subbasin, South Sumatra, Indonesia: ABSTRACT