Eko Budi Lelono
Research and Development Centre for Oil and Gas Technology "LEMIGAS"

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TROPICAL EOCENE PALYNOMORPHS FROM THE TORAJA FORMATION, KALUMPANG, SOUTH SULAWESI Eko Budi Lelono
Scientific Contributions Oil and Gas Vol 26 No 1 (2003)
Publisher : Testing Center for Oil and Gas LEMIGAS

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.29017/SCOG.26.1.991

Abstract

This study enables to prove the occurrence of the tropical Eocene palynomorphs within the South Sulawesi area.
PLEISTOCENE PALYNOLOGY OF THE WAIPONA BASIN, PAPUA Eko Budi Lelono
Scientific Contributions Oil and Gas Vol 31 No 2 (2008)
Publisher : Testing Center for Oil and Gas LEMIGAS

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.29017/SCOG.31.2.1001

Abstract

The Pleistocene sediment from a single well drilled on the back bone of Papua provides good pollen recovery which shows the mixture of the Australian and Asian elements. The well drilled the sediment more than 3000 meter deep which is mostly assigned to Pleistocene age. Only small part of the basal section belongs to Pliocene age. In order to obtain accurate interpretation, the age interpretation is also defined using other disciplines including foraminifera and nannoplankton. The Australian affinity appears as an origin since this island has derived from the Australian continent. On the other hand, the existence of Asian palynomorphs within the studied sediment indicates the dispersal of Asian flora into East Indonesia following the arrival of the Australian plates at about the end of Oligocene. The Asian taxa then migrated to the land mass of New Guinea which rose above sea level from about Middle Miocene onward. In the studied section, shallow marine sediment in the upper interval contains sufficient palynological assemblages which clearly indicate climatic changes from dry or seasonal to wet climate as reflected on the changes of the proportion of dry/ seasonal and wet climate indicators. Unfortunately, due to low pollen recovery, the climate condition of the lower interval can be hardly interpreted. This could have happened because the sediment of the lower interval was deposited in deep marine environment, which was situated far away from the pollen sources in the continent.
THE CONTRIBUTION OF PALYNOLOGY IN FIELD DEVELOPMENT Eko Budi Lelono
Scientific Contributions Oil and Gas Vol 29 No 1 (2006)
Publisher : Testing Center for Oil and Gas LEMIGAS

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.29017/SCOG.29.1.1020

Abstract

The reliable interpretation of lateral reservoir distribution is required to gain high accuracy of reserve estimation in the oil field. Apparently, the geometry of reservoirs influences the volume of hydrocarbon. Widespread reservoirs are more preferred than isolated reservoirs because the former tend to store much larger volume of hydrocarbon than the later which usually produce limited volume of hydrocarbon. The lateral reservoir connectivity can be approached using various methods such as well log correlation, seismic correlation, biostratigraphic correlation, etc. In fact, each method sometime provides distinct result compared to that using another method. Therefore, the integration of those methods is actually needed to obtain reliable result. In the studied field, reservoir correlation was firstly constructed base on well log and seismic correlations. It was concluded that each reservoir could be traced along the studied wells. However, in order to cross check this conclusion it is applied palynological correlation as the studied sections are well recognized to represent deltaic sediment which yields rich palynomorph assemblage. It is now believed that palynology will be able to refine the correlation which was reconstructed base on well log and seismic. Data obtained during the analysis is considered to be confidential as this is provided for commercial work which is not public domain. Therefore, detail information of the studied wells cannot be revealed within this paper. The wells are named using numbers such as 1, 2 and 3, whilst reservoirs are labelled in alphabetical order, for example A, B and C. The studied wells were drilled in the oil field, so called Field "X" (Figure 1). Due to space limitation, only palynological data relevant to the correlation and sequence stratigraphic analysis of the studied wells (1, 2 and 3) are presented within this paper (Figures 3, 4 and 5). These data include the distribution of selected taxa, especially those which derived from marine, mangrove, back-mangrove, riparian, peatswamp and freshwater vegetations. Lithology is inferred from wireline logs which were provided by the client. These logs are shown together with pollen diagrams as seen in Figures 3, 4 and 5.
EOCENE-OLIGOCENE CLIMATE BASED ON PALYNOLOGICAL RECORDS Eko Budi Lelono
Scientific Contributions Oil and Gas Vol 29 No 2 (2006)
Publisher : Testing Center for Oil and Gas LEMIGAS

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.29017/SCOG.29.2.1023

Abstract

This study is a part of the investigation on Tertiary paleoclimate conducted by LEMIGAS Stratigraphy Group. The paleoclimate reconstruction covers most area of western Indonesia including South Sumatra Basin, Sunda-Asri Basin, Northeast Java Basin South Kalimantan and Northeast Java Basin, West Natuna and South Sulawesi (Figure 1). This paper is aimed to figure out the regional paleoclimate of western Indonesia which occurred during Eocene-Oligocene. In fact, the knowledge of paleoclimate is useful to define sea level changes which are believed to have relationship with stratigraphy and sedimentology of these areas. The paleoclimate interpretation can be approached using different tools such as biostratigraphy and geochemistry. In this study, paleoclimate is interpretated based on biostratigraphy (microfossil evidences) including palynomorph and foraminifer. Palynomorphs were mainly applied on the non-marine to transitional sections, whilst foraminifers were used in interpreting shallow to deep marine sediments. In fact, most interpretations rely on palynological evidences as these simply provide suitable data for paleoclimate analysis. In case of both microfossils appear in the same section, the paleoclimate interpretation based on palynomorph can be placed in a certain stratigraphic level which is defined based on the occurrence of the age-restricted foraminifer. The paleoclimate interpretation of certain strati- graphic level is based on the compilation of palynological and foraminiferal data deriving from different areas. This method is used to obtain representative picture of paleoclimate which occurs in the selected stratigraphic range of the western Indonesia
PLEISTOCENE PALYNOLOGY OF EAST JAVA Eko Budi Lelono
Scientific Contributions Oil and Gas Vol 29 No 3 (2006)
Publisher : Testing Center for Oil and Gas LEMIGAS

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.29017/SCOG.29.3.1027

Abstract

This study is a part of geological investigation on Pleistocene sediment in East Java in order to evaluate hydrocarbon potential within this sediment of this area. The area of study is located in the on-shore East Java (Figure 1). It is financially supported by the oil company as this is commercial work done by LEMIGAS Exploration Department. Therefore, data used in this paper will be incompletely presented as they are confidential. The name of the studied wells and their precise locations are hided in this paper. Data used in this study derives from three wells namely R, S and T. Three different disciplines are applied in this study including palynology, micropaleontology and nannoplankton analyses which are useful for crosschecking purposes. Apparently, the integration of these analyses gains accurate interpretation of stratigraphy and depositional environment. The area of study is in East Java Basin which can be classified as a classical back-arc basin. During Pleistocene, the area of study was marked by regional uplift and the cessation of open marine sedimentation (LEMIGAS, 2005). Therefore Pleistocene age was dominated by non-marine deposition. Generally, this type of sediment is separated from the underlying layer by an unconformity (LEMIGAS, 2005). Most Pleistocene sediment consists of volcanoclastic as a result of volcanic activity which related to uplifting period. It is possible that volcanic activity was responsible for the burning of grass as indicated by the occurrence of charred Gramineae cuticles. The previous investigations on Pleistocene sediment showed the domination of grass pollen of Monoporites annulatus which suggested the expansion of dry climate during Pleistocene glacial maxima. The pollen diagram from Lombok Ridge produced by van der Kaas (1991a) proves the domination of Gramineae pollen during Pleistocene (Figure 2). The period of dry climate (glacial climate) is characterised by abundant Gramineae pollen, whilst the period of wetter climate (interglacial climate) is indicated by an increase of coastal and mangrove palynomorphs, but greatly reduced frequencies of Graminaae pollen (Morley, 2000). In addition, Rahardjo et al. (1994) referred to the high abundance of Monoporites annulatus to propose Pleistocene pollen zone of M. annulatus (Figure 3).
PALYNOLOGICAL EVENTS OF THE TALANG AKAR FORMATION IN THE ON-SHORE AREA OF THE SOUTH SUMATRA BASIN Eko Budi Lelono
Scientific Contributions Oil and Gas Vol 27 No 2 (2004)
Publisher : Testing Center for Oil and Gas LEMIGAS

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.29017/SCOG.27.2.1049

Abstract

South Sumatra has been well known as the one of the largest hydrocarbon producers in Indonesia. Due to its potentiality, South Sumatra has been explored since the Dutch era. Million barrels of oil have been pumped out from this area and many unpublished reports and papers have been made regarding the remaining reserve of this area. This study focuses on Talang Akar Formation which is considered as the main reservoir in South Sumatra. Talang Akar Formation is interpreted to be formed in a deltaic environment (De Coster, 1974). The deltaic sediment must have contained excellent palynomorph assemblage as demonstrated by the previous authors (Hasjim, 1993, Morley, 1995 and LEMIGAS 2001a, b and c). On the other hand, marine microfossils show poor recovery including foraminifers and nannoplankton. This condition is understandable as marine microfossils are difficult to develop in the transition environment. For this reason, palynology is intensively studied as a powerful tool to comprehend the stratigraphy of the Talang Akar Formation.The deposition of Talang Akar Formation was influenced by the tectonic event during Late Cretaceous to Early Tertiary which caused the occurrence of Semangko Dextral Fault (Suwidiyanto, 2003). This fault resulted in the formation of horst and graben which allowed sedimentation of Lahat Formation and the Lower Talang Akar Formation in the low topography. Subsequently, sea level increased rapidly drowning up the deposition center which resulted in the sedimentation of the Upper Talang Akar Formation and limestone Baturaja Formation (Suwidiyanto, 2003). Based on lithological character, Talang Akar Formation is separated into Great Sand Member (GRM) occupying lower part of this formation and Transition Member (TRM) situating in the upper formation. GRM was formed in the fluvial to delta plain environment, whilst TRM was deposited in delta plain to pro-delta environment (De Coster, 1974). The environmental change from fluvial-delta plain of GRM (non-marine) to delta plain-prodelta of TRM (nonmarine to transition) suggests the occurrence of transgressive phase. Palynologically, this change must be reflected in the palynological assemblage. In fact, TRM yields more brackish palynomorphs than those of GRM. In contrary, GRM especially those of river channel deposits are characterised by regular occurrence of riparian (freshwater) pollen such as Marginipollis concinus and Pandaniidites sp. (LEMIGAS, 2001a, b and c).Although palynological investigations were frequently conducted within the Talang Akar Formation, the results of these investigations were restricted on age interpretation and paleoenvironment analysis. There are more information can be obtained from the palynological data. Therefore, it is required extra efforts to elaborate data becoming useful information such as palynological event, sea level changes and paleoclimate. This study intends to explore the stratigraphy of the Talang Akar Formation based on its palynological and other micro-fossil content which focuses on palynological characteristic of the Talang Akar Formation, palynological event and other biostratigraphic information (zones, age and depositional environment).
THE PALEOGENE SEDIMENT IN SOUTH SUMATRA - WHERE HAS IT GONE? Eko Budi Lelono
Scientific Contributions Oil and Gas Vol 27 No 3 (2004)
Publisher : Testing Center for Oil and Gas LEMIGAS

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.29017/SCOG.27.3.1056

Abstract

It has been widely known that South Sumatra Basin yields Paleogene successions (Ferdiyanto et al., 2003). These successions consist of Lemat and Talang Akar Formations (De Coster, 1974) or Lahat and Lower Talang Akar Formations (Clure et al., 2002). The regional stratigraphy of the South Sumatra Basin is shown in Figure 1. The Paleogene sediment is interpreted to form within the occurrence of horst and graben which was caused by the formation of Semangko dextral fault as a result of Late Cretaceous-Early Tertiary tectonism (Suwidiyanto, 2003). In its study, LEMIGAS (2001) classified these successions as the synrift deposit because they were deposited during rifting phase which presumably occurred in Oligo-Miocene age. In fact, finding the Paleogene synrift sediment in South Sumatra is a serious matter. Most studied wells provided by the client lacks biostratigraphic evidences of Paleogene age. The author contributed to this study by investigating the fossil contents of the studied sediment. The result of the biostratigraphic analysis of this sediment encourages the author to publish it as presented in this paper. Therefore, this paper is intended to disclose a comprehensive biostratigraphic data which is obtained from three different disciplines including foraminifer, nannoplankton and palynology. The Early Tertiary sediment in South Sumatra was generally deposited in the non-marine to transition (deltaic) environment (De Coster, 1973). The previous investigators show that this type of sediment contains rich palynomorph (Hasjim, 1993, Morley, 1995 and Lelono, 2003). Apparently, the age determination mostly referred to the occurrence of age diagnostic pollen. In this case, the appearance of peat swamp element of Meyeripollis naharkotensis is used to indicate the Oligocene sedi- ment (LEMIGAS, 1998). Unfortunately, it was lack of support from other microfossil study such as foraminifer and nannoplankton which resulted in least confidence to this interpretation. The occurrence of M. naharkotensis has been widely used to designate the Late Paleogene over the Southeast Asian Region (Morley, 1991 and Rahardjo et al., 1994). However, the stratigraphic range of M. naharkotensis is somewhat ambiguous as this pollen associates with the occurrence of coals indicating the ever-wet warm climate (Morley, 1991). In fact, this pollen ranges up as far as basal Late Miocene as recorded in the coaly succession of East Kalimantan (Lelono, 2003). On the other hand, in East Java, well section with least coal development shows the distribution of M. naharkotensis along the Oligocene section (Lelono, 2003). Nichols (1999) stated that the age indicators strongly controlled by facies reduce their stratigraphic value. This means that the occurrence of M. naharkotensis does not necessarily indicate the Late Paleogene. Therefore, it is suggested to consider the existence of coal lithology in applying M. naharkotensis for age interpretation. The occurrence of (?Late Oligocene)-Early Miocene rift sediments led to the conclusion that the rifting phase triggered by Late Cretaceous-Early Tertiary tectonism occurred slightly later in South Sumatra than that in Central Sumatra (LEMIGAS, 2001). Meanwhile, In Central Sumatra, rift deposit occurred during Eocene-Oligocene time (Williams et al., 1985 and Longley et al., 1990). Although De Coster (1974) assumed that South and Central Sumatra Basins had very similar and related history and could be considered as one large basin with many troughs and grabens, the recent biostratigraphic data suggest distinct period of basin development between South and Central Sumatra. This interpretation may not be obtained without accurate biostratigraphic data. Therefore, this paper is published to provide biostratigraphic information which allows explorationists to possess better understanding of the South Sumatra Basin.
LEMIGAS BIOSTRATIGRAPHIC DATA BANK CONSTRUCTION Eko Budi Lelono
Scientific Contributions Oil and Gas Vol 25 No 1 (2002)
Publisher : Testing Center for Oil and Gas LEMIGAS

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.29017/SCOG.25.1.1062

Abstract

In accordance with the tasks and functions of LEMIGAS, the Stratigraphy Group of Exploration Division has been constructing a data bank of biostratigraphy which covers the whole areas of Indonesia. This project is financially supported by LEMIGAS and it has been started since 1997. The objective of this project is to collect biostratigraphic data across the Indonesian region. The data are differentiated into two types. The first type is raw data which were extracted from rock samples after laboratory preparation. The second type is data provided from the existing biostratigraphic charts. In addition, data generally derived from wells. Data obtained from the charts need to be re-analysed in order to gain accurate stratigraphic interpretation. The data bank is built by using a computer software called StrataBugs. This software was selected because it provides facilities to perform many types of biostratigraphic diagram which support different analyses. It is also compatible with other biostratigraphic software. The first five years were concentrated on western Indonesia. There are 285 data collected from various areas which consist of foraminifera, nannoplankton and palynology. Apparently, the number of data tends to increase each year.The data bank can be used for either scientific aims or managerial purposes. For scientific aims, these data are temporarily used for reconstructing biozones and palaeoenvironment. However, many analyses can be established by referring to these data such as palaeoclimate, sea level changes and palaeogeography. In fact, two papers have been published based on these data. For managerial purposes, these data may be used to evaluate the performance of Stratigraphy Group relating to commercial works because most data were supplied from service work. These data also support the management to prepare an appropriate strategy to achieve reasonable performance. 
OBTAINING THE SUITABLE TECHNIQUES FOR PALYNOLOGICAL PREPARATION Eko Budi Lelono
Scientific Contributions Oil and Gas Vol 24 No 2 (2001)
Publisher : Testing Center for Oil and Gas LEMIGAS

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.29017/SCOG.24.2.1074

Abstract

The term of “standard techniques” in preparation is no longer accepted since every sample has discrete characteristic which may require different treatment. Experiments prove that the modifications are needed to process the Eocene samples from Central Java and South Sulawesi.