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Lower Karoo Sedimentation in Moatize Basin, Mozambique: Analogue for Understanding the Deep Rift Sequence in Offshore Rovuma Basin
Pendkar, Narender (PETRONAS Carigali Sdn. Bhd.) | Rubino, Jean-Loup (Total) | Jean-Baptiste Baby, Guillaume (U. of Rennes) | Sia, Simon Seak Lung (PETRONAS Carigali Sdn. Bhd.) | Prasetyotomo, Wahyu Singgih (PETRONAS Carigali Sdn. Bhd.)
Abstract This paper reports observations carried out on Carboniferous to Permian sedimentary rocks in Moatize Basin in Tete Province. The outcrops of Vuzi, Moatize and Matinde Formations ranging in age from Late Carboniferous to Late Permian were logged and sampled along river sections. The Vuzi Formation is made up of diamictites with thin bedded sandstone intercalations, laminated shale and localized hemispheroidal stromatolitic limestone which were deposited in glacio-fluvial to lacustrine depositional systems. The stromatolitic and laminated limestone was formed during a deglaciation episode on the lacustrine margin. The younger outcrops of Moatize Formation are characterized by thick stacked braided and meandering fluvial, and lacustrine deposits with intervening coal seams. The lacustrine deposits are characterized by fissile shales with thin, laterally persistent fine grained sandstones and siltstones. The lacustrine depositional systems range from shallow, with localized deposits of several meters of laminated grey silty shales within the confines of fluvial deposits, to deep, with a thickness of tens of meters having dark grey shale associated with rhythmic turbidites. Introduction The spate of hydrocarbon discoveries in Rovuma Basin, Mozambique during the recent years (Fruhauf, 2014) have paved way for an outline of petroleum systems. While the role of Tertiary and Mesozoic geological elements are well understood (Salman and Abdula, 1995), the stratigraphic and tectonic framework of deeper Karoo sedimentary sequences has not been completely deciphered (Figure 1). The regional sequence stratigraphic analysis studies carried out by Sapri et al. (2013) in southern part of Rovuma basin has established up to five sequences from Triassic to the Present. With absence of well data, the characteristics of the deeper Karoo sedimentaries could not be recognized with confidence based on seismic data alone. The objectives of the study are to use outcrops as analogues for understanding sedimentological and source rock characteristics for the deeper part of rifted sedimentary sequence within the offshore Rovuma Basin. Moatize Basin The Karoo sedimentation in various south and central African basins has been extensively documented (Cairncross, 2001; Catuneanu et al., 2005). For this study, Moatize Basin was chosen as it offers excellent outcrops of sedimentary rocks deposited in a rift sequence ranging in age from Late Carboniferous to Late Permian, making it an ideal analogue for understanding sedimentological and source rock characteristics for the deeper part of rifted sedimentary sequence within the offshore basins like Rovuma, the site for recent prolific hydrocarbon discoveries on the eastern margin of Africa. In addition to the coal bearing outcrops of the Permian encountered along the Muaradzi and Moatize river sections, the Vuzi Formation, the equivalent of the Dwyka Tillite was also examined along the Murongozi river section (GTKa, 2006). The geology of the Tete Province is structurally dictated by the regional Zambezi Rift, which trends E-W from the Zambia-Zimbabwe border, then swings SE to S-SE through Tete. The rift was formed in Proterozoic basement rocks, developing into a zone of active extensional tectonism and sedimentary deposition. The Proterozoic basement comprises of igneous, crystalline rocks, schists and metasediments (GTKa 2006). The geological structure in the Moatize Basin is dominated by a series of high angle faults, which divide the basin (Vasconcelos, 2000).
- Phanerozoic > Paleozoic > Carboniferous > Pennsylvanian (0.69)
- Phanerozoic > Paleozoic > Permian > Lopingian (0.54)
- Geology > Sedimentary Geology > Depositional Environment > Continental Environment > Lacustrine Environment (1.00)
- Geology > Rock Type > Sedimentary Rock > Clastic Rock > Mudrock > Shale (1.00)
- North America > Canada > New Brunswick > Moncton Basin > Albert Formation (0.99)
- Africa > South Africa > Karoo Basin (0.99)
- North America > United States > Texas > Permian Basin > Yeso Formation (0.94)
- (25 more...)
Sedimentology and Diagenesis of Deeper Clastic Reservoirs: Some Insights from Recent Exploration Wells in Offshore Sarawak, Malaysia
Pendkar, Narender (PETRONAS Carigali Sdn. Bhd.) | Bt. Zainun, Fakhitah (PETRONAS Carigali Sdn. Bhd.) | Parsuram, Satyabrata Nayak (PETRONAS Carigali Sdn. Bhd.) | Bin A. Aziz, Anuar (PETRONAS Carigali Sdn. Bhd.) | Bin Ali, Mohd Firdaus (PETRONAS Carigali Sdn. Bhd.) | Bt. Embi, Rahida (PETRONAS Carigali Sdn. Bhd.)
Abstract The present study integrates the laboratory data from sidewall cores (RCA, petrography, XRD and SEM) with sedimentological observations (cores, wireline and image logs). Compositionally the sandstones are fine to medium grained sublitharenites to litharenites, with lithic fragments of metamorphic, reworked sedimentary and volcanic rock types. The diagenetic events observed in the sandstones are compaction, dissolution of feldspar and lithics, cementation (pyrite, silica, calcite, siderite dolomite and ferroan carbonate), and clay formation (kaolinite and illite). The porosity type comprises of primary intergranular, secondary and microporosity. The environment show a gradual change from upper reaches of the lower coastal plain with fluvial dominant regime for Cycle I to lower reaches of the lower coastal plain with increasing marine influence in Cycle II. The reservoir quality is controlled by both petrofacies and grain size variations. Introduction The ongoing drilling campaign in offshore Sarawak has resulted in the discovery of potential reservoirs from deeper Cycle I and II, previously considered tight and thus opening new frontiers for exploration. The study area lies within several geological provinces of Central Luconia, SW Luconia and West Balingian (Figure 1 and 2). The generalized stratigraphy, tectonics and paleogeographic evolution for the Cycle I and II are depicted in Figure 1 (Madon, 1999). In the subsurface the Cycle I and II sediments can be recognized using biostratigraphy, well logs and to a limited extent on seismic datasets; the concept of Cycle as originally defined by Ho Kiam Fui (1978) has been used for defining the cycle boundaries. Accordingly, the base of a cycle is taken for practical reasons at the base of the most transgressive interval. The electrolog signatures across the block show good lateral correlations and can be used with reasonable confidence (Figure 2). Methodology The present study was undertaken to comprehensively evaluate the sedimentological controls for understanding the reservoir quality from eight exploratory wells obtained during the last few decades. The observations and datasets from limited conventional and sidewall cores form the basis of this study. Laboratory data (RCA, petrography, XRD and SEM), wireline and image logs were integrated to understand the petrofacies, diagenesis and depositional trends. The petrographic, mineralogical and textural data is limited especially for the deeper Cycle I sandstones. The analytical datasets have been standardized and plotted to make meaningful interpretations and comparisons. For understanding the sandstone compositions, the modal data obtained from petrographic examination was plotted using Folk (1980) techniques for classification of sandstones and lithic grains.
- North America > United States > Texas (0.47)
- Asia > Malaysia > Sarawak > South China Sea (0.24)
- Geology > Sedimentary Geology (1.00)
- Geology > Rock Type > Sedimentary Rock > Clastic Rock > Sandstone (1.00)
- Geology > Mineral (1.00)
- Geology > Geological Subdiscipline (1.00)
- North America > United States > Texas > Frio Formation (0.99)
- Europe > Germany > Subhercynian Basin (0.99)
- Asia > China > South China Sea > Vung May Basin (0.95)
- Reservoir Description and Dynamics > Reservoir Characterization > Sedimentology (1.00)
- Reservoir Description and Dynamics > Reservoir Characterization > Geologic modeling (1.00)
- Reservoir Description and Dynamics > Reservoir Characterization > Exploration, development, structural geology (1.00)
- Reservoir Description and Dynamics > Formation Evaluation & Management > Open hole/cased hole log analysis (1.00)
An Integrated Approach of Sequence Stratigraphic Study in Southwestern of Malay Basin
Wei Chen, Harry Wong (PETRONAS Carigali Sdn. Bhd.) | Ab. Aziz, Sham Shukriah (PETRONAS Carigali Sdn. Bhd.) | B Mahmud, Othman Ali (PETRONAS Carigali Sdn. Bhd.) | Pendkar, Narender (PETRONAS Carigali Sdn. Bhd.) | Bt Sapri, Dayang Haspariah (PETRONAS Carigali Sdn. Bhd.)
Abstract This paper presents the results of an integrated sequence stratigraphy approach using seismic, well log and biostratigraphic data to build sequence stratigraphic framework and its implication in petroleum system understanding for the southwestern part of the Malay Basin. Seismic data were used to interpret third order Sequence Boundaries (SB) and Maximum Flooding Surfaces (MFS) based on reflector terminations. Well log analyses were carried out to support the interpretations and were cascaded down to define the third order sequences and associated system tracts (LST, TST and HST). Biostratigraphic data were also used to validate the SB, MFS and the paleo-environments. This study has subdivided the sedimentary successions into six 3 order sequences namely Sequence 1 to Sequence 6. Each of the sequence is bounded by sequence boundary, which has been calibrated with the Malay Basin Chronostratigraphic Chart (PETRONAS, 2007). Two source rocks are present for the study area- the deeper synrift section with source rocks deposited in a lacustrine environment (Late Oligocene age) and the shallower source rock deposited in a marine inner neritic environment (Early Miocene age). The migration pathway for the deeper section is through faults, and from lateral migration for the shallow section. The study also indicates that the potential reservoirs are thinning basinward (southwest to northeast). The potential reservoirs are interpreted to be the fluvial, lacustrine and shallow marine sands. Data from several key drilled wells suggests that reservoir is at low risk in the sand-prone areas of the southeastern part compared to the northern part which is more shale-prone. Based on the present study, it is inferred that trap integrity is the main risk for petroleum system. While a good top seal is provided by the main regional shales in deeper section, the seal at the shallow sections are from thin and discontinuous intra-formational shales that are present in every sequence. The presence of younger faults cutting through the reservoir may cause the potential for hydrocarbon leakage. The present study has identified five potential plays and also established the regional sequence stratigraphic framework in southwestern of Malay Basin.
- Phanerozoic > Cenozoic > Neogene > Miocene (0.89)
- Phanerozoic > Cenozoic > Paleogene > Oligocene (0.72)
- Geology > Sedimentary Geology > Depositional Environment > Continental Environment > Lacustrine Environment (1.00)
- Geology > Geological Subdiscipline > Stratigraphy > Sequence Stratigraphy (1.00)
- Geology > Geological Subdiscipline > Economic Geology > Petroleum Geology (1.00)
- Geology > Rock Type > Sedimentary Rock > Clastic Rock > Mudrock > Shale (0.80)
- Asia > Vietnam > Gulf of Thailand > Pattani Basin (0.99)
- Asia > Thailand > Gulf of Thailand > Pattani Basin (0.99)
- Asia > Myanmar > Gulf of Thailand > Pattani Basin (0.99)
- (4 more...)