Determination of Reservoir Flow Units from Core Data: A Case Study of the Lower Cretaceous Sandstone Reservoirs, Western Bredasdorp Basin Offshore in South Africa

Opuwari, Mimonitu; Mohammed, Saeed; Ile, Charlene

doi:10.1007/s11053-020-09722-3

Cited by 17 publications

(13 citation statements)

References 52 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…(2) Vsh = 0.33 2 (2 * IGR) − 1 At the same time, the total porosity was estimated from the density log using an average matrix density value of 2.67 g/cm 3 from core grain density (Asquith and Gibson 1982;Opuwari 2010) from Eq. 3:…”

Section: Petrophysical Analysismentioning

confidence: 99%

Static reservoir modeling using stochastic method: a case study of the cretaceous sequence of Gamtoos Basin, Offshore, South Africa

Ayodele

Chatterjee

Opuwari

2021

J Petrol Explor Prod Technol

View full text Add to dashboard Cite

Gamtoos Basin is an echelon sub-basin under the Outeniqua offshore Basin of South Africa. It is a complex rift-type basin with both onshore and offshore components and consists of relatively simple half-grabens bounded by a major fault to the northeast. This study is mainly focused on the evaluation of the reservoir heterogeneity of the Valanginian depositional sequence. The prime objective of this work is to generate a 3D static reservoir model for a better understanding of the spatial distribution of discrete and continuous reservoir properties (porosity, permeability, and water saturation). The methodology adopted in this work includes the integration of 2D seismic and well-log data. These data were used to construct 3D models of lithofacies, porosity, permeability, and water saturation through petrophysical analysis, upscaling, Sequential Indicator Simulation, and Sequential Gaussian Simulation algorithms, respectively. Results indicated that static reservoir modeling adequately captured reservoir geometry and spatial properties distribution. In this study, the static geocellular model delineates lithology into three facies: sandstone, silt, and shale. Petrophysical models were integrated with facies within the reservoir to identify the best location that has the potential to produce hydrocarbon. The statistical analysis model revealed sandstone is the best facies and that the porosity, permeability, and water saturation ranges between 8 and 22%, 0.1 mD (< 1.0 mD) to 1.0 mD, and 30–55%. Geocellular model results showed that the northwestern part of the Gamtoos Basin has the best petrophysical properties, followed by the central part of the Basin. Findings from this study have provided the information needed for further gas exploration, appraisal, and development programs in the Gamtoos Basin.

show abstract

Section: Petrophysical Analysismentioning

confidence: 99%

Static reservoir modeling using stochastic method: a case study of the cretaceous sequence of Gamtoos Basin, Offshore, South Africa

Ayodele

Chatterjee

Opuwari

2021

J Petrol Explor Prod Technol

View full text Add to dashboard Cite

show abstract

“…Then, we create hydraulic ow units using the FZI boundaries. This method has been successfully applied and documented by researchers in carbonate and clastic reservoirs 9,24,49 .…”

Section: Hydraulic Flow Unitmentioning

confidence: 99%

“…The LFZ of well OW1 is bounded vertically at the top and bottom by HFZ. The LZF is interpreted to provide a lithofacies A and lithofacies B contact that allows uid ow between the high ow zones 24,68 , implying that the HFZs are in communication. The…”

Section: Lfzmentioning

confidence: 99%

“…Despite the previous studies conducted on ow zonation in the Bredasdorp Basin [24][25][26] for the western, central, and northwestern parts of the Bredasdorp Basin, all the studies are targeted at the gas eld in the Bredasdorp Basin. Based on our knowledge, there is no published work regarding reservoir rock typing or ow zonation of an oil eld in the Bredasdorp Basin.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Petrophysical Core-Based Zonation of An Oil Field In The Bredasdorp Basin South Africa

Opuwari¹,

Afolanyan²,

Mohammed³

et al. 2021

Preprint

Self Cite

View full text Add to dashboard Cite

This study aims to generate rock units based on core permeability and porosity of an oil field in the Bredasdorp Basin offshore South Africa. In this study, we identified and classified lithofacies based on sedimentology reports in conjunction with well logs. Lucia's petrophysical classification method is used to classify rocks into three classes. Results revealed three lithofacies as A(sandstone, coarse to medium-grained), B (fine to medium-grained sandstone), and C (carbonaceous claystone, finely laminated with siltstone). Lithofacies A is the best reservoir quality and corresponds to class 1, while lithofacies B and C correspond to class 2 and 3, which are good and poor reservoir quality rock, respectively. An integrated reservoir zonation for the rocks is based on four different zonation methods (Flow Zone indicator (FZI), Winland r35, Hydraulic conductivity (HC), and Stratigraphy modified Lorenz plot (SMLP)). Four flow zones were identified as high(HFZ), moderate (MFZ), Low (LFZ), and tight (TFZ), respectively. The HFZ is the best reservoir quality composed of a megaporous rock unit, with an average FZI value between 5 to 10µm, and HC from 40 to 120 mD/v3, ranked as very good. The most prolific flow units (HFZ and MFZ zones) form more than 75 % of each well's flow capacities. The TFZ is the most reduced rock quality composed of impervious and nanoporous rock. There appears to be a slight increase of illite in the tight and low zones that block pore throats, thereby decreasing permeability. Therefore, illite has a dominant effect on flow zones. Quartz is the dominant framework grain, and siderite is the dominant cement that affects flow zones. This study has demonstrated a robust approach to delineate flow units in an oilfield. A novel sandstone reservoir zonation classification criteria developed from this study can be applied to other datasets of sandstone reservoirs with confidence.

show abstract

“…Despite the previous studies conducted on flow zonation in the Bredasdorp Basin 24 – 26 for the western, central, and northwestern parts of the Bredasdorp Basin, all the studies are targeted at the gas field in the Bredasdorp Basin. Based on our knowledge, there is no published work regarding reservoir rock typing or flow zonation of an oil field in the Bredasdorp Basin.…”

Section: Introductionmentioning

confidence: 99%

Petrophysical core-based zonation of OW oilfield in the Bredasdorp Basin South Africa

Opuwari

Afolayan

Mohammed

et al. 2022

Sci Rep

Self Cite

View full text Add to dashboard Cite

This study aims to generate rock units based on core permeability and porosity of OW oilfield in the Bredasdorp Basin offshore South Africa. In this study, we identified and classified lithofacies based on sedimentology reports in conjunction with well logs. Lucia's petrophysical classification method is used to classify rocks into three classes. Results revealed three lithofacies as A (sandstone, coarse to medium-grained), B (fine to medium-grained sandstone), and C (carbonaceous claystone, finely laminated with siltstone). Lithofacies A is the best reservoir quality and corresponds to class 1, while lithofacies B and C correspond to class 2 and 3, which are good and poor reservoir quality rock, respectively. An integrated reservoir zonation for the rocks is based on four different zonation methods (Flow Zone indicator (FZI), Winland r35, Hydraulic conductivity (HC), and Stratigraphy modified Lorenz plot (SMLP)). Four flow zones Reservoir rock types (RRTs) were identified as RRT1, RRT3, RRT4, and RRT5, respectively. The RRT5 is the best reservoir quality composed of a megaporous rock unit, with an average FZI value between 5 and 10 µm, and HC from 40 to 120 mD/v3, ranked as very good. The most prolific flow units (RRT5 and RRT4 zones) form more than 75% of each well's flow capacities are supplied by two flow units (FU1 and FU3). The RRT1 is the most reduced rock quality composed of impervious and nanoporous rock. Quartz is the dominant framework grain, and siderite is the dominant cement that affects flow zones. This study has demonstrated a robust approach to delineate flow units in the OW oilfield. We have developed a useful regional petrophysical reservoir rock flow zonation model for clastic reservoir sediments. This study has produced, for the first time, insights into the petrophysical properties of the OW oilfield from the Bredasdorp Basin South Africa, based on integration of core and mineralogy data. A novel sandstone reservoir zonation classification criteria developed from this study can be applied to other datasets of sandstone reservoirs with confidence.

show abstract

Determination of Reservoir Flow Units from Core Data: A Case Study of the Lower Cretaceous Sandstone Reservoirs, Western Bredasdorp Basin Offshore in South Africa

Cited by 17 publications

References 52 publications

Static reservoir modeling using stochastic method: a case study of the cretaceous sequence of Gamtoos Basin, Offshore, South Africa

Static reservoir modeling using stochastic method: a case study of the cretaceous sequence of Gamtoos Basin, Offshore, South Africa

Petrophysical Core-Based Zonation of An Oil Field In The Bredasdorp Basin South Africa

Petrophysical core-based zonation of OW oilfield in the Bredasdorp Basin South Africa

Contact Info

Product

Resources

About