Effect of reservoir heterogeneities on elastic and seismic properties of Lower Cretaceous Sand Intervals, Lower Indus Basin of Pakistan

The Pab Formation of Zamzama block, lying in the Lower Indus Basin of Pakistan, is a prominent gas-producing sand reservoir. The optimized production is limited by water encroachment in producing wells, thus it is required to distinguish the gas-sand facies from the remainder of the wet sands and shales for additional drilling zones. An approach is adopted based on a relation between petrophysical and elastic properties to characterize the prospect locations. Petro-elastic models for the identified facies are generated to discriminate lithologies in their elastic ranges. Several elastic properties, including p-impedance (11,600-12,100 m/s*g/cc), s-impedance (7,000-7,330 m/s*g/cc), and Vp/Vs ratio (1.57-1.62), are calculated from the simultaneous prestack seismic inversion, allowing the identification of gas sands in the field. Furthermore, inverted elastic attributes and well-based lithologies are incorporated into the Bayesian framework to evaluate the probability of gas sands. To better determine reservoir quality, bulk volumes of PHIE and clay are estimated using elastic volumes trained on well logs employing Probabilistic Neural Networking (PNN), which effectively handles heterogeneity effects. The results showed that the channelized gas-sands passing through existing well locations exhibited reduced clay content and maximum effective porosities of 9%, confirming the reservoir's good quality. Such approaches can be widely implemented in producing fields to completely assess litho-facies and achieve maximum production with minimal risk.

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An Assessment of the Pakistan Water Apportionment Accord of 1991

Resources ◽

10.3390/resources8030120 ◽

2019 ◽

Vol 8 (3) ◽

pp. 120 ◽

Cited By ~ 4

Author(s):

Hassan ◽

Burian ◽

Bano ◽

Ahmed ◽

Arfan ◽

...

Keyword(s):

Climate Adaptation ◽

Water Security ◽

Assessment Tools ◽

Indus Basin ◽

Management Policy ◽

Indus River ◽

Rabi Season ◽

Lower Indus Basin ◽

Indus Delta ◽

Important Field

The Water Apportionment Accord (WAA) of Pakistan was instituted in 1991 to allocate Indus River water among Pakistan’s provinces. This paper assesses the performance of the WAA in terms of the accord’s ability to meet the barrages’ and environmental demands in the Lower Indus Basin. Use of metrics as assessment tools in water security and climate adaptation is an important field, with the potential to inform sustainable management policy. Reliability, resiliency, and vulnerability are used as indicators to define the system’s performance against supply. The results indicate from the pre-Accord period to the post-Accord period, the reliability of Guddu Barrage (the upstream-most barrage in the study) is not changed. However, at Sukkur and Kotri, the most downstream barrage in the study, reliability has significantly decreased. The Results reveal the high vulnerability of the Indus delta in Rabi season when the flows decline and the majority of the water at the Kotri Barrage is diverted.

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An integrated analysis of mineralogical and microstructural characteristics and petrophysical properties of carbonate rocks in the lower Indus Basin, Pakistan

Open Geosciences ◽

10.1515/geo-2019-0088 ◽

2019 ◽

Vol 11 (1) ◽

pp. 1151-1167

Author(s):

Waheed Ali Abro ◽

Abdul Majeed Shar ◽

Kun Sang Lee ◽

Asad Ali Narejo

Keyword(s):

Thin Section ◽

Carbonate Rocks ◽

Carbonate Rock ◽

Indus Basin ◽

Reservoir Quality ◽

Data Sets ◽

Petrophysical Properties ◽

X Ray ◽

Lower Indus Basin

Abstract Carbonate rocks are believed to be proven hydrocarbon reservoirs and are found in various basins of Pakistan including Lower Indus Basin. The carbonate rock intervals of the Jakkher Group from Paleocene to Oligocene age are distributed in south-western part of Lower Indus Basin of Pakistan. However, there are limited published petrophysical data sets on these carbonate rocks and are essential for field development and risk reduction. To fill this knowledge gap, this study is mainly established to collect the comprehensive high quality data sets on petrophysical properties of carbonate rocks along with their mineralogy and microstructure. Additionally, the study assesses the impact of diagenesis on quality of the unconventional tight carbonate resources. Experimental techniques include Scanning Electronic Microscopy (SEM), Energy-Dispersive X-ray Spectroscopy (EDS), and X-ray diffraction (XRD), photomicrography, Helium porosity and steady state gas permeability. Results revealed that the porosity was in range of 2.12 to 8.5% with an average value of 4.5% and the permeability was ranging from 0.013 to 5.8mD. Thin section study, SEM-EDS, and XRD analyses revealed that the samples mostly contain carbon (C), calcium (Ca), and magnesium (Mg) as dominant elemental components.The main carbonate components observed were calcite, dolomite, micrite, Ferron mud, bioclasts and intermixes of clay minerals and cementing materials. The analysis shows that: 1) the permeability and porosity cross plot, the permeability and slippage factor values cross plots appears to be scattered, which showed weaker correlation that was the reflection of carbonate rock heterogeneity. 2) The permeability and clay mineralogy cross plots have resulted in poor correlation in these carbonate samples. 3) Several diagenetic processes had influenced the quality of carbonates of Jakkher Group, such as pore dissolution, calcification, cementation, and compaction. 4) Reservoir quality was mainly affected by inter-mixing of clay, cementation, presence of micrite muds, grain compactions, and overburden stresses that all lead these carbonate reservoirs to ultra-tight reservoirs and are considered to be of very poor quality. 5) SEM and thin section observations shows incidence of micro-fractures and pore dissolution tended to improve reservoir quality.

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Porosity prediction of lower cretaceous unconventional resource play, south Indus Basin, Pakistan, using the seismic spectral decomposition technique

Arabian Journal of Geosciences ◽

10.1007/s12517-018-3566-7 ◽

2018 ◽

Vol 11 (10) ◽

Cited By ~ 5

Author(s):

Muhammad Tayyab Naseer ◽

Shazia Asim

Keyword(s):

Lower Cretaceous ◽

Spectral Decomposition ◽

Indus Basin ◽

Decomposition Technique ◽

Unconventional Resource

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Unconventional Reservoir characterization and Sensitive Attributes Determination: A Case Study of Eastern Sembar Formation, Lower Indus Basin, Pakistan

Geophysics ◽

10.1190/geo2018-0761.1 ◽

2020 ◽

pp. 1-67

Author(s):

Muhammad Abid ◽

Liping Niu ◽

Jiqiang Ma ◽

Jianhua Geng

Keyword(s):

Organic Matter ◽

Seismic Data ◽

Wave Impedance ◽

P Wave ◽

Indus Basin ◽

Brittleness Index ◽

Poor Correlation ◽

Unconventional Reservoir ◽

Geomechanical Properties ◽

Lower Indus Basin

The Sembar Shale formation in Lower Indus Basin Pakistan is thought to contain significant potential of unconventional resources; however, no detailed study has yet been carried out to quantify its potential. In conventional oil and gas exploration, reservoir rocks have been the main focus therefore, limited number of wells target the Sembar Formation. To explore its regional view, the seismic characterization of these shale is required. Generally, a poor correlation is generally observed between P-wave impedance and the reservoir and geomechanical properties of rocks, making it challenging to characterize them using seismic data. We present a workflow for characterizing the seismic derived unconventional prospect of the Sembar Shale using prestack seismic data along with well logs. The logging results of the two wells show that organic matter richness of well A is in high to very high values while, well B is in low to very low values. Considering the mineral composition and brittleness index evaluation the Sembar Shale in well A is brittle to less brittle in nature. The organic content, porosity, and brittleness index results in well A makes the Lower Cretaceous Sembar Formation favorable to be considered as a potential organic shale reservoir. Four sensitive attributes, derived through integration of the rock petrophysical, geochemical and geomechanical parameters, are correlated with P-wave impedance. The correlation of each sensitive attribute has been applied to characterize the Sembar Shale potential. These attributes are first-order indicators to depict organic matter, porosity and geomechanical properties. This attribute approach is further validated through rock physics modeling. The workflow presented in this study can be employed to assess unconventional reservoir potential of the Sembar Formation in other parts of the basin.

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