English abstract
The petroleum industry profoundly influences hydrocarbon reservoir production and the economy. Al Shomou Field, situated in the southern
part of Oman, is associated with a crude oil of low gravity of approximately 48◦American Petroleum Institute gravity (API) The primary reservoir,
Athel Silicilyte, is located at a depth of 4Km and comprises 90% silica. Athel
Silicilyte known as a tight reservoir featuring a porosity of 40% and a permeability
of 0.02mD. Hydraulic fracturing is employed as a development technique to
enhance field production. This study aims to developed a mechanical stratigraphy
of the Athel Formation with using of existing logs, such as porosity, resistivity,
density, gamma-ray and permeability. As well as, to create a rock physics model
for identifying the pore aspect ratio, create a facies log based on core data, and
characterize the Athel reservoir by examining geomechanical properties such as
Poisson’s ratio and Young’s modulus. The main data sources for this project include wireline logs, drilling parameters, natural fracture interpretation, radioactive
tracer data, and information on perforation intervals.
The project comprises three distinct workflows. The first workflow involves
constructing a rock physics model and generating plots using the Xu-Payne 2009
methodology and is categorized into three sections. A rock physics log has been
developed, and subsequently, the pore aspect ratio model has been refined. In the
second workflow, three core wells were analyzed to identify different facies, which
were then used to create log facies using six Machine Learning algorithms known as
Support Vector Machine (SVM), Gaussian Process Classification (GPC), Random
Forest Classifier (RFC), Neural Network Classifier (NNC), K-Nearest- Neighbors
(KNN) and Decision Tree Classifier (DT). The pore aspect ratio process provided
a more comprehensive understanding of the reservoir’s pore spaces system. The
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rock physics model of eight drilling wells used in the study indicates a porosity
range of 0.05% to 0.30%, with velocity values ranging from 3km/s to 5km/s. The
pores within the formation exhibit cracked shapes, as observed in the rock physics
model. In contrast, the rock physics model derived from tracer data shows a
narrower porosity range of 0.15% to 0.25%. The pore aspect ratio log provides
further insights into the Athel formation, dividing it into five distinct units. Utilizing the facies log and geomechanics log, which includes Poisson’s ratio and
Young’s modulus, eight different facies have been identified within the formation.
These facies categorize and characterize the different lithological variations and
properties observed within the Athel reservoir.
