EXTENDED ABSTRACT

Introduction

The optimization of hydrocarbon resources in the world is considered as a basic goal and the first step in this direction is reservoirs evaluation. Having a plan in exploiting the country's oil reservoirs to increase the productivity and age of the wells is one of the important things that the lack of attention is felt in the country's oil industry. Considering the country's oil situation and the many years that have passed since the first oil wells were drilled in Iran, the move on to maintenance production will have significant effects in securing national interests.
The goal of this study is to optimize hydrocarbon resources through advanced 3D modeling techniques, which will ultimately help conserve energy and improve resource management. In principle, using 3D modeling in hydrocarbon reservoirs can improve the efficiency of extraction and use of hydrocarbon resources, as a result of which waste is minimized and sustainable practices of energy can be expanded.
Hydrocarbon reservoir modeling has a special place in order to predict production and optimize it, predict reservoir behavior and manage production. In fact, modeling is the best technique for linking and relating data collected from wells and fields. Presenting an accurate and suitable model of a reservoir with the aim of predicting the characteristics of the reservoir before carrying out exploitation and production operations in order to determine the production and productivity of the reservoir fluid and how the fluid moves inside it, the number and appropriate location of the wells required for optimal production from the reservoir and in general to have an economic view in order to optimize the production and operation of the reservoir in such a way that in addition to the maintenance of the reservoir and increasing the recycling rate from that reservoir, it also provides a logical answer for investment affordable and also economical.
Today, 3D reservoir simulation is considered one of the common studies in all major oil companies and has become an essential part of routine exploration and production activities. To overcome the limitation inherent in 2D studies, it is necessary to define 3D data and models. The three-dimensional simulation of geological phenomena provides the possibility of collecting all available data for a certain project in a single model, which can be used to analyze the data in the software environment.
Maintenance production of oil fields requires the study of the production behavior of the field over time. Accurate evaluation of the natural characteristics of the reservoir and investigation of the behavior of similar reservoirs in other parts of the world, designing mathematical models of the reservoir for simulation in order to achieve the optimal production pattern, using these models to predict the reaction of the reservoir to the production process over time, are among the necessary conditions for Designing appropriate methods to improve the recycling rate. Therefore, the comprehensive study of the reservoirs begins at the same time as their exploitation begins and continues until the end of the life of the reservoirs. The management of non-renewable hydrocarbon resources makes it necessary to optimize exploitation methods, and the first step in this direction is to describe reservoirs in order to evaluate them, which plays a decisive role in reservoir management.

Materials and methods
Current specialized software makes it possible to model complex and irregular geological buildings in three dimensions, which is done by using geological maps and building information to build a correct model. The effectiveness of modeling in the evaluation of oil reservoirs for reservoir studies has been proven and includes many cases of reservoir description. Reservoir description includes description of pore spaces and grain size, reservoir thickness, reservoir porosity and permeability, identification of facies and sedimentary environment.
Accordingly, the modeling of hydrocarbon reservoirs is one of the most important studies and also considering the quantity and variety of data in the model, it is one of the most challenging discussions in oil companies. This knowledge generally covers a part of the oil industry's needs in field study and development. For this purpose, several softwares have been designed that perform the modeling process with high accuracy by using geostatistical methods. Among the modeling software, we can mention the three-dimensional geological modeling software, which in the present study, the Ilam reservoir formation and the petrophysical parameters of this reservoir are modeled by Petrel software.
For using more benefits reservoir modeling performs to recognize more the geometry of oil traps and reservoire management. Generally, this technique is an essential part of oil industry in the fields of study and development processes. Softwares are planning for this aim to process of modeling by using geostatistic technique with high resolution such as 3D geological modeling (petrel).

Results and discussion
In this study to provid the reservoir 3D structural and petrophysical modling were used petrophysical evaluation logs of 6 vertical and 2 horisontal wells and UGC maps together in one of oil fields that located of Abadan plain. Ilam reservoir in the studied field is divided to several zones based on various petrophysical characteristics that after making the 3D griding and petrophysical modling, distribution maps of petrophysical properties such as porosity, water saturation and net to gross thickness N/G were constructed.
The values related to water saturation and porosity have been calculated by applying the reservoir grade (N/G) based on Phie>0.045 and Swe<0.56. After the reservoir properties are modeled, in the next step, volume calculations are performed based on the prepared models. In order to perform volume calculations, water saturation models, porosity, net to gross ratio, volume coefficient of oil and gas, depth of water and oil contact surface and depth of oil and gas contact surface are used.

The calculation relationships used are as follows:

Bulk Volume = Total Rock Volume
Net Volume = Bulk Volume * Net/Gross
Pore Volume = Bulk Volume * Net/Gross * Porosity
HCPV oil = Bulk Volume * Net/Gross * Porosity * So
HCPV gas = Bulk Volume * Net/Gross * Porosity * Sg
STOOIP = HCPV oil/Bo + (HCPV gas/Bg) * OGR gas
GIIP = HCPV gas/Bg + (HCPV oil/Bo) * GOR oil
Recoverable Oil = STOOIP * RF oil
Recoverable Gas = GIIP * RF gas

These evidences suggeted that studied zones of Ilam reservoir of this region have different reservoir qualification and main Ilam zone is considered reservoir zone because of better permeability and porosity and also suitable water saturation, Thus, the porosity of 19-20%, water saturation of 32% are the reasons for the most reservoir quality of this zone. The oil volume of Ilam Formation in studied field has estimated by volumetric calculation method 1886.1 million barrels. Finally the results obtained in this study will help in the planning of drilling future wells in the field.
The results of this research show the adoption of innovative technologies in the optimization of hydrocarbon resources, which causes a change towards more efficient and environmentally responsible practices.

Conclusion
The use of advanced 3D modeling techniques in optimizing hydrocarbon resources significantly improves extraction efficiency and resource management while minimizing waste. These techniques not only enhance hydrocarbon extraction but also contribute to the development of sustainable, environmentally responsible practices in the energy sector. In this study, the Ilam Formation was evaluated petrophysically and divided into different zones based on key parameters such as porosity, permeability, water saturation, and net-to-gross ratio. The main zone of the Ilam Formation exhibited the highest reservoir quality, with a porosity of 19-20% and water saturation of 32%, making it optimal for hydrocarbon extraction. Volumetric calculations estimated the oil-in-place volume to be 1,866.1 million barrels, providing valuable insights for future drilling and extraction planning. These findings highlight the importance of advanced modeling in enhancing resource utilization and supporting more efficient, environmentally sustainable practices in hydrocarbon management.