Sharif Digital Repository

Producing from Gas Condensate Reservoirs under dew point pressure and at constant temperature may have a complex behavior because of existing two phase system and liquid around the well. Zones with different mobility generate as a zone away from the well containing only gas, a zone having liquid around the well and finally a zone with capillary effect. Existence of condensate around well reduces gas relative permeability and as a result productivity index of well decreases. In fact these condensate acts like an additional skin and because of some complex processes, investigating of these behaviors can be difficult.
Well testing analysis in Natural Fractured reservoir is generally based... 

Gravity drainage is known as the main mechanism for Enhanced Oil Recovery (EOR) in naturally fractured reservoirs. In fact, this mechanism is active in gas invaded zone. In spite of numerous researches in the area, the literature suffers from the lack of a comprehensive model for controlled gravity drainage. Calculating the accurate oil recovery and ultimate recovery factor is inevitable for a successful field development plan as well as enhancing oil recovery. To obtain the accurate values of the aforementioned parameters, an accurate model to solve nonlinear differential equations is necessary. To this end, COMSOL, the well known commercial CFD software, has been used for the modeling of... 

In this work, simulation of 3D three-phase naturally fractured reservoirs is studied. Both Dual Porosity and Dual Porosity-Dual Permeability models which are commonly used in commercial softwares such as ECLIPSE and CMG, are utilized. The governing equations include the mass (in Black-oil model) and linear momentum (in Darcy law form) equations, which are converted into pressure equations and a set of transport equations for the saturations and mole fractions of phases. These equations are solved once for the matrix domain and subsequently for the fracture domain. These two set of equations are coupled through transfer functions. The accuracy of computations significantly depends on how... 

Part1: Since conventional production has continued to fall, oil Production through EOR processes will supply an increasing percentage of the world’s oil demand in future years. Therefore; the importance of choosing the best recovery method becomes increasingly important to decrease the risk and find the best solution to the oil production decline from matured reservoirs. An expert system whose main task is to recommend the most appropriate EOR method will be described. The proposed expert system is utilized fuzzy logic system to screen four well known EOR methods of miscible 〖CO〗_2 injection, miscible HC gas injection, polymer flooding and steam injection based on reservoir and rock... 

It is common to inject gas in naturally fractured reservoirs to maintain the reservoir pressure. Recovery will be the result of the complex interplay of several mechanisms such as viscous flow, extraction by molecular diffusion, gravity drainage, oil swelling and capillary force. Generally the main mechanism is gravity drainage However in many cases like low permeability of matrix, small matrix block size and high capillary pressure; gravity drainage may be very low or ineffective. Low permeability results inefficient viscous displacement too. Therefore in these cases the main mechanism is diffusion. The parameters influences the diffusion are: The nature of the injected gas, the composition... 

Most of oil content, especially in Iran, has been reserved in fractured reservoirs, so study and modeling of production mechanism of these reservoirs are great of importance. Gravity drainage is one of these effective production mechanisms in fractured porous media which dynamic pore scale modeling of this mechanism will lead to better understanding of it. In this work, the effects of variety of parameters such as oil gravity, interfacial tension between oil and gas, pore and throat size distribution, fracture aperture, and block to block interaction (capillary continuity and reinfiltartion) have been investigated. So developed simulator in this work has two main and separated parts, which... 

Oil reservoirs, have integrated identity; that is they consist of different parameters such as wettablity, initial water saturation, capillary and gravity forces, etc. which are related to each other and affect ultimate recovery simultaneously. In fractured reservoirs, other parameters such as fractures and complex geological structures are also considered  among  important  parameters  which  affect  ultimate  recovery.  Due  to  large  amount  of reserves,  fractured  reservoirs  are  subject  to  different  studies  and  simulations.  In  this  research, different  parameters  which  affect  ultimate  recovery  in  fractured  reservoirs,  are  studied  and simulated. Different  studies ... 

Naturally fractured reservoirs are essentially very complicated; therefore we need a systematic and reliable characterization process in order to model, analyze displacement phenomena, simulate, develop, and schedule production and other engineering processes. These kinds of reservoirs have multi-scale asymmetry while there is no specific tool to fully characterize them, and on the other hand the field data (including stratigraphy, core study, well testing and seismology) have different resolutions and accuracies, though their significant role to investigate naturally fractured reservoirs. The objective of this project is to investigate the different data sources and present their... 

Due to the importance of enhanced oil recovery of heavy oil fractured reservoirs, in this work micromodel setup has been used to study the miscible solvent injection in five-spot fractured reservoirs with different fracture geometrical characteristics. Due to the visual nature and flexibility of the micromodel patterns it is a subject of interest to be used in different studies. Different patterns has been constructed by chemical etching and controlled laser etching and saturated with displaced fluid and flooded by constant rate injection of hydrocarbon solvent in abient temperature and pressure. At first, effect of fracture’s length, numbering, orientation, discontinuity and scattering on... 

Productivity reduction of oil and gas wells due to mud induced permeability impairment is one of challenging problems in drilling and production studies. This phenomenon is of prime importance in fractured reservoirs in which high permeability fracture networks act as conduits for feeding gas or oil from a tight matrix to the wellbore. Up to now, many experimental and modeling investigations have been done in formation damage in conventional reservoirs. But in spite of large contribution of fractured reservoirs in total hydrocarbon reserves, there is very little work reported in the literature investigating formation damage in such reservoirs. In this thesis, the effective parameters in... 

Gravity drainage is the self-propulsion of oil downward in the reservoir rock. Under favorable natural and operational conditions, it has been found to effect recoveries comparable to water displacement. With modern technical knowledge, the operator can often make a choice between dissolved gas drive, water drive and gravity drainage as the principal recovery agent in a reservoir. So far, gravity drainage has received less consideration than the other two. Gravity drainage is one of the most important processes taking place in fractured reservoirs and it plays a major role in oil recovery from low permeability matrix blocks during gas injection process. Gravity drainage is responsible for... 

Gravity Drainage and Capillary Imbibition are among the most important mechanisms in oil production from carbonate fractured reservoirs. In order to investigate the feasibility and effects of these mechanisms in oil recovery from carbonate cores, some different experiments were carried out at Sharif University Laboratories. Carbonate cores were taken away from the well-known Asmari outcrop, Asmari Mountain in south east of M.I.S. city and used in these experiments. Oil and gas samples were collected from field separators and recombined to reservoir composition. The Gas-Oil ratio was adjusted to obtain the reservoir fluid properties. A core flooding apparatus with various capabilities was... 

Free fall gravity drainage is one of the most effective mechanisms of producing the oil from the matrix blocks in the gas invaded zone of the naturally fractured reservoirs. Although several analytical models have been proposed to characterize this mechanism in a matrix block, but these models suffer from the practical or theoretical viewpoints. In this study, a new analytical model was presented to predict the oil production rate versus time from a homogeneous matrix block under free fall gravity drainage mechanism. The model was developed by considering the balance between involved forces in the gas-oil gravity drainage process. By simplifying the equation derived from the momentum... 

It is widely accepted that under reservoir conditions there exists some degree of block-to-block interaction that may lead to capillary continuity. The formation of liquid bridges causing capillary continuity between blocks will significantly affect the ultimate oil recovery. However, accurate modeling of the growth and detachment of traveling liquid bridges which causes capillary continuity between blocks remains a controversial topic. In this work the generalized continuity and momentum equations along with fracture capillary pressure are combined to develop a mechanistic model for formation of traveling liquid bridges between blocks. Firoozabadi and Ishimoto (1994) model is considered for... 

Gas condensate reservoirs show very complex behavior as wellbore pressure falls below the reservoir fluid dew point pressure and consequently liquid phase appears near the wellbore. Since pressure drawdown is the largest near the wellbore, therefore, this region is the first that experience the liquid dropouts. With continuing the production, reservoir pressures at the other parts of the reservoir fall below the dew point pressure and as a result, condensate appears at these regions. The more the condensate accumulates near the wellbore the more decreasing the gas relative permeability occurs. Condensate accumulating does as a liquid barrier and causes not only decreasing the gas production;... 

In water drive or waterflooded reservoirs, a significant amount of oil is remained in the reservoir as the residual oil. A process known as gas assisted gravity drainage, in its tertiary mode, has been applied in a number of conventional reservoirs to recover this residual oil. Gravity drainage is the main mechanism of oil recovery in the gas assisted gravity drainage enhanced oil recovery process. Previous investigations has shown that gravity force, spreading coefficient, three phase capillary pressure and reservoir wettability have significant effect on oil recovered via this process. The feasibility of using such a process in a naturally fractured reservoir is investigated in this work... 

Oil reservoir simulation serves an important role in forecasting oil production. This forecast, in turn, helps to devise a production scheme for hydrocarbon reservoirs which is one of main objectives of reservoir management team. In this research, using the idea of logarithmic distribution of reservoir fluid pressure around a wellbore, a new method for simulation of naturally fractured reservoir is developed. This method is shown to be more fast and accurate than conventional methods in reservoir simulation. In this method Dual-Porosity formulation is used for description of fluid flow in fractured reservoirs. The governing equations then were discretized by Galerkin Finite element method in... 

In This work, the performance of a finite volume (FV) numerical method is examined for simulating naturally fractured hydrocarbon reservoir. The dual-porosity approach applied for fracture modeling, and the flow transfer formulated based on a generalized black oil model which is based on matrix formulation, leading to a system of equations prone to degeneracy. This FV high-resolution central scheme numerical method is not sensitive to the choice of CFL number like some of other central schemes and can conveniently handle degenerate equations appearing in the reservoir simulation governing equation. In this effort, one dimension multi phase flow simulated in naturally fractured reservoir and... 

The main goal of petroleum reservoir simulation is finding of Pressure (P) and Saturation (S) of fluid in different places of prose media environment of the reservoir in a specific time interval. In this project we will implement a distributed reservoir simulator of a cluster. In fact parallelization of reservoir simulator is finding a method to decompose the reservoir domain into some region and assigning each region to a computer in a cluster of parallel computers in order to minimize the total amount of dependency of regions to each other and messages between nodes in the parallel network according to fluid equation in the system and finaly minimize' the duration of simulation. In this...