Sharif Digital Repository

The vapor extraction process (or VAPEX) uses vaporized solvents injected into a horizontal well to form a vapor chamber within the reservoir. Vapor dissolves in the oil and enhances the oil production by decreasing the oil viscosity in heavy oil reservoirs. To evaluate the process we conduct a simulation study on an Iranian heavy oil reservoir called Kuh-e-Mond. In addition, a semi-analytical investigation of the VAPEX process has been performed. The idea is to perform VAPEX simulation for a laboratory model and find a methodology to compare the results of the simulator with the semi-analytical Butler's model. In particular, a semi-analytical dimensionless correlation for production rate... 

Steam-assisted gravity drainage is one of the most promising strategies to develop huge heavy oil and bitumen accumulations. Like the other thermal processes, this method aims at reducing oil viscosity by increasing the temperature. But in an economical point of view, it requires a great volume of steam for injection. Moreover, early breakthrough of steam and high steam-oil ratio makes it uneconomical, especially in long production time. In this study, a new method, two wells cyclical steam-assisted gravity drainage is compared with a conventional steam-assisted gravity drainage process. Well configuration in two wells cyclical steam-assisted gravity drainage is the same as the... 

In offshore Iran, wellbore instability is quite common and the main cause for most of problems during drilling operations. In this study, the existing relevant logs, drilling and other data from offset well were analyzed and integrated to construct a precise Mechanical Earth Model (MEM) describing pore pressure, stress magnitudes and orientation, and formation mechanical properties of the South Pars Gas field. Then, the constructed MEM was refined and calibrated using the existing caliper, image logs, rock mechanical core test and drilling data and through history matching to constrain and reduce the uncertainties associated with limitations and availability of the existing data. Using the... 

Steam injection process has been considered for a long time as an effective method to exploit heavy oil resources. Over the last decades, Steam Assisted Gravity Drainage (SAGD) has been proved as one of the best steam injection methods for recovery of unconventional oil resources. Recently, Fast-SAGD, a modification of the SAGD process, makes use of additional single horizontal wells alongside the SAGD well pair to expand the steam chamber laterally. This method uses fewer wells and reduces the operational cost compared to a SAGD operation requiring paired parallel wells one above the other. The efficiency of this new method in naturally fractured reservoir is not well understood.... 

Many bitumen reservoirs contain shale layers of varying thickness, lateral extent, and frequency. These shale layers, depending on their size, vertical and horizontal locations, and continuity throughout the reservoir, may act as a flow barrier and severely reduce vertical permeability of the pay zone and slow down the steam-assisted gravity drainage steam chamber development. Therefore, to improve productivity in these reservoirs, understanding of the effects of reservoir heterogeneities has become necessary. This work presents numerical investigation of the effects of shale barriers on steam-assisted gravity drainage performance when applied to produce mobile heavy oil. The most concern of... 

The vapor extraction process (or VAPEX) uses vaporized solvents injected into a horizontal well to form a vapor chamber within the reservoir. Vapor dissolves in the oil and enhances the oil production by decreasing the oil viscosity in heavy oil reservoirs. To evaluate the process we conduct a simulation study on an Iranian heavy oil reservoir called Kuh-e-Mond. In addition, a semi-analytical investigation of the VAPEX process has been performed. The idea is to perform VAPEX simulation for a laboratory model and find a methodology to compare the results of the simulator with the semi-analytical Butler's model. In particular, a semi-analytical dimensionless correlation for production rate... 

The particle shape is an important factor playing critical role in evaluation of the interactions between particles in high-concentration particle-fluid flows. In this paper, the well-known multisphere (MS) approximation approach and the novel rolling resistance approach are utilized to examine their performance in order to simplify the generalized shaped particle’s interactions within the framework of discrete element method (DEM) and computational fluid dynamics (CFD). The performance of two approaches are compared with the perfect particle’s shape geometry, for the limited cases of cubic-shaped and disk-shaped particle flows in a horizontal well drilling process as a reference scenario.... 

Increasing cuttings bed height is a serious concern during extended-reach well drilling. In order to predict and prevent cuttings bed height increase, it is essential to study how the critical parameters influence the cuttings transport, especially the drill pipe rotation effects on the cuttings transport process. In conventional models for cuttings transport, the dynamic behavior of particles due to drill pipe rotation is neglected or empirically simplified. This paper presents a coupled Computational Fluid Dynamics and Discrete Element Method (CFD-DEM) approach to simulate the cuttings transport considering the dynamic collision process. The fluid phase is treated as an Eulerian continuum... 

Production logging is used to evaluate wells production performance. Interpretation of production log data provides velocity profile and contribution of each zone on total production. In multi-phase flow conditions, production log interpretation can be challenging since producing fluids do not have similar densities and travel with different speed depending on fluids properties and wellbore deviation. Production log interpretation in multi-phase producing wells requires identifying downhole flow regimes and determining velocity profile for each phase. There are different flow regimes and velocity models available, which are being used in production log interpretation to determine wells flow... 

In this work, studies of underground gas storage (UGS) were performed on a partially depleted, naturally fractured gas reservoir through compositional simulation. Reservoir dynamic model was calibrated by history matching of about 20 years of researvoir production. Effects of fracture parameters, i.e. fracture shape factor, fracture permeability and porosity were studied. Results showed that distribution of fracture density affects flow and production of water, but not that of gas, through porous medium. However, due to high mobility of gas, the gas production and reservoir average pressure are insensitive to fracture shape factor. Also, it was found that uniform fracture permeability... 

The accurate and precise computational models in order to predict the hole cleaning process is one of the helpful assets in drilling industries. Besides the bulk properties such as the flow velocity, particles average size, cleaning fluid properties, etc., that will affect the cleaning process, there is an unanswered question about the microscopic properties of the particles, particularly those which determines the contact characteristics: Do those play a major role or not? The rudimentary answer is not. The first purpose of the present work is to answer this question via a developed computational fluid dynamics coupled with discrete element method (CFD–DEM) in which the six unknown rolling... 

In this paper, the impact of three parameters including nanoparticles geometry, particles aggregation and borehole inclination on induced formation damage from water based drilling fluids were investigated by means of experimental studies. Accordingly, we designed a dynamic filtration setup capable to rotate and change well inclination. Nano-based drilling fluids consisting of spherical, cubical and tubular shapes nanoparticles as fluid loss additives were used. Mud cake quality, core permeability impairment and degree of formation damage at various well inclinations were examined. The cluster structure of aggregated particles were determined using fractal theory and applying dynamic light... 

Estimating available hydrocarbon to be produced during secondary oil recovery is an ongoing activity in field development. The primary plan is normally scheduled during early stage of field's life through master development plan studies. During this period, due to the lake of certain data, estimation of the field efficiency is usually based on rules of thumb and not detailed field characterization. Hence, there is a great motivation to produce simpler physically-based methodologies. The minimum necessity inputs of percolation approach make it a useful tool for foration performance prediction. This approach enables us to attain a better assessment of the efficiency of secondary recovery... 

In this paper, the impact of three parameters including nanoparticles geometry, particles aggregation and borehole inclination on induced formation damage from water based drilling fluids were investigated by means of experimental studies. Accordingly, we designed a dynamic filtration setup capable to rotate and change well inclination. Nano-based drilling fluids consisting of spherical, cubical and tubular shapes nanoparticles as fluid loss additives were used. Mud cake quality, core permeability impairment and degree of formation damage at various well inclinations were examined. The cluster structure of aggregated particles were determined using fractal theory and applying dynamic light... 

The present study examined the effect of nanoparticle size and geometry on filter cake buildup during dynamic filtration using experimental and modeling approaches. A dynamic filtration setup was proposed and designed to test cross-flow circulation against a synthetic core at a constant differential pressure. The proposed mathematical model considers the critical deposition boundary of the porous media for particles along with drag, lift, friction, buoyancy, permeate, and electrostatic forces. The comprehensive model response allowed investigation of the aggregation and shape of nanoparticles at different cross-flow inclinations. The drag and lift force coefficients and moment of inertia of... 

The particle shape is an important factor playing critical role in evaluation of the interactions between particles in high-concentration particle-fluid flows. In this paper, the well-known multisphere (MS) approximation approach and the novel rolling resistance approach are utilized to examine their performance in order to simplify the generalized shaped particle’s interactions within the framework of discrete element method (DEM) and computational fluid dynamics (CFD). The performance of two approaches are compared with the perfect particle’s shape geometry, for the limited cases of cubic-shaped and disk-shaped particle flows in a horizontal well drilling process as a reference scenario.... 

There are several types of drilling methods to increase the productivity of a well, such as horizontal drilling, extended reach horizontal drilling and Multilateral (ML) drilling. It is thought that ML wells could be more economic with higher productivities than horizontal or extended reach horizontal wells. Advances in ML drilling promise reduced costs, greater flexibility and increased profit potential. In the last 20 years, thousands of ML wells have been drilled worldwide, but only a small percentage of the total number of wells is multilateral. The probable reason may be lack of concise information and misconceptions surrounding the costs and perceived risks. However, recent advances in...