Sharif Digital Repository

Water coning is a complex phenomenon that depends on various parameters which include among: production rate, matrix and fracture permeability, perforation interval, aquifer size, mobility ratio, capillary pressure, etc. Production of water can greatly affect the productivity of a well and the reservoir at large volume. In naturally fractured reservoirs, this problem is more complex because permeability of the fractures in the porous media is too high. With this complexity of water coning behavior in naturally fractured reservoir, this phenomenon was studied by simulating a sector of a carbonate fractured reservoir supported by an aquifer using Eclipse-300 simulator. A sector of an Iranian... 

Matrix acidizing as a well stimulation technique is performed to increase the production index by increasing the permeability and removing the formation damage in the near wellbore region. However, several challenges such as corrosion of the tubulars and iron precipitation in the formation are hindering this process. To encounter these challenges, different chemicals, or additives, such as corrosion inhibitors and iron control agents are added to the acid solution. Carbonate acidizing has been carried out using HCl-based stimulation fluids for decades. However, at high temperatures, HCl does not produce satisfactory results because of its fast reaction, acid penetration, and hence surface... 

There is increasing evidence that injecting modified brines has a significant impact on the amount of oil recovered, but the exact mechanism by which this occurs is an unsettled issue, and is supposed to be a cause of the complex interactions occurring between the phases insitu. In this thesis, surface chemistry of smart water has been investigated. Fluid/solid and fluid/fluid interactions for Bangestan crude oil in tfhe presence of designed solutions and a set of dilutions of Persian Gulf seawater have been studied and compared. Fluid/solid interactions were investigated through wettability studies. Impact of salinity and ionic composition on this interaction was measured through contact... 

The purpose of this study was to investigate the experimental and modeling of the drop formation process on calcite rock and calcite aged in nano fluid surfaces in order to analyze size dependent contact angle and wettability modification. To do this, the calcite surfaces were prepared by cutting to an approximately size of 3*3*0.4 cm and grinded and polished to achieve different roughnesses. The purity and roughness of the samples were determined by X-ray diffraction and atomic force microscopy, respectively. In order to conduct the dynamic and static contact angle measurements on the calcite surface in vapor saturated condition, a small laboratory device was designed. The advanced contact... 

Matrix acidizing aims at bypassing near wellbore damages in typical carbonate reservoirs or enhancing permeability and hydraulic conductivity in naturally fracture ones. The simulation of acidizing process at pore scale and complex geometries by LBM will lead to gain more knowledge about molecular mechanisms that govern rock dissolution, diffusion and advection of reactive fluid and help the evaluation of acidizing efficiency.In this thesis, simulation of acidizing includes the following steps:
• Multicomponent fluid convection
• Fluid diffusion into the solid
• Fluid-rock reaction
• Boundary conditions including periodic, bounceback, non-equilibrium bounceback, Dirichlet,... 

Polymer flooding is a famous enhanced oil recovery method and is used to reduce mobility ratio of displacing fluid to displaced fluid by forming a stable front in displacing process. Due to high costs, polymer flooding faces economical risks and from this point of view, performance investigation of polymer flooding in laboratory scale was concerned. In this project, performance of 7 types of polymers which have different rheological properties were investigated in fractured/non-fractured carbonated and sandstone reservoirs. These polymers consists of 4 commercial polymers, one branched polymer, one synthetic polymer and one polymer composite which have different molecular weight,... 

By continuous decreasing the fossil fuel energy resources and increasing demand of such energies on the other hand with decreasing exploration of the new ones, production from these limited resources are in grate consideration. As a few percentages of the oil recovers by primary oil production and also remaining a lot of oil after water and gas injection in the secondary oil recovery process, causes that new methods to increase the oil recovery has been proposed. Water injection is a simple and common method in enhanced oil recovery process. Also water alternating gas injection and simultaneous water and gas injection causes considerable increase in oil recovery. Recently utilization of... 

One of the most common methods for determining elastic moduli of rocks and porosity is acoustic velocity log. The elastic moduli of reservoir rock are widely used in geomechanical modelling, borehole stability and hydraulic fracture design. Carbonate oil reservoirs are known for heterogeneity and anisotropic nature. Therefore correlation of acoustic velocity and rock properties are generally challenging. Rock’s shear modulus is very important during saturating of sample with pore fluid because assumed it is independent of pore fluid type. However due to the several fluid-solid interaction mechanisms such as velocity dispersion, surface energy reduction and viscous coupling, shear modulus... 

In this project, some issues facing the application of AVO in carbonate reservoirs were studied,reviewed and discussed: physical relationships between elastic and reservoir rock properties to estimate compressional and shear wave velocities both on core measurements and well logging data, sensitivity analysis for Gassmann‐Biot and Kuster‐Toksoz rock physics models on the representative carbonate samples, lithology discrimination and reservoir characterization in carbonate intervals using AVO seismic attributes and specifically LambdaRho‐MuRho approach.The studied area (Azadegan Oil Field) is an area about 1174 km2 of 3D seismic data and was containing of six wells in the time of study. In... 

The most fundamental concept in considering electrical properties of reservoir rocks are formation Resistivity factor and Resistivity index which are defined by Archie and are useful in interpretation of well logging, evaluation of porosity and saturation. A theory on the relationship between formation resistivity factor and porosity, also resistivity index and saturation are presented by use of parameters Cementation factor and Saturation exponent. The Archie equation is valid only when the rock is strongly water-wet and clay free, which is not the case in carbonate rocks. Therefore the Archie equation cannot be generalized over the entire carbonate reservoirs. On the other hand influence... 

Carbonate matrix acidizing using hydrochloric acid which causes CO2 generation is one of the most popular well stimulation techniques in recent decades. Lots of the wormhole propagation models developed for laboratory scale, assumes that the cores are fully saturated with aqueous solution and no CO2 gas is produced. Final purpose of this research is to develop a geochemical model describing equilibrium composition of a 3 phase system of acidic solution-gas-rock accurately in common pressure and temperature conditions of carbonate matrix acidizing to obtain main inputs of acid reactive flow in porous media from it. In this regard, concept of the “extent of the reaction” is defined and after... 

Well stimulation techniques are used to increase the productivity of oil and gas wells. One of the effective well stimulation methods, is matrix acidizing. During matrix acidizing, acidic solution is injected into the formation at pressure below the formation fracture pressure. Most of the time, acid needs to be reached to low permeability layers for more efficient damage removal. Divertors are used for diverting acid from high permeability to low permeability layers.Successful performance of a viscoelastic acid during an acid job, is highly dependent on the surfactant rheological properties. For a betaine viscoelastic surfactant, we have studied the effect of different parameters on the... 

One of the best stimulation methods for oil and gas wells is matrix acidizing in order to increase the near wellbore permeability. in acidizing, good acid coverage in different layers is one the main goals. so, various methods have been presented. important part in using these methods is to not damage formation and economic matters. modern methods utilize VES acids for this purpose. viscoelastic characteristics of these materials by formation of miscellaneous, increases the apparent viscosity by a large degree. for this reason, VES fluids can be used to improve acid divergence in acid injection operation. acid system based on viscoelastic surfactants that is changed to gel instantly, can be... 

At each stages of oil and gas production, from the time of drilling of the wells to the state of production and development of the reservoirs, formation damage would hinders the oil/gas rate and causes high pressure drop in the drainage area. To eliminate the damage caused by the formation blockage, several remediation techniques are used, which are called well stimulation methods. The most common method for the past tens of years is matrix acidizing which lead to the improvement of the performance of the well. To optimize this operation, optimal acidizing design is needed, otherwise the acidizing process face failure and lead to blocking of the well through acid-induced damage. One of the... 

Matrix acidizing operation is one of the popular methods of well stimulation in the oil and gas industry which is used to remove near wellbore damage, increase the permeability, hence improve the production rate from the formation. Hydrochloric acid is used in the carbonate reservoirs to remove formation damage and create wormhole deep in the rock. It has been shown that with the proper operating design, significant improvement in the production rate can be obtained. A successful acid operations involves the proper selection of the candidate wells, identify the type of formation damage, stimulation method selection, correct design acidizing scenario, implementation of the technique and... 

Formation acidizing is one of the best well stimulation methods to remove reservoir damage and improve recovery of oil and gas well. The proper design of acidizing operations can significantly improve the production of a formation. In the meantime, causing formation damage and precipitation in oil flowlines, which may be caused by the incompatibility of the stimulation fluid with the reservoir fluid and rocks, is one of the most serious problems in the operation, which reduces permeability and oil/gas production. As a result, the success of the acidizing operation requires to study the interaction of components of operation (acid, reservoir water, formation rock, and acid additive)... 

Reactive flow through porous media is a phenomenon of high importance in various study subjects i.e. groundwater, mining, geology, and petroleum reservoirs. In petroleum engineering, a related topic to this phenomenon is the dissolution of the rock matrix due to acidizing. Near_wellbore carbonate rock acidizing has been used for decades in the petroleum industry to enhance the productivity of the well. Optimal injection rate is a key question in such operations. Various models have been used to simulate reactive flow in porous media many of which are continuum-scale that face significant uncertainty regarding the pore-scale nature of the flow, mass transfer, reaction, and subsequent changes... 

Acidizing is one of the common methods of stimulating the well to remove formation damage and Skin factor. In carbonate reservoirs, hydrochloric acid creates permeable channels called wormholes due to the reaction with the porous medium. Previous researches have studied the effect of the main rock and fluid parameters (temperature, pressure, type and concentration of acid and rock lithology) at the core scale. However, wellbore scale will different from core scale due to the difference in the wormhole density, the flow geometry, the amount of acid leakage from wormhole wall and competition. Very limited models predict these effects for large scales. In this research, the geometry of linear...