Sharif Digital Repository

The primary purpose of acidizing operations in the oil and gas industry is to enhance hydrocarbon production. Acidizing has been a common and conventional method for years, especially when production engineers face issues like declining reservoir pressure leading to reduced production rates. Initially, the treatment solution is referred to as matrix acidizing. In acidizing operations, different additives are combined with the acid to control its behavior in the reservoir. These additives may include iron control agents, corrosion inhibitors, friction reducers, and more. Incompatibility among these additives, the acid, and reservoir fluids can lead to severe damage to the reservoir.... 

Formation damage is probable to occur while drilling, work-over operations, and well completion in near wellbore zone due to different reasons; which leads to excess pressure drop through this area. Well stimulation operations are proposed to remove these damages and improve oil production; among which, acidizing is known as a traditional applicable method to stimulate oil and gas wells. Although this approach is accepted and chosen as a well stimulation method to remove formation damages, its poor design and implementation results in new formation damages. One of these arises when acid contacts asphaltic oil, which causes asphaltene particle instability and asphaltic sludge rapid... 

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... 

Matrix acidizing treatment are performed to enhance the permeability of oil and gas formations by removing pore plug. Numerous additives have been introduced to aid the penetration of the acid or to perform other important tasks. To be able to pump the reactive fluid from the surface through the tubing and into the formation, corrosion inhibitors usually is necessary to protect the metal from attack by the fluid itself. In this work the Henna extract introduced as a pre flush additive and corrosion inhibitor in acidizing operation. It also enters the formation and effect on the matrix permeability and acidizing performance. The effect of Henna extract on permeability of rock will be... 

The acid fracturing process is a thermal, hydraulic, mechanical, geochemical and geomechanical coupled phenomena in which the behavior of these variables are interrelated. To model the flow behavior of an acid into a fracture, mass and momentum balance equations are used to draw 3D velocity and pressure profiles. Part of the fluid diffuses or leaks off into the fracture walls and dissolves part of the fracture face.An acid balance equation is used to draw the concentration profile of the acid and to account for the quantity of rock dissolved. An algorithm is developed for this process to generate the final conductivity distribution after fracture closure. The objective of modeling acid... 

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,... 

The acidizing operations have significant impact on productivity and production of oil and gas wells, so that wells having shell or regional damage are good candidates for well stimulation operations which could result in significant increase for efficiency or injectivity. Generally, the neural networks are nonlinear learning mathematical systems. In this project consists, At first, wellhead data of acidizing operation are collected in two Gachsaran oil field (38 wells) and Nar and Kangan gas field (35 wells). Generally, the neural networks are nonlinear learning mathematical systems. In the neural Network by using two algorithms, back propagation algorithm and Quick Propagation algorithm... 

In many cases, oil and gas extraction from reservoirs due to damage and permeability reduction near wellbore is lower than optimum level and reduces the flow of oil into the well. In fact, formation damage is the collapse of natural condition of reservoirs, In addition to delaying production and increasing costs, it causes early desertification of wells. Well stimulation methods are used to solve this problem and increase production. One of the most effective ways to increase the production of wells is well acidizing. In this study, the acid performance of the fractured carbonate reservoirs has been investigated. In this type of reservoirs, due to the existence of high permeable paths of the... 

In this work, an improved model for simulating carbonate core acidizing, with the ability of correctly modeling fluid diversion in dual-core experiments is created based on an existing two-scale continuum model. The improvements are applied on the momentum transfer equation, continuity equation, pore-scale structure-property relations and fluid rheology model. Also a more realistic injection scenario and geometry configuration are presented for simulating the diversion experiments. The Darcy-Brinkman-Stokes equation is implemented instead of Darcy’s equation and the continuity equation is modified by adding the mass source term. A global rheology model is developed capable of capturing exact... 

Acidizing is one of the widely used practices of formation damage remediation. The success of this rather expensive job depends on the precise design and operation. Though, improper execution of an acid job, not only does not improve the formation damage but also can contribute to even more damage itself. For this purpose, it is critically important to thoroughly design an acidizing job conducting extensive lab experiments and utilizing numerical tools before operation in order for a successful acidizing. Unlike, carbonate acidizing, the chemistry of sandstone acidizing is very complex and challenging because of the wide variety of minerals and aqueous species present in the system. Hence, a... 

Acidizing operation is performed in oil and gas reservoirs with the aim of overcoming formation damages, increasing permeability and reducing skin factor. In carbonate reservoir, the hydrochloric acid increases the permeability of the areas around the well to a more than its initial value by dissolving part of the formation minerals. Considering that most of Iran's oil and gas reservoirs are in the category of carbonate reservoirs, it is important to study the reaction kinetics of carbonate minerals and acids used in acidizing operation. The complex and multifactorial nature of the acidizing operation in the reservoirs has made it very difficult to design a successful and optimal operation.... 

The Oil wells are usually damaged because of the drilling process and production scenarios or fluid injection during EOR processes. These damages would critically affect the rate of production and injectivity of the well in the form of plugging damage. Different methods are used to fix these damages and increase the production flow from the oil wells. One of the most widely used well-stimulation methods to remediate this challenge is well acidizing. Although this method has very high efficiency in improving the ability of wells, if it is not designed and implemented correctly and optimally, it can cause induced damage and even lead to the well shutting. This challenge is especially reported... 

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... 

The process of injecting acid or acidizing, is one of the most common ways to stimulate oil and gas wells. The purpose of this process is to increase the productivity of the well by increasing the permeability of the reservoir rock around the well. This is especially important in carbonate reservoirs due to damage to the formation and low intrinsic permeability in some places. In order to minimize the effects of structural damage, conventional wormhole channels are created to pass through the injured area. One of the important factors in acid validation is achieving optimal injection rate, which means obtaining the highest permeability with the lowest amount of injected acid.Numerous... 

Today, acidizing is one of the most important methods for stimulation and increasing the productivity of oil and gas wells. In Iran and other oil-rich countries, a large amount of money is invested every year in acidizing operations. Due to complex nature of acidizing of an oil formation, it’s very difficult to design an optimized and successful operation. Therefore, many research projects have been performed for understanding the physics of the dissolution of reservoir rock by acid and the behavior of wormholes and secondary reactions. The most important prerequisite of these researches is the perfect knowledge of acid and mineral reaction kinetics. One of the most common experiments to... 

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...