Vol 4, No 4 (2022)
Articles
Prospects of the oil and gas potential of the pre-Jurassic deposits of Southern Mangistau, the direction of further prospecting and exploration, and some issues of the methodology of their implementation
Abstract
In this paper, the authors present the features of the geological structure of the pre-Jurassic rock deposits of the Mangyshlak oil and gas complex. A brief analysis of the identified objects is given, prospects are determined, and proposals are given for the further direction of setting up prospecting and exploration work for oil and gas.
Kazakhstan journal for oil & gas industry. 2022;4(4):5-14
5-14
Peculiarities of identifying reservoirs with high radioactivity according to well logging data
Abstract
This article discusses the peculiarities of identifying reservoirs with high radioactivity based on geophysical research materials, the integrated approach used in interpreting research and analyzing geological and geophysical material using the example of Cretaceous and Jurassic deposits of the South Western Kamyshitovoye, Botakhan, Nuraly fields. The aim of the work is to study the distribution of highly radioactive productive reservoir rocks, substantiate the causes of their occurrence and the relationship with lithological differences of sedimentary facies.
Kazakhstan journal for oil & gas industry. 2022;4(4):15-31
15-31
Optimal number of Monte-Carlo simulations for hydrocarbon resources probabilistic estimation
Abstract
Background: Probabilistic resource estimation allows to assess the potential of oil and gas prospect, which is used for decision-making in the industry. The main result of the estimation is resource potential, expressed in probability distribution function of geological or recoverable hydrocarbon resources. Monte Carlo simulation commonly used for these purposes. It simulates the numerical value of the objective function. Aim: The aim of the work is to find the optimal number of Monte-Carlo simulations in the probabilistic resource estimation. Methods: Monte Carlo simulation is based on repeated calculation of the function describing the process using a random number generator. The function variable defined by statistical distributions is calculated using random number. Further, mathematical operations are performed on all variables of the function according to the mathematical model. Summarizing the obtained set of results, the statistical distribution describing the desired function is approximately estimated. Results: The accuracy of distribution function estimation increases with an increase of the number of simulations. However, this tend to increase the computation time. Thus, there is a choice between the speed and accuracy of the solution. The Latin hypercube reduces the influence of the random number generator imperfection, but intermediate calculations with Latin hypercube attenuate the decrease in the number of simulations compared to random sampling. Conclusion: Based on the results of the work, a logarithmic dependence of the calculation accuracy on the number of Monte Carlo simulations was obtained. In most cases, 10000 simulations with accuracy about 1% will be sufficient.
Kazakhstan journal for oil & gas industry. 2022;4(4):32-44
32-44
The indicator study role in determining path of motion of formation fluids in the development of a fractured reservoir field
Abstract
The high rate of oil production with the use of water flooding, complex geological and physical conditions of the carbonate reservoir of the deposit (fractures, faults) lead to progressive watering of the extracted products. The field has considerable oil reserves and is at the development stage II, the average water cut is more than 60%, most of the remaining reserves pass into reserves difficult to recover category. This article focuses on determining relations between blocks and practical application of the results of indicator study method in order to determine the porosity and permeability properties of fractured carbonate formations. According to this study method, the introduction of complementary technologies to improve the existing development system was proposed.
Kazakhstan journal for oil & gas industry. 2022;4(4):45-54
45-54
A pragmatic approach to polymer flooding to accelerate field implementation
Abstract
Background: Polymer flooding is a well-known enhanced oil recovery technique which can increase recovery factors in mature oilfields above 10% of the oil originally in place. Despite a lengthy history and many published field cases, the speed of deployment is still rather slow. With the need to boost energy production while minimizing energy wastes and carbon emissions, considering this technique known to reduce water usage and accelerate oil recovery should be a must. Aim: This short publication aims at providing guidelines to accelerate deployment of polymer injection in various oilfields and a couple of pragmatic approaches recognizing the need for field data instead of poorly constrained simulations or incomplete laboratory studies. Materials and methods: After a brief review of the technique and current implementation workflows, we will discuss new approaches to foster the deployment of injection pilots by showing how polymer injection can reduce emissions and energy wastes while accelerating oil production. Results: We provide a different perspective on polymer injection with pragmatic tools and ideas showing that going to the field fast provides more information than any laboratory study. Conclusion: Given the current need for mitigating oil production declines, polymer flooding is a technique of choice which can be deployed fast if basic criteria explained in this paper are met.
Kazakhstan journal for oil & gas industry. 2022;4(4):56-67
56-67
Research of the impact of switching to low- salinity water during polymer water flooding
Abstract
Background: Increasing the efficiency of a polymer flooding project, both technologically and economically, is always relevant. Aim: This paper aims to consider switching to less saline water as a fairly simple and effective way to increase the effectiveness of a polymer flooding project. Materials and methods: The work used data from a real polymer flooding project. Results: As a result, we have been able to significantly reduce polymer consumption and improve pumping efficiency. Conclusion: This work shows that, with the possibility of using less saline water, as a simple and effective way to reduce costs and increase efficiency, rolling polymer flooding.
Kazakhstan journal for oil & gas industry. 2022;4(4):68-77
68-77
Technology for increasing the oil recovery factor by reservoir stimulation by thermochemical methods
Abstract
Background: In the presented article, a composition is proposed that leads to the intensification and increase in oil production with an increase in temperature in the reservoir, as well as in the bottomhole zone. Aim: To study the improvement of methods for influencing deposits and bottom-hole zones of both production and injection wells, which allow completely displacing oil from the reservoir, as well as increasing oil production in general, thereby contributing to an increase in the final oil recovery factor of the reservoirs. Materials and methods: Based on laboratory studies, a new technology has been developed and a composition has been proposed, which includes a strong oxidizing agent, lower alcohols and trihydric alcohol, surfactants, etc. Results: The composition proposed for influencing the reservoir acts as follows: when the components of the composition interact, an exothermic reaction occurs, as a result of which a large amount of heat and gas is released in the bottomhole zone. Due to the released heat, heavy oil components are melted, deposited on the pore channels of the rock near the bottomhole zone and worsening the permeability of the bottomhole rock zone and reservoir injectivity. As a result of the impact of the composition, the permeability of the bottomhole zone and the injectivity of the injection well increase. Such an impact is also effective in that there is no loss of generated heat as a result of the exothermic reaction, and it directly affects the restoration of the permeability of the bottomhole formation zone and improves the rheological properties of oil. Conclusion: Conducted experiments have shown that, due to the effect of the proposed composition on clay rocks, clays do not swell, but, on the contrary, hydrophobization of the rock surface occurs due to clay compression, which prevents the subsequent negative impact of water on clay rocks. The reason for this incident is the acidic nature of the proposed composition. These properties of the proposed composition are a guarantee that its use in any formations (sandy, clayey, carbonate, dolomites, etc.) will be effective. Key words: bottomhole formation zone, permeability, strong oxidizing agent, lower alcohols, trihydric alcohol, surfactants.
Kazakhstan journal for oil & gas industry. 2022;4(4):78-89
78-89
Estimation of low salinity water flooding efficiency to improve oil recovery in sandstone reservoir in Kazakhstan
Abstract
Background: The regular increase in demand for hydrocarbons necessitates the introduction of optimal technologies to improve the development of reserves. The method of utilization of water with low salinity as an injected agent seemed promising in solving this issue. Aim: The aim of this article is to assess the potential of low-salt water to increase production and oil recovery in the terrigenous field of Kazakhstan. Materials and methods: For the study, low-salinity water injection into the reservoir was simulated on the ECLIPSE 100 simulator. The impact of salt concentration on production and oil displacement efficiency in the considered field during the secondary injection were determined by simulating flooding of solutions with different salinity. The model has been running for 18 years. Analysis of salinity reduction efficiency was carried out by comparing oil recovery after flooding with high salinity water. Results: The decrease in water salinity led to an increase in oil recovery by 1.3–2%. Such a slight increase in production is due to the initial hydrophilic properties of the rock. To obtain a response from the contact of low-salt water with rock, the presence of adsorbed oil on the surface of minerals is required. It can be said with high probability that in this reservoir, an increase in the oil recovery factor with a decrease in salinity is due to active interactions at the oil-water interface, one of which is an increase in viscoelastic properties. Conclusion: A slight difference in the efficiency of oil displacement between the studied low-salinity waters indicates the presence of the optimal salinity of the injected water. The initial hydrophilic property of the reservoir rock surface excludes wettability change as a reason for the increase in oil production. Further study of low-salt water flooding on core material from the studied field is recommended to obtain accurate data and understand how low salinity can affect the distribution of oil in the rock.
Kazakhstan journal for oil & gas industry. 2022;4(4):90-103
90-103
Synthetic polyampholytes based on acrylamide derivatives – new polymer for enhanced oil recovery
Abstract
Background: Due to its high efficiency, polymer flooding has been widely used in the fields of Kazakhstan. However, under conditions of high water salinity, high concentrations of polymers are needed to ensure the design viscosity of the solutions, therefore, polymers are needed that, at concentrations not exceeding 0.1–0.2%, will increase the viscosity of water up to 20–50 cP when the formation water salinity is above 200 g/ l. Aim: The purpose of this work is to study the salt- and heat-resistant properties of a linear polyampholyte based on acrylamide, an anionic monomer – sodium salt of 2-acrylamido-2-methyl-1-propanesulfonic acid - and a cationic monomer (3-acrylamidopropyl) trimethylammonium chloride and substantiate its applicability in oil production. Materials and methods: We used water with a salinity of 200–300 g/l, as well as oils with viscosities of 60, 138, and 420 cP. To simulate a porous medium, bulk sand models and aerated concrete with high porosity were chosen. Hydrolyzed polyacrylamide with a molecular weight of 17 million Da and a ternary polyampholyte with a molecular weight of 2.9 million Da were used as polymers. To compare the effectiveness of these polymers under conditions of high salinity, experiments were carried out to measure the dynamic viscosity and oil displacement efficiency. Results: It is shown that the injection of a 0.25% solution of triple polyampholyte dissolved in water with a salinity of 200 g/l into sand models increases the oil displacement efficiency by 23–28% compared to the injection of formation water. Under identical conditions, the injection of a hydrolyzed polyacrylamide solution resulted in an increase in the oil displacement efficiency by only 18%. Conclusion: Triple polyampholyte based on acrylamide derivatives has superior oil displacement properties compared to hydrolyzed polyacrylamide in high salinity reservoirs. The results of laboratory experiments can draw the attention of oil and gas industry specialists and subsoil users to new developments by the staff of the Institute of Polymer Materials and Technologies in terms of scaling up synthetic polyampholytes and conducting pilot tests.
Kazakhstan journal for oil & gas industry. 2022;4(4):104-116
104-116