Kazakhstan journal for oil & gas industry

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.

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.

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.

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.

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.