Mathematical modelling of enhanced gas production

Abstract Based on a mathematical model for 2D filtration of a two-phase multicomponent hydrocarbon mixture, the boundary problem of optimizing distribution of well flow rates was for the first time composed and solved so as to maximize the gas recovery from a natural gas reservoir at its final stage of development. The input data used in the model are the planned gas production in the reservoir and reservoir characteristics (its thickness, porosity, and permeability). The flow rate optimization in individual wells is carried out in such a way that the pressure drop is kept constant for the recharge area of each well. The proposed optimization algorithm takes into account both the restriction on the flow rates in certain wells and their shutoffs for remedial maintenance. The own computer program has been developed to solve the problem. The efficiency of this approach is illustrated by the example of the natural gas reservoir Kotelevske (Ukraine). It is shown that the control of the pressure equalizing process in the recharge area of each well leads to the decrease in differential pressure inside the whole reservoir. As a result, the 6% increase in gas production was possible for the optimum alternative in a shorter period of time

Synthesis of High-effective Steel Corrosion Inhibitors in Water-oil Mixtures

It is a relevant and practically important task for environmental protection to devise effective means to protect metals against corrosion in aggressive media containing water, petroleum products, carbolic acids, and mineral salts. To stop corrosion, corrosion inhibitors are used that must be constantly improved and whose composition must be properly adjusted. The main drawback of the highly effective inhibitors based on alkyl imidazolines, a mixture of alkyl imidazolines with alkyl pyridinium and/or quaternary ammonium compounds soluble in a methanol medium, is their high prices at relatively significant consumption in the corrosive environment. This paper reports the synthesis of steel corrosion inhibitors in oil-containing aqueous environments that meet the stricter ecological and economic requirements. It has been shown that increasing the level of water mineralization improves the corrosive activity of aqueous environments relative to unalloyed steels. The presence of carbon dioxide, hydrogen sulfide, or carboxylic acids leads to the oxidation of water-oil mixtures resulting in the increased rate of steel corrosion. We have studied the effectiveness of the synthesized inhibitors based on oil and polyethylene polyamines containing imidazolines. At a temperature of 80 °C, the mixture that contained 200 cm3of a 3 % sodium chloride solution, 800 cm3of oil, and at the concentration of acetic acid of 0.5 and 3.0 g/dm3 at the inhibitor dose of 50 mg/dm3, has reached the degree of protection of steel against corrosion at the level of 90–92 %. Based on a full factorial experiment, the regression equation has been derived that makes it possible to easily enough calculate an optimal dose of the steel corrosion inhibitor in water-oil mixtures. It has been shown that the synthesized inhibitor shows prospects for protecting metals against corrosion both in the mineralized waters containing oil and in the presence of petroleum products containing wate

TECHNOLOGY of the Comprehensive Desalination of Wastewater From Mines

The issue of desalination is relevant for many countries of the world; the most promising technology for demineralization appears to be membrane technology. The stabilizing treatment of water before feeding it to the membrane filters involved the ion exchange softening of the solution based on the weakly acidic cation exchanger DOWEX MAC-3 in the H+ and Na+ forms. This makes it possible to improve the efficiency of baromembrane desalination and the service time of membranes. The nanofiltration membrane OPMN-P ensures the purification of low mineralized waters from sulfates (by 74–93 %) and hardness ions (67–90 %); at the same time, the membrane has low selectivity in terms of bicarbonate anions and does not retain chlorides. This avoids the accumulation of these in the concentrates at the nanofiltration purification of low mineralized waters. The inverse osmotic membrane Filmtec TW30-1812-50 shows selectivity for sulfates and hardness ions of over 99 %. The selectivity for chlorides is 83–94 % for low mineralized water, and 90–95 % for highly mineralized water. The concentrates contain hardness ions, sulfates, chlorides, and bicarbonate anions in significant concentrations. We have defined conditions for the effective softening of the formed concentrates at the comprehensive treatment by lime and aluminum coagulants. When desalinizing the concentrate of low- and highly mineralized waters, the sulfate concentration decreased to 2.55–6.53 mg-equiv./dm3 and 3.31–9.02 mg-equiv./dm3, respectively. At the same time, the concentration of hardness ions was 3.31–9.02 mg-equiv./dm3 and 4.20–10.65 mg-equiv./dm3. Creating comprehensive technologies for the purification of mineralized waters makes it possible to ensure the proper efficiency of water desalination and to utilize the waste formed with obtaining useful products. That could reduce anthropogenic pressure on the environment and solve the problem of freshwater shortage for people and industr