The exacerbation of the world ecological situation related to the global climate warm-up gave an impulse to the environmental activity of the gas industry at all levels. Scientific and technical, production, organisational and legal.
Due to diversification of technological processes and spacious geographical location of RAO Gazprom facilities in this country the industry's atmospheric emissions contain a wide spectrum of climatically active components (methane, carbon oxides, nitrogen oxides, volatile organic compounds), Table 1.
The main volumes fall on emissions of CO2 and CH4. Given the potential global climate warm-up methane emissions are the most harmful.
And so in the ecological policy approved by the special ordinance of the RAO Gazprom Board of 14 April, 1995 one of the high priority tests was development and implementation of measures on decreasing of the natural gas (methane) losses in the process of its recovery and transmission.
At present a far-reaching discussion on the issue of qualitative assessment of volumes of methane discharched into atmosphere by the RAO Gazprom facilities is going on.
Different authors publish rather contradictory data according to which the methane discharged into atmosphere by the RAO Gazprom facilities accounts for 2.5 – 8 percent of the total gas recovered.
In the first national report, prepared by the Interdepartmental commission of Russian Federation on the climate change issues, the authropogenic emission of CH4 in the process of recovery, transmission and consumption of natural and associated gas in 1995 defmed as 16mt (4% of the total recovered). If was also pointed out that the uncertainty of the assessment is rather great.
One of the most available methods of assessment of methane discharges into atmosphere for the RAO Gazprom facilities is the balance one.
For instance the material balance of the main pipeline gas transmission consists of the following items:
Q= Qcon+Qon Qugs DQ+Qlos
were
Q-volume of gas entering into the pipelines, m3; Qcon-volume of gas supplied to consumer, m3;
Qon-gas used for own needs, m3;
Qugs- (*) gas withdrawal, (-) injection into underground storages, m3;
DQ-change of gas volume in the pipeline system for the estimated period, m3;
Qlos-losses of gas in the process of gas transmission by through the main pipeline, m3.
Two items of the material balance ("losses" and "gas used for own needs") are directly connected with methane atmospheric emissions. Gas used as fuel for gas pumping units (power expenditure, and gas directly entering atmosphere during various technological operations at compressor stations and the pipeline (technological expenditures) and emergency discharges before closing valves and cutting off the damaged section.
The above differentiation is not mandatory for the industry statistic records which significantly impedes evaluation by the balance method of volumes of methane entering atmosphere. The balance item "Zones" which is defined by the volumes of unplanned methane emissions into air has a direct bearing on the emissions into atmosphere.
Using results of the material balance analysis of the period 1990–1996 the authors have ascertained that the balance items coursing methane emission into atmosphere account for not more than 2% of the total gas recovery.
All assessments exceeding this level are groundless reckless and should not be taken into account.
It should be noted that the balance assessment of the industry methane emissions on a scale of 2% of the total gas recovered in a formal index of a highest possible volume of methane emission.
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