англ тэк

hydrocarbons in previously-discovered fields (discovered in the SPE classification, and classes 1 to 8 in the NPD classification).

The concept of reserves, as used in most of the Western classification schemes, does not fully correspond to the Russian term запасы (reserves). The Western term reserves is closer to the Russian concept of «reserves in the well drainage area'', which is not included in either classification scheme Therefore, in Western classifications, criteria for defining reserves are more rigid than those for explored reserves in the Russian classification scheme, e. g. for distinguishing the С 1 category.

Resource classifications applied by market economy countries primarily take into account technological and commercial factors, which may influence resource estimates,, In the Russian classification, the factors used to define resource and reserves categories are the degree of geological exploration of the accumulation, and the methodology for defining calculation parameters, which has an indirect bearing on the estimate's reliability. The Russian classification does not provide for commercial factors, and neither does it include categories for hydrocarbons which can be recovered by enhanced recovery methods. Therefore, the Russian classification would allocate reserves to a relatively high C1 category on the basis of geological indications when the distance between appraisal wells is several times the distance between future producers whereas classifications applied in the USA would define such reserves as only probable.

The Russian classification scheme takes into account technological factors and the degree of reservoir exploration (including parameters such as variations in lithology and reservoir properties, the physical properties of the reservoir fluids, well productivity, etc.). These factors make it possible to identify the most efficient production system, the commercially-justified production period, and the most efficient recovery technology.

In the Russian scheme, the oil recovery ratio is determined by a series of technical and technological calculations which pay due regard to the future application of enhanced recovery methods. The Western classifications are based on a different approach to reserves calculation and stock taking. Reserves which could be recovered by

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secondary (or tertiary) production methods are considered as proved only when those methods are already applied. In the USA, such an approach can result in only the Low Estimate being registered for a new field, whose reserves then gradually grow in time as enhanced recovery measures are introduced. Correspondingly, the general recovery factor for initial «proved» reserves continues to grow for the entire country. Therefore, due to the presence of geological, technical and commercial (and sometimes legal) limitations, the «proved» reserves (in for example the SEC classification) only constitute a proportion of the entire volume of discovered recoverable oil, which could be produced if there were no such limitations.

Studies by a group of experts in the Russian State Commission for Reserves (GKZ) for a selection of 290 accumulations in 50 fields in Western Siberia demonstrated that the proved reserves category corresponds to 95-100 % of the sum of Russian reserves categories А, В and C1. The C1 category relates to 70-75 % of the proved reserves. Likewise, an audit for the Russian oil major Yukos showed that proved reserves correspond to 73 % of categories А, В and C1, and that proved + probable reserves cover 90 % of categories А, В and C1.

Reserves analyses for Lukoil indicate that estimates of oil-in- place are practically equal. Depending on the number of wells and on the geological and physical parameters of accumulations, if commercial factors are not taken into consideration, then 93-98 % of the reserves can be considered as «proved», of which 70-75 % belong to the C1 category. An estimate of the proved reserves (which cover proved producing, proved non-producing, and proved undeveloped) performed by Miller & Lents with due regard to production profitability in Russia, equaled 75 % of А, В and C1 categories.

Some of the reserves groups do not have direct analogies in the Russian classification scheme, but corresponding classes can be found in other official documents pertaining to reserves stocktaking. For example, analogies for reserve groups 1, 2, 3, 4, 5, 6 in the NPD classification can be found in the Russian standard statis-

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tical reporting form (known as form 6-GR), and the following categories can be distinguished:

Group 1 or producing reserves, where at least one of the basic hydrocarbons (oil or gas) is being produced;

Groups 2 and 3 reserves which are prepared for commercial development, comprising reserves for which a production license has been obtained but production has not been started as development of the field is not completed;

Groups 4 and 5 reserves which are in appraisal, referring to discoveries where appraisal work is in progress in compliance with a license, or where appraisal work is planned but the license has not yet been obtained. These groups also cover unlicensed fields where appraisal has been suspended for various reasons but which may be offered for licensing in the future;

Group 6 reserves are «in conservation», and apply to fields where appraisal or production has been suspended.

It should be noted that the Western classification schemes used by Governments and oil companies make extensive use of probabilistic methods. Quantitative estimates of the reliability of reserves and resources evaluations constitute the basis of risk assessment and risk management by an investment company, and for the preparation of long-term resource management strategies by Governmental bodies.

We believe that there is a need for a new Russian classification scheme, one which makes use of both the best aspects of the current Russian scheme and the modern evaluation methods which have been developed in other countries. The introduction of probabilistic methods of reserves calculations would allow for a more reasonable resource management policy, with clearer license terms and a more efficient tax regime which would take into account all the exploration and development risks of a project. The introduction of probabilistic methods would also stimulate the wider application of seismic techniques in commercial reserves assessments, which would help to reduce the costs of exploration and development drilling.

However, probabilistic methods should not entirely replace traditional deterministic estimates but should merely supplement

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and build on them. It is also important that a transition to a new resource classification scheme in Russia does not conflict with the compilation and preservation of the State Registry of oil and gas reserves.

Table 1. Oil and gas reserves and resources categories in the Russian classification scheme

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Table 3

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Only recoverable reserves and resources are classified, oil inplace is not included. Reserves cover classes 1, 2, 3 and 4.

III. Переведите устно

РОССИЙСКИЙ И МЕЖДУНАРОДНЫЙ ОПЫТ КЛАССИФИКАЦИИ ЗАПАСОВ И РЕСУРСОВ НЕФТИ И ГАЗА

Классификация запасов и ресурсов устанавливает следующие принципы подсчета, оценки достоверности и учета запасов и ресурсов для решения широкого крута задач планирования и управления минерально-сырьевой базой:

–определение стратегии освоения ресурсов отдельных регионов и страны в целом;

–прогнозирование уровней добычи на дальнюю перспективу (на 10-15 лет);

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–проектирование геологоразведочных работ на нефть и газ;

–принятие решений об инвестировании работ по освоению конкретного месторождения.

Поэтому вопросы совершенствования методики классификации запасов и ресурсов всегда являлись актуальными как в России, так и в других нефтедобывающих странах.

В нефтяной промышленности зарубежных стран используется несколько разных по своему назначению классификаций запасов и классификации заинтересованных государственных органов, нефтяных компаний, научных обществ, институтов и биржи по ценным бумагам.

Все эти классификации имеют много сходных элементов, поэтому в последние годы большое внимание уделяется проблеме не просто сопоставления различных систем классификации запасов и ресурсов нефти и газа, но и разработке универсальной классификации.

В России, в отличие от большинства зарубежных стран, действует единственная, утвержденная государством, классификация запасов.

Но и в России проявляют большой интерес к проблеме разработки универсальной классификации запасов и ресурсов нефти и газа и сопоставлению российской классификации запасов с принятыми в нефтедобывающих странах.

Это связано с тем, что, с одной стороны, ряд российских нефтяных и газовых компаний (ЛУКОЙЛ, ЮКОС, ГАЗПРОМ и др.) для привлечения инвестиций вынуждены проводить оценку своих запасов месторождений по западным стандартам.

С другой стороны, западные компании, которые ведут геологоразведочные работы и разработку месторождений нефти и газа на территории России, пытаются перевести принятую

вРоссии систему классификации на привычные для них термины и определения.

IV. Переведите письменно

Временная классификация запасов и ресурсов нефти и газа, принятая в России

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но оцененные (C2). Ресурсы нефти и газа по степени обоснованности подразделяются на перспективные (Сз), прогнозные

локализованные (Di\) и прогнозные (D, и D2).

В основу выделения категорий положены требования к степени изученности месторождения и достоверности оценки запасов и ресурсов. Причем степень достоверности оценки запасов и ресурсов определяется не количественно, как это делается, например, в технических науках (т. е. указанием границ, в которых может находиться значение запасов нефти, удовлетворяющее требованиям к классу а задается перечислением требований, определяющих принадлежность запасов к той или иной категории. В отличие от принятых за рубежом правил подсчета и учета запасов в российской классификации категорийность определяется как для геологических, так и для извлекаемых запасов.

V. Прочтите текст и объясните англоязычному коллеге разницу между российской и норвежской системами классификации запасов и ресурсов.

Важной особенностью используемой в России классификации запасов является ее привязка к стадийности геологоразведочных работ на нефть и газ (табл. 1).

Таблица 1 Характеристика категорий запасов и ресурсов нефти и газа

в российской классификации

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На основе разведанных запасов (категории А, В и С1) проектируют разработку и определяют уровни добычи нефти и газа на разведанных и разрабатываемых месторождениях.

Предварительно оцененные запасы (категория С2) определяют перспективы месторождения в целом и на их основе планируют геологоразведочные работы по доизучению залежей нефти и газа.

Перспективные ресурсы (категория Сз) нефти и газа используются при планировании поисковых и разведочных работ и прироста запасов категорий С1 и С2-

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