Table Of ContentImproved Techniques
for the Extraction of
Primary Forms of Energy
Improved
Techniques
for the
Extraction of
Primary Forms
Energy
of
A Seminar of the
United Nations Economic Commission for Europe
(Vienna 10-14 November 1980)
Published in co-operation with the
United Nations by
Graham & Trotman Limited
Published in 1983 by
Graham & Trotman Umited
Sterling House
66 Wilton Road
London SWI V 1D E
in co-operation with the United Nations
© The United Nations 1983
Softcover reprint of the hardcover 1s t edition 1983
ISBN-13: 978-94-009-6651-2 e-ISBN-13: 978-94-009-6649-9
001: 10.1007/978-94-009-6649-9
British Ubrary cataloguing In Publication Data
Improved techniques for the extraction of primary forms of energy.
1. Fossil fuels - Congresses
I. United Nations. Economic CommiSSion for Europe
662'.6 TP318
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v
TABLE OF CONTENTS
1. Improved techniques for the extraction of primary forms of energy:
A general overview p.l
2. Introduction; conclusions and recommendations for further international
co-operation p.2?
3. Consolidated reports on:
The role of "Increased efficiency in the extraction of primary forms
of energy" within national energy and research and development policies -
Hydrocarbons; by W.J. Schmidt (Austria), general rapporteur p.43
The role of "Increased efficiency in the extraction of primary forms of
energy" within national energy and research and development policies -
Solid fuels; by G.B. Fettweis (Austria), general rapporteur p.SO
Progress and trends in the development of conventional technologies for
the extraction of primary forms of energy - Hydrocarbons; by
V. Pominov (USSR), general rapporteur p.66
Progress and trends in the development of conventional technologies for
the extraction of primary forms of energy - Solid fuels; by
A. Szczurowski (Poland), general rapporteur p.??
The prospects of using improved and newly developed techniques for
exploiting alternative energy sources as a substitute for conventional
fossil fuels; by G. Pusch (Federal Republic of Germany), general
rapporteur p.84
Prospects of new techniques designed for the exploitation of hydrocarbon
resources; by X. Boy de la Tour and H. Le Leuch (France), general
rapporteurs p.98
Experience in and opportunities for developing international co-operation
in the field of improved fossil fuel extraction techniques; by ECE
secretariat, general rapporteur p.126
vi
4. Summary of national papers (35):
Improved Resource Recovery in Coal Mining - A Global OVerview, by A.K. Ghose p.133
Enhanced Oil Recovery Techniques: State of the Art and Potential,
by G.L. Chierici p.134
Recovery of Combustible Material from Spoil Heaps, by J. Medaets p.136
Main Trends in Research and Development in Belgium Collieries, by H. van Duyse p.138
Consolidation of Coal and Strata with Polyurethane in Long-wall, by F. Meyer p.139
Recovery of Fuels from Spoil Heaps in the Bassin du Nord and Pas-de-Calais
Collieries, by M. Devos p.14l
Open-cast Coal Mining in France, by C. Badey p.143
Special Aspects of Underground Coal Gasification in western Europe, by U. Krauss p.145
Limits of Output from fully Mechanized Longwalls, by W. Sikora p.146
Surface Mining in Oil-Sands, by W. Durst p.148
Ways and Means to Achieve Higher Recovery of the Deposits in the Lignite Mines
of the Koflach District in the Alps, by C. Lukasczyk p.150
Economic Mining of the Lignite Deposit Zangtal Unterfloz as Example for
Mastering Difficult Geological Conditions in the Alps, by F. Kailbauer p.152
Tertiary Recovery by CO Flooding in Hungarian Fields, by S. Doleschall and
2
J. Torok p.154
working the Warwickshire Thick Coal, by D. Drake p.156
The Feasibility of Increasing the Recovery Factor from the Nagylengyel Deposit
in Hungary by Tertiary Oil Recovery Using Ammonia Injection, by A. Ban,
v. B~lint, S. Nagy and F. Pach p.15?
Recovery of Tip Coal in the South Wales Coalfield, by J.J. Davies p.159
Effective Development of Coal Winning in Bulgaria, by V. Zanchev, V. Zherov and
D. Aleksandrov p.160
Exploitation of Coal Deposits under Hazardous Conditions, by J. Matuszewski p.162
Exploitation of Crude Oil and Natural Gas Reservoirs in Poland, by C. Jaracz p.164
Mining of Safety Pillars in Poland as a Rational Element of Energy Reserves
Management, by Z. Bojarski p.166
Legal Aspects of the Mineral Deposits Economy, by W. Naglik p.16?
vii
Improved Economic Method for the Utilization of wastes from Coal Extraction in
poland, by B. Herniczek p.169
Status and Further Development of Fracturing Deep and Low-Permeable Gas
Reservoirs, by F. Brinkman p.l?l
Experience in Sour Gas Production from Depth of 6,000 m, by J. Moritz p.l?2
The Importance of Geological Features in Designing Open-Pit Lignite Exploitations,
by J. Tznakakis p.l?3
The Belgian-German Project for Deep Underground Gasification, by P. Ledent p.l?5
Taking Up and Analysing Workings and Figures for the Evaluation of Functional
Interdependences and their Use for Computer-Based Research and Technical/
Economical Improvements of Conventional Tunneling Operations at Collieries in
the Ruhr-District, by H.N. Schachter and F.L. Wilke p.l?6
Improvement of Methods of Extracting and Refining Oil Shales and their Technical
and Economic Evaluation, by A.V. Khorkov p.l??
Underground Coal Gasification in the USSR, by the Government of the Union of
Soviet Socialist Republics p.l?9
Economic Conditions for the Production of Hydrocarbon Feedstock from Bituminous
Rocks and Oil Shales, by K.I. Mangushev p.18l
Economic and Technical Problems of Raising the Oil Recovery Factor of Seams
in the USSR, by V.A. Kleshchev and E.D. Mukharsky p.183
The Economic Possibilities of Exploiting the World's Non-Conventional Resources
of Natural Hydrocarbons, by A.K. Arsky p.185
Increased Productivity by Improved Cutting Technology, by A. Zitz and M. Sigott p.l,
Status of Work on the Extraction of Bitumens, by L.I. Morozov p.189
Oxidizing Processes, by Y.P. Zheltov p.190
4. List of Contributors p.193
1
IMPROVED TECHNIQUES FOR THE EXTRACTION OF PRIMARY FORMS OF ENERGY:
A GENERAL OVERVIEW
INTRODUCTION
Enhanced recovery techniques for conventional and non-conventional fossil energy
forms constitute a significant option for any energy policy aiming at satisfying
long-term demand and careful exploitation of finite resources. The related supply
potential is quite large for all fossil fuels, however it appears of particular
relevance with respect to oil. At present, the efficiency of extraction techniques
of fossil fuels is. still low: average world recovery is about 30 per cent of the
resources in place in the case of oil and 60 to 80 per cent in the case of natural
gas and coal. The scope for improvement has now become more evident as energy
prices inc.rease and extraction technologies make progress.
On the basis of these considerations, the Senior Advisers to ECE Governments on
upon invitation of the Government of Austria, decided to convene a Seminar
~nergy,
under the title "Seminar on Improved Techniques for the Bxtraction of Primary Forms
of Energy". It was held at Vienna from 10 to 14 November 1980. The Seminar
brought together for the first time within the ECE framework approximately one
hundred experts of the coal, oil and gas industries from 16 member countries.
About 40 different technical reports were presented as well as 7 consolidated
reports in relation to each topic of the Seminar.
The Seminar was to provide an insight into the various recovery techniques for all
kinds of fossil fuels, their cost and effectiveness and to explore the possibilities
for increasing co-operation in this particular field. It should assess the state
of art and the technical, economic and environmental difficulties for the develop
ment and application of conventional and advanced extraction technologies;
determine the contribution of improved extraction technologies for the reduction
of energy supply problems in coming years; and identify areas where international
co-operation would prompt a widespread application of these techniques and thereby
a more efficient utilization of the conventional and unconventional fossil fuel
resources in the ECE region.
The Seminar concentrated on four topic areas:
1. The role of "Increased Efficiency" in the extraction of primary forms of
energy within national energy and R&D policies;
2
2. Progress and trends in the development of conventional technologies for
the extraction of primary forms of energy
(a) the case of hydrocarbons
(b) the case of solid fuels
3. New extraction techniques applicable in particularly difficult natural
circumstances or to certain forms of non-conventional energy (heavy oils,
oil shales, tar sands ••• )
(a) the case of hydrocarbons
(b) the case of solid fuels
4. Experience and opportunities for developing international co-operation in
the field of energy extraction techniques.
The conclusions and recommendations of the Seminar (ECE/SEM.4/2) were adopted by
the Senior Advisers to ECE Governments on Energy at their third session in February
1981. This report prepared by an ad hoc group of experts summarizes the most
important findings of the Seminar.
A. CONVENTIONAL TECHNIQUES
(a) The case of hydrocarbons
(i) The problem of classification
While 17 countries out of ECE's 34 members produce hydrocarbons, only 3 of them
produce more crude oil and natural gas than their own consumption. It is therefore
a logical consequence that intensive exploration and exploitation prevails in
almost all countries in order to improve recovery.
A clear classification of oil extraction methods does not exist. A distinction
is, however, made between:
Primary methods: using the energy generated in the deposit, including
fracturing, chemical treatment of the well bore, mechanical pumping and
gas-lift.
Secondary methods: including ordinary steam water CO and other gas
2
injection.
Tertiary methods: including other thermal (i.e. in situ combustion) and
chemical processes as well as injection of miscible gases.
The Seminar distinguished between "conventional" and "unconventional" extraction
methods. "Conventional" methods comprise mainly primary and secondary methods in
addition to techniques for positioning, drilling and well equipment. The importance
of conventional methods as a group is very great. Only 2 and 6 per cent of the
petroleum currently extracted in the USSR and in the USA respectively is produced
by "unconventional methods". By the year 2000, they would contribute by 6 and 10
per cent of the production in these two countries. At the world level the share
of conventional methods is still higher. Estimates of reserves should not be
limited therefore to proven, probable and possible categories only, but should also
show primary, secondary and tertiary reserves. Of course, within such groups,
proven, probable and possible reserves could be shown separately. In some cases,
especially if tertiary reserves are concerned, "prospective" or "speculative"
reserves should be estimated.
(ii) The various techniques
The .contribution of any given recovery technique to raising production depends
largely on:
an accurate estimate of the reserves in place, which is difficult to obtain
in the initial stage of oil field development and production;
the recovery factor the calculation of which may require many years of
observations;
the impact of any other recovery technique which may, and usually is, applied
as well.
These factors being interdependent, it is very difficult to determine the compara
tive importance of the various recovery techniques. Nevertheless, it would seem
that among conventional methods, water flooding of oil fields is of key importance.
It is suitable for fields where the viscosity of oil does not exceed that of water
by more than 10-12 times. The efficiency of water flooding systems depends on the
reservoir characteristics, the timing of its application, the space configuration
of the field drilling, and pressure and rate of water injected. Pilot tests in the
field after the absolutely necessary laboratory tests have proven to be valuable.
They make optimization of water injection possible as concerns the best timing,
divergent views exist. In the USSR, water injection is employed often as soon as
the field starts production, but this, in the opinion of other experts, might
preclude in various cases the successful application of certain tertiary methods
such as miscible gas injection.
Experts attributed a growing role to in fill drilling of wells, but recognized that
depending on drilling costs, there was no optimal well spacing pattern or optimal
well density for all fields.
As for the recovery factor of natural gas fields which is already higher than the
one of oil fields, possibilities of increasing recovery are more limited. Host of
the applied extraction techniques relat to the improvement of the permeability of
the near-well zone by chemical treatment and fracturing. Particular difficulties
also arose when drilling down to very deep gas strata in central Europe. Doubling
of the recoverable prospective reserves is expected world-wide through treatment
of low permeable reservoirs. Massive hydraulic frac is the possible treatment to
be applied. It is understood that costs for such a stimulation could well reach
the amount of drilling costs.
A comparison of recovery factors for oil and gas fields in the various countries
has proven essential differences. These differences are due to geological,
methodical and historical factors. It is of interest to mention that old reservoirs
in the USA, those which were produced between 1900 and 1950 - and on account of the
recovery methods then applied - have an average recovery factor far below to the
one in such reservoirs which were produced after 1950.
An exact comparison of results of the various countries would have to be based
on equal price - and cost-structures. A realization of this pre-supposition will
not be possible. Also different production policies whether maximising the
recovery factor or accelerating current output do not permit a straight comparison.
Technical progress in drilling and fracturing of oil and gas reservoirs met with
particular interest from coal experts. It was recognised that progress in under
ground coal gasification, a technology which is receiving growing attention in some
Buropean countries, could be facilitated through the use of many of these
traditional oil technique9.
4
The importance of the "drillingtl cost in total capital costs of oil-field
development was stressed. Experts felt that more attention should be paid to
research on reducing unit drilling costs. Certain technical innovations in this
area now in an experimental stage, such as horizontal drilling, might make a very
large contribution to the exploitation of fossil-fuel reserves (i.e. low-permeable
hydrocarbon fields, tertiary recovery and underground coal gasification).
(b) The case of solid fuels
The world reveals extensive coal resources estimated for 10.130 billion tons of
equivalent fuel, but mineable reserves at the present state of art and under
present social and economic conditions are confined to 640 billion tons of
equivalent fuel. It appears, therefore, that reserves currently and potentially
feasible for extraction are rather small in amount and unevenly distributed.
Reasons for the deep divergence between resources and reserves are presented below:
1. In effectively utilized and sufficiently identified coalfields only good
geologic conditions render the possibility of profitable exploitation.
2. Numerous coalfields have not been fully explored by drilling, thus knowing
the estimated resources, no indication could be made of the mineable
reserves.
3. The lack of proved methodology for evaluation of the mineability category
with regard to conditions of the seam occurrence (roof, floor) and potential
mining hazards (rock bursts, water, gas outbursts, rock falls) permitting
to determine the criteria for a profitable exploitation.
4. Many of known deposits with extensive resources and inferred reserves, in
want of the infrastructure necessary for undertaking mining activities,
could not be extracted. This refers to the transport of coal, energy supply,
staff and social problems.
The full supply for energy depends on the possibility to increase coal production.
This depends on ability to solve problems on divergences over resources and
reserves. Generally speaking, coal will be extracted over a certain period by
conventional technologies insofar as a full application of a new generation of
mining technologies is not possible very soon.
Present technologies had been developed, especially those in underground mlnlng,
at a relatively short period, that means after the Second World War, when coal was
losing importance owing to competition from oil.
Consequently, the main factor for a further development of conventional technologies
are geologic conditions of the extracted seams. They play an important role in the
production Size, exploitation costs and on the state of natural hazards, the latter
to combat is expensive.
The second factor is the protection of the environment and minimizing damages
caused by underground and opencast mining as well as the reclamation of land.
Much attention has been paid in recent years to the development of mining tech
nologies for winning of undisturbed and flat seams. This intensive development
is marked by the introduction of full mechanization, the increase in concentration
by using technologies decreasing natural hazards like for example through firedamp
drainage. This development evolved a double impact on the rate of deposit utili
zation through the possibility of working gassy and rockburst-prone seams, but on
the other hand caused a lower extraction rate tendency.
That brings about a divergence of interests for the mining enterprise and the State.
