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Although the number of licences has decreased, exploration continues at an encouraging level. At the end of the period there were in existence seventeen mineral prospecting licences and one petroleum licence. Salt and bauxite conti nue to be mined at Carrickfergus and Ballymena. The most notable development during the period has been the application by Omagh Minerals to operate an open cast gold mine and processing plant near Omagh.
Sustainable development of minerals and petroleum resources can make a vital contribution to economic growth, and the creation of wealth. This report records the Department's contribution to the development of these important resources.
Gerry Loughran
Permanent Secretary
August 1994
Over much of the Province, rocks of Carboniferous age consisting largely of a mixed suite of limestones, sandstones and shales, are confined to the area between the upland ridges formed of Dalradian and Lower Palaeozoic rocks with outliers to the north. In the west, the Carboniferous overlies all the earlier formations and extends to the north, far beyond the subdued Dalradian ridge. The dominant feature in the northeast is the Antrim plateau of basalt lavas of early Tertiary age. This has acted as a protective carapace to the softer Cretaceous, Jurassic and Triassic rocks which now outcrop round the fringes of the plateau. Basins which formed in depressions in the basalt surface resulted in the deposition of clays and lignites of Tertiary age. Over the whole of the region the relics of the Pleistocene glaciation profoundly affect the scenery and human geography. The whole area, save for the highest hills, is blanketed by glacial drifts which obscure the underlying rocks and control the pattern of settlement and agriculture. Ice from Scotland played a major part in the glaciation of the eastern part of the country, but in the west, Irish ice from Donegal and possibly from centres in the Sperrins, was dominant. The advance and decay of these ice-sheets have left their mark in morainic deposits, drumlins the relics of glacial lakes, and the moulding of the landscape.
Following the gas discoveries at Dowra-1 and Macnean-1 in County Cavan, three wells were drilled in County Fermanagh during 1965-66. Gas shows were recorded in Big Dog-1 and Owengarr-1 but Glenoo-1, on Slieve Beagh, was dry. Interest in the area lapsed when testing of the wells produced, at best, non-commercial gas flow rates.
The main factor limiting the producibility of gas is the poor quality of the reservoir sandstones. The sandstones have low porosities and permeabilities which means that relatively low concentrations of hydrocarbons are trapped in often isolated pore spaces from which they are difficult to extract.
In 1980 a group led by Marinex obtained a licence in the Republic of Ireland which included the previous Dowra-1 and Macnean-1 discoveries. Marinex re-entered Dowra-1 and tried to improve the permeability and gas production by acidising and fracturing the reservoir interval. Flow-rates increased almost tenfold from c 30000 cubic feet of gas per day (CFGD) to 250,000 SGFGD. Thus encouraged, the group acquired a licence for large areas of County Fermanagh, Tyrone and West Armagh in 1981.
This second phase of exploration involved a more integrated approach combining geology, geochemistry and geophysics. Detailed geological mapping of the Fermanagh Highlands was undertaken as were studies of the richness and maturity of potential hydrocarbon source rocks. A seismic reflection survey was run over the contiguous licences in Northern Ireland and the Republic of Ireland. This resulted in the identification of a number of prospective structures.
As a result of this work, four wells were drilled during 1984 and 1985, two in the Republic of Ireland followed by two in County Fermanagh. The first three wells, Macnean-2, Drumkeeran- l and Slisgarrow- l all had gas shows but did not flow gas to the suriace when they were tested. The final well, Kilcoo Cross- l, had a target within the Old Red Sandstone beneath the Carboniferous. The Old Red Sandstone reservoir did not match up to prognosis although gas shows were encountered within the shallow Carboniferous sandstones. The consortium did not renew their interest in the licence which expired in 1987.
The Northwest Carboniferous basin can be summarised as an area with known gas (and to a lesser extent, oil) generation and entrapment but poor reservoir quality. Future commercial hydrocarbon production probably depends on the identification of areas of better quality reservoir rocks, perhaps enhanced by fracture porosity. Advances in techniques for extracting hydrocarbons from tight reservoir smay also increase the viability of the known accumulations. Perhaps the best reservoir potential lies below the normal exploration targets in the Basal Clastics, which produced good water flow rates in the Glenoo borehole.
Interest in the area has resumed recently with research into the distribution and quality of both reservoir and source rocks.
Marathon acquired the first licence in this area in 1968, covering part of southeast Antrim onshore and the adjacent offshore. One well, Newmill No l, was drilled under a farm agreement with Shell in 1971 on the south-west ern shore of Larne Lough. This well was located on a surface anticline and proved a thick Permo-Triassic sequence including potential reservoirs in the Triassic Sherwood Sandstone Group and Lower Permian Sandstones, but gave no significant hydrocarbon indications. The licence expired in 1975 and hydrocarbon exploration in the northeast of the Province ceased for a number of years.
Energy Sources (Nl) Ltd were awarded a licence covering 357 sq km around Ballycastle and Rathlin Island in l 980 and in l 982 a group led by Anvil Exploration Ltd obtained a licence over an adjacent area of l ,412 sq km in north Antrim and County Londonderry. Offshore seismic surveys were shot under both licences to try and define the deep structure of coastal geological features. Several exploration leads but no definite prospective structures were identified from these surveys.
In l98l the then Department of Commerce (now DED), acting on advice from GSNI, instigated a programme of research which was particularly influential in stimulating subsequent hydrocarbon exploration activity in the northeast. The thick basalt cover had previously proved a deterrent to onshore exploration so an experimental seismic survey was shot in southeast Antrim and west of Lough Neagh in December l98l, partly over basalt outcrop. The results proved that, with sufficient vibroseis source energy and modern processing techniques, useful reflections could be obtained from the sedimentary rocks Iying beneath the basalts. Studies of source rock potential commissioned by GSNI at this time also proved the existence of gas-prone source rocks within the Carboniferous rocks of Northern Ireland. DED also commissioned a follow-up vibroseis survey over the basalts west of Lough Neagh in l 983. Reflector quality in the prebasalt section was good enough to allow a time structure map to the Permian Magnesian Limestone to be made from this reconnaissance grid. In 1984 a gravity survey was run over Lough Neagh, using a lake-bottom gravimeter, and the results indicated the presence of a number of sedimentary sub-basins beneath the lough.
Anvil Exploration shot a vibroseis survey over the northern part of their licence area in 1982 but quality was variable and they undertook a detailed gravity survey in 1983 to try to develop some structural leads. These leads were used to plan their 1984 vibroseis survey, the acquisition and processing of which leant heavily on the experience gained from the earlier DED seismic surveys. Anvil subsequently identified one drillable structure but, following a reappraisal of the data by both GSNI and the operator, they decided that it was too shallow to be prospective. The Anvil licence expired without drilling and the Energy Sources licence was revoked when the licensee failed to complete the scheduled work programme. In 1985, DED offered three areas for licensing, one in the Rathlin Trough and the other two in East Antrim. As a result, Fynegold Petroleum plc was granted a licence to explore 340 sq km of County Antrim, to the north of Larne. In 1987 DED commissioned Robertson Research International Ltd to carry out a review of the hydrocarbon potential of northeast Ireland as the prelude to a departmental initiative to heighten interest in petroleum exploration in the area. GSNI contributed to this review particularly by instigating an interpretation of the Bouguer gravity anomaly data by BGS Regional Geophysics Research Group. This study was important in helping to constrain the extent and depth to base of the concealed sedimentary basins. Two further licences were issued as a result of this initiative, to Northwest Exploration plc to the north and south of Lough Neagh, and to Mustang Oil Ltd in East Antrim, north of Belfast Lough. A group of companies led by Lough Neagh Exploration (formerly known as Ulster Natural Resources Ltd) now holds a licence north of Lough Neagh over some of the acreage originally licensed to Northwest Exploration plc.
Fynegold drilled an exploration well at Ballytober 6 km northwest of Larne in November-December 1990 and the PL6/86 licence expired in November 1991, without renewal. Ulster Natural Resources commissioned a Vibroseis seismic reflection survey over the licence area north of Lough Neagh and, as a result, several US exploration companies farmed in to the licence. One of these companies, Nuevo Energy Company, acted as operator for an exploration well drilled at Annaghmore,2 km south of Toome, in February-March 1993. This licence has entered its first renewal period and is still current. The licence in east Antrim held by Mustang Oil Ltd expired in 1993 without reaching the drilling stage. The exploration results from these three recent licences are still confidential. There have been several expressions of interest in exploration in the Lough Neagh and Larne basins over thelast 18 months and the Department is currently appraising exploration licence applications.
The concealed sedimentary basins in the northeast of the Province remain relatively little explored and retain significant exploration potential. Carboniferous coals and organic-rich shales outcrop in East Tyrone and, buried to greater depths in the main sedimentary basins, would be expected to have generated hydrocarbons. The PermoTriassic sandstones commonly hav e good to excellent reservoir properties and the mudstones and salt sections should form effe ctive seals. Tilted fault blocks within the basins are also likely to form structures capable of trapping hydrocarbons. One of the main risks in exploration is in the distribution of potential Carboniferous source rocks beneath the reservoir sequence. The deepest boreholes in the Lough Neagh and Larne basins, Ballymacilroy and Larne No 2, bottomed in Permo-Triassic rocks without proving the presence or absence of Carboniferous strata below. Lack of knowledge about these potential source rocks also prevents accurate modelling of the relative timing of hydrocarbon generation, trap formation and the migration of the relative timing of hydrocarbons from source to reservoir.
No new licences were issued during the three year period ended 31 March 1994.
Petroleum Licensing Position on 31 March 1994
The petroleum licensing position at 31 March 1994is set out below. The location of the licence is shown on the map.
Preliminary discussions with the Department and the Geological Survey of Northern Ireland (GSNI) It is useful for a company thinking of applying for a licence to have preliminary discussions with both the Department and GSNI. GSNI is the repository for all geological information in Northern Ireland and staffthere can advise on the prospectivity of any particular area. A considerable amount of data obtained by companies under licence and by DED through its own exploration programme is available tor inspection or for purchase. (Further information about GSNI is provided in Section 4.)
Licences can be issued for areas up to 350 sq km; licensees are required to carry out agreed work programmes and to report on these to the Department. This information is kept confidential, if a company so requires, for up to ten years but after that it becomes publicly available.
Licences give licensees the right to explore over the whole licensed are a. The regulations concerning entry on to land are set out in section 47 of the Mineral Development Act (Northern Ireland) 1969 which also applies to petroleum licences. The Department also expects licensees to seek the agreement of landowners before entering their property. Compensation is payable by licensees for any damage that may be caused during exploration.
The application must be accompanied by two original 1:50,000 Ordnance Survey of Northern Ireland outline maps. The application area should be clearly delineated and the boundary should normally follow grid lines. The relevant fee (currently £1,000) and audited accounts for the three most recent years should also be included.
The Department expects the applicant to provide a rationale for the proposed programme, showing an understanding of the geological information already available, and to submit a phased and costed work programme.
Before issuing a licence the Department must be satisfied that the applicant has the technical and financial resources to carry out the proposed work programme. The Department therefore takes advice from both GSNI and consultants on the technical merits of the application and from an accountant on the company's ability to finance the work. Although not required to do so under the provisions of the Petroleum Production Act, the Department, following the procedure laid down in the Mineral Development Act, consults other departments and public bodies about its intention to grant a licence. All representations are considered by the Department and, if appropriate, passed to the company together with the draft licence. This 'letter of offer' may appear to contain a large number of conditions as some consultees anticipate possible developments at a later stage. At the exploration stage, however, it is normally sufficient for the company to keep the contacts, who are listed, informed of its plans and progress.
When the terms of the draft licence have been agreed and the conditions in the 'letter of offer' are accepted, the engrossments of the licence are prepared and then executed by both the company and the Department.
The Geological Survey has powers under the Minerals (Miscellaneous Provisions) Act l 959 of access to land to carry out its work and the Act also requires that the Survey be informed of, and allowed to inspect, every borehole more than l5m in depth.
The results of the Survey's investigative programmes by m apping and other exploration methods are presented in colour printed I :50,000 scale (formerly l inch to l mile) maps, memoirs and various reports.
The map illustrates progress to date in resurveying and publishing both maps and memoirs. Of the sheets which have been resurveyed but for which maps are not yet published Draperstown (26) is in press, and Londonderry ( l l ), Omagh (33) and Lisnaskea (57) are being compiled.
Following the appraisal of the east Tyrone and north Antrim coalfields some 17 boreholes were drilled in search of coal and evaporite deposits in Tyrone and l 0 in search of coal in Antrim. While workable coal was identified in Antrim no workable reserves were found in Tyrone and interest turned towards trying to locate coal deposits beneath postCarboniferous strata in the north east of the Province. In particular, deep boreholes were drilled at Newtownards (Ballyalton), Templepatrick and Langford Lodge - all without commercial success. However, knowledge from these boreholes increased the geological data base and resulted in the evaluation of other possibilities.
Following these boreholes, gravity and aeromagnetic surveys of the Province were carried out. These geophysical surveys confirmed the existence of major sedimentary basins near Larne, Ballycastle, Magilligan, Portglenone, Lou gh Neagh and Newtownards; all of which have subsequently been proved by drilling.
Consequently, the Survey planned and commissioned a vibroseis survey in 1981 to investigate whether usable data could be obtained from beneath the basalts. The results were promising and subsequent work in 1983 by the Survey and by exploration companies has confirmed the usefulness of this technique. A more detailed account of this work is included in Section 3. l Petroleum Exploration in Northern Ireland 1964- 1994.
Seismic data coverage of Northem Ireland remains sparse, however, and the analysis of potential field data - gravity and magnetic anomalies - provide another method of modelling the deep geological structure. In 1987 DED commissioned a report on the interpretation of gravity anomaly data of Northern Ireland by the Regional Geophysics Group of the British Geological Survey. A series of 2.5 dimensionally modelled profiles across Northern Ireland, and the application of image analysis techniques to processed gravity and magnetic data, allowed new insight into the major structures defining the sedimentary basins and the possible thickness of sedimentary fill. More recently GSNI initiated a study of the Permo-Triassic potential reservoir and caprock sequences, currently being carried out by BGS Biostratigraphy and Sedimentology Group. This study uses palynology and geophysical log characters to establish a detailed stratigraphic framework for the thick, mainly 'red-bed', Permo-Triassic sequences proved in deep boreholes in the concealed sedimentary basins of northeast Ireland. The results of this study should help to elucidate Permo-Triassic basin development and subsequent differential fault movement. This data is important for modelling the burial history of potential source rocks and the relative timing of trap formation, and the generation and migration of hydrocarbons.
GSNI with experienced geologists and as the custodian of extensive collections of records is in a unique position to provide geological information about Northern Ireland. The Borehole Database is being converted into digital format and completion to index level is expected shortly. A Mineral Resource Information Project is being undertaken, with the assistance of the Minerals Group of the British Geological Survey and a Mineral Occurrences Database and a Mineral Licences Database are currently being developed. The resources are available for consultancy purposes, research studies and general advice, provided that charges are met for specific services. Details can be obtained from the Survey of fice. All non- commercial company data are available for consultation.
Minerals and Petroleum Unit
Department of Economic Development
Lough Neagh Exploration Ltd
Carboniferous basins, Fermanagh and Tyrone
The first exploration licence, issued to Marathon, covered 3600 sq km, mainly over the Carboniferous outcrop of Counties Fermanagh and Tyrone. This outcrop, and the underlying sediments, form part of the major Irish Northwest Carboniferous basin which straddles the border and occupies much of Counties Fermanagh, Tyrone, Cavan, south Donegal, Leitrim, Monaghan and Sligo. Drilling has shown that there is a thick succession of up to 2500 metres of Lower Carboniferous rocks in this basin. These are mainly marine sediments and include organic-rich shales and deltaic sandstones that are potential hydrocarbon source and reservoir rocks, respectively.Concealed sedimentary basins, northeast Ireland
In the northeast of the Province, largely concealed by the Tertiary basalts, there are a number of fault-controlled sedimentary basins which have been another focus for hydrocarbon exploration. The existence of these deep sedimentary basins was predicted by geologists in the middle of the last century and was proved by a series of deep boreholes commissioned by the Northern Ireland Government in 1960-61 and 1978-79. The boreholes established the existence of good quality sandstone reservoirs with effective overlying mudstone and salt seals within the thi ck Permo-Triassic fill but although mature Carboniferous source rocks are postulated to be present in at least some of the basins their occurrence has so far not been established.Petroleum Licensing
1 April 1991-31 March 1994
Map showing Petroleum Licensing position on 31 March 1994
Licences issued
Period 1 April 1991-31 March 1994Petroleum Licences - Guidance for Applicants
The Petroleum (Production) Act (Northern Ireland) 1964 vested petroleum in the Department of Economic Development and enabled the Department to grant licences to commercial companies to search for, bore for and get petroleum. The Department's licensing system is based on the 1964 Act and on the subsequent subordinate legislation, which is listed at the end of this section. The main points are however, summarised below. Licences
The Department has at various times held licensing rounds and invited applications to be lodged by a certain date. However if no licensing rounds are planned in the immediate future, the Department will consider applications on an individual basis. Petroleum licences are granted for an initial period of five years but can be renewed in accordance with the provisions of the regulations for a further term of five years. If it is demonstrated to the satisfaction of DED, that commercial qualities of oil or gas are to be found in the licensed area, a final 30 year term may be granted (subject to at least half of the original licence area being surrendered).Applications for Licences
The method of application is set out in Schedule 1 of the 1987 Regulations.Processing the Applications
Applications on average take a minimum of six months to process. Planning Permission
Planning permission is not required for the early stages of exploration though the Planning Headquarters of the Department of the Environment (DOE) should be kept informed about a company's exploration programme. However planning permission is required at the drilling stage. DOE has a statutory duty to consult district councils for all developments including drilling within their areas. Royalties and Compensation to the former owners of Petroleum Rights
Under the 1964 Act and the 1965 Regulations on Royalties a 7.5% royalty is payable on all petroleum 'won and saved'. This would be passed to the former owners of the petroleum rights by way of compensation. Relevant Legislation
Petroleum (Production) Act (Northern Ireland) 1964 Petroleum Production Royalties - SR 1965 No 48 Petroleum Production Regulations (Northern Ireland) 1987 -SR 1987 No 196
Background
From 1922-47 the only source of geological advice available to the Government of Northern Ireland was the small staff of the Department of Geology at the Queen's University of Belfast, supplemented during the war years by special investigations carried out by the Geological Survey of Great Britain. Immediately after the war the need for a detailed scientific assessment of the mineral potential of parts of Northern Ireland was recognised and the Geological Survey of Northern Ireland (GSNI) was established. The scientific staff of GSNI were and are drawn from the Geological Survey of Great Britain, now the British Geological Survey (BGS), under an agency arrangement which also enables GSNI to draw on expertise in other parts of BGS. Repository of geological information
In 1964 the Petroleum (Production) Act (Northern Ireland) became law enabling the Department (then the Ministry) to grant licences for searching and boring for petroleum. Subsequently, in 1969 the Mineral Development Act (Northern Ireland) provided the Department with similar powers in relation to a range of other minerals and specifically made provision for the reporting of exploration results, including geochemical and geophysical data, to the GSNI.Geological Mapping
During the discussions on the establishment of GSNI in 1947, it was agreed that the assessment and promotion of the mineral resources of Northern Ireland would be linked to systematic resurvey of the area beginning with an evaluation of the Carboniferous coalfields in east Tyrone and north Antrim.Map Availability
Mineral Exploration
From its inception in 1947 the Geological Survey has been actively involved in mineral exploration not only through its mapping programme but also by drilling and geochemical and geophysical surveys.Hydrocarbon Exploration
While legislation to facilitate hydrocarbon exploration had been in place since 1964, comparatively little work had been undertaken by 1980, due mainly to the perceived difficulty of obtaining reasonable quality seismic data from beneath the basalt cover in the northeast of the Province where a thick Mesozoic prospective sequence was known to occur.Geological Survey of Northern Ireland
Lignite Exploration
In 1983 the Survey also began an exploratory drilling programme to investigate the possible occurrence of lignite in the Lough Neagh Group outcrop which resulted in the discovery of two new lignite prospects, namely the Ballymoney and Coagh deposits. Prospecting licences were subsequently granted in respect of both of these to exploration groups. More information about this work is contained in Section 2.1 Mineral Exploration and Development in Northern Ireland 1969- 1994. Section 4.7 Assistance from GSNI
Netherleigh
Massey Avenue
BELFAST BT4 2JP
Tel: (0232) 529900 - Switchboard
(0232) 529381 - Direct
Fax: (0232)529550
Geological Survey of Northern Ireland
20 College Gardens
BELFAST
BT9 6BS
Tel: (0232) 666595
Fax: (0232)662835
Planning Headquarters
Department of the Environment for Northern Ireland
Clarence Court
10-18 Adelaide Street
BELFAST
Tel: (0232) 540540
Fax: (0232)540024
Ordnance Survey of Northern Ireland
Department of the Environment for Northern Ireland
Colby House
Stranmillis Court
BELFAST
BT9 5RJ
Tel: (0232) 661244
Fax: (0232) 683211
Crown Mineral Agent
Wardell Armstrong
Lancaster Building
High Street
NEWCASTLE-UNDER-LYME
Staffordshire
ST5 IPQ
Tel: (07821) 612626
Fax: (07821) 662882
Companies' Registry
IDB House
64 Chichester Street
BELFAST
BTI 4JX
Tel: (0232) 233233
Fax: (0232) 326403
33 Hamilton Road
BANGOR
Co Down
BT20 4LF
Nuevo Energy (Nl) Company
7 Creagh Road
TOOMEBRIDGE
Co Antrim
BT41 3SP
Additional Irish Stuff