TURKEY - Turkey's Oil & Gas Fields - TPAO.

TPAO holds about 180 concessions in Turkey. Out of these, 43 are production areas, including joint ventures with BP. In the exploration areas, TPAO is trying harder to find natural gas near the oilfields. The gas is needed for reinjection into old fields where reservoir pressure has declined considerably in recent years.

The Raman group of connected fields in Si'irt remain the biggest oil producers for TPAO. The first one, Raman, was found in 1945. It produces 18.8 deg. API oil with 4.1% sulphur from an Upper Cretaceous formation at a depth of 4,500 feet. Raman West (Bati Raman), found in 1961, is the largest structure in Turkey producing 13.3 deg. API oil with 5.7% sulphur from an Upper Cretaceous reservoir at a depth of 4,200 feet.

Germik, found in 1958, was TPAO's first discovery and the third oil find in Turkey. The field is north-west of Garzan, not far from Raman. It is on trend with Garzan. But it is small, producing only 80 b/d, compared with 120 b/d in 1998, 150 b/d in the first quarter of 1996 and 180 b/d in 1988. The oil is 19 deg. API with 2.8% sulphur.

Ikiztepe, discovered in 1976 by TPAO, is one of the Si'irt fields extending into Syria. Its oil being 11.3 deg. API with 4% sulphur. Ikiztepe's extension on the Syrian side is known as Sa'id field, with both sides producing from an Upper Cretaceous reservoir at a depth of 4,900 feet. Ikiztepe was closed in 1989 because of a rapid fall in reservoir pressure. By end-1988, the field had produced 88,051 barrels. Later Japan National Oil Corp. (JNOC) provided TPAO with assistance for an EOR system at the field.

TPAO is a non-operating partner of the other oil producers in Turkey (see OMT).

From late 2000 TPAO's exploration efforts in Turkey have not resulted in major oil discoveries. In the autumn of 2000 it found oil in the Kozluk Selmo block in the Batman district. The field went on stream in 2001 at the initial rate of 2,500 b/d. But this declined from late 2001. Since late 2001, TPAO's production has been exceeding its reserves discoveries. In 1996, TPAO added 18 new wells to its oil production system and their output during that year totalled over 1.33m barrels. They included the Bozova structure in the Adiyaman axis of fields, which the company discovered earlier in that year. In 1997, the company added 12 new wells which during that year produced almost 900,000 barrels.

During those two years, over 20 old wells were abandoned. Now, the number of active wells in TPAO's production system is more than 800 compared to 670 wells by end-1995. In 1996 and 1997, TPAO drilled more than 45 exploration and appraisal wells with a cumulative depth of more than 55,000 metres. The company made five oil and gas discoveries during those two years.

Mobil in 1964 found another field in Si'irt, containing 34.4 deg. API oil. But these fields remained small. Re-exploration resulted in small discoveries. Mobil sold its interests in its producing fields to TPAO in 1994, when their total output was about 3,000 b/d. Mobil continued to operate in the country as an explorer and as a downstream investor.

Shell came in during the late 1950s and took blocks in the Diyarbakir and Gaziantep provinces. It started exploration in 1960. In 1961 it found two connected fields at Kayakoy, in Diyarbakir, containing 34.7-38.2 deg. API oil. At the same time, TPAO found a third connected field, Kayakoy South. This contained 30.4 deg. API oil, but the structure was small.

Shell found many other fields in that region, and all were small. In Gaziantep, Shell's first find was Piyanko, containing 35.5 deg. API oil. By 1994, when it offered to sell its interests, it had 27 developed fields together producing 13,400 b/d.

(See summarised profiles of main Turkish oil and gas fields in OMT of this week).

All prospective blocks in Turkey have been licenced. TPAO acts as an operator in its own concession areas and as a partner of foreign companies elsewhere in the country.

Improved E&P terms in March 1983 encouraged a number of firms to explore in Turkey. A major oil discovery in 1989 lured more companies to Turkey. But the pace of discoveries was slow in the subsequent years and many have since left the country. Oil in place, defined as "ultimately recoverable", may exceed 2.3 bn barrels mostly in Raman West, Turkey's largest field. But the oil there is 13.3 deg. API with 5.7% sulphur and cannot be recovered because of a permeability barrier. Only a small part is recoverable under a current EOR system involving CO2 flooding.

Firms which came to Turkey included Roy M. Huffington of the US, which acquired 13 licences at the north-western end of the Taurus-Zagros belt and other acreage then said to be rich in gas. Offshore and onshore exploration in Iskenderun Bay was undertaken by TPAO and Salen Energy of Sweden, but the outcome was negative. US, Canadian and Norwegian firms led by Seahawk took the Saros Bay acreage. Barrick Petroleum of Canada joined TPAO in a Black Sea block as well as in the onshore Sinop and Samsun Basins. Lennox Oil of Scotland took the Salt Lake Basin in central Turkey. In March 2004 Omax Resources of Canada acquired a one third interest in the Adana oil and gas exploration zone in southern Turkey. Omax acquired the stake in return for a 16.7% interest in another Turkish exploration property, the Iskenderun concessions. Following the transaction, Omax got 33.3% in both the Iskenderun and Adana exploration blocks for a net holding of about 127,000 hectares in Turkey.

The Thrace-Gallipoli Gas Basin, a promising area offshore in the Marmara Sea, has been taken by TPAO for both exploration and development with US assistance. A major gas discovery made there in 1988, Marmara Kuzey, was put on stream in 1997. This was Turkey's first discovery of non-associated gas. The field's recoverable reserves have been estimated at between 105-140 BCF following two successful appraisal wells drilled in 1995. The gas is linked by pipeline to the Turkish domestic market.

In March 2002 Amity Oil, a small Australian company based in Perth, announced a gas find in its second appraisal well in the Thrace Basin. Gocerler-3, drilled in Block 3589 to a depth of 1,405 metres, had what it called "excellent gas shows" in three reservoirs. Its first gas discovery through Goverler-1 well in October 2000 tested 12.4 MCF/day of gas and some condensate from a Tertiary Danishmen formation at a depth of 1,656 metres.

Amity has since made several gas discoveries. It began gas production in January 2002 at the rate of 5 MCF/day. This was raised subsequently to 12 MCF/day. Now it is producing about 50 MCF/d, with Gocerler's output of 20 MCF/d expected to last for five more years. But at times Amity's output rose to 70 MCF/d. The gas is sold in the Thrace region. Amity and TPAO hold 50% in Blocks 3589 and 3648 were several fields have been found and developed.

Total gas production in Turkey now averages between 460-480 MCM/year, up from 310-330 MCM/y in the first quarter of 2004 and 181.5 MCM/y in 1995. Until the early 1990s, production was negligible and mostly associated with oil output onshore. Nearly all the associated gas extracted now is reinjected into oilfields as part of EOR systems. The Energy Ministry's Natural Resources Department owns the associated gas lying in reservoirs operated by companies other than TPAO. These firms' use of associated gas for reinjection into their fields must be the subject of prior agreements with the Department and TPAO.

Most of the fields producing non-associated gas and operated by TPAO lie in the Thrace and Marmara regions. They include Marmara Kuzey, or North Marmara, which has been the largest of the gas fields in Turkey. Found in 1988 by TPAO, it is an offshore structure in the gas-prone Thrace-Gallipoli Basin in the Sea of Marmara. Developed by TPAO, the field produces 50 MCF/day. It went on stream in May 1997. Momentum Engineering of the US has built and installed an unmanned production platform, under a contract awarded by TPAO in January 1996. The US company has also installed a pipeline network to link the marine and land sections. A separator plant has been built onshore by Monument under the same contract. This is at the nearest point to the field and is processing the gas. From there, the clean gas is supplied to the market in and around the Marmara region and some of the suburbs of Istanbul.

The discovery well, Marmara Kuzey-I, in 1988 tested 27.5 MCF/d from an Upper Eocene limestone called Sogucak. The gas then was estimated at 70-80 BCM. The second well, drilled in 1988-89 to check a northern extension, was stopped dry. Two other wells, M. Kuzey-3 and M. Kuzey-4, drilled in 1995 yielded gas. The field now is producing from M. Kuzey 1, 3 and 4.

Marmara Kuzey lies at a depth of 1,120 metres, below 40 metres of water, and is about 2.5 km from the shore. It is 6 km south-west of Silivri town, near the small gas field of Silivri which is now producing, and 120 km west of Istanbul. The total depth reached by TPAO is 1,262 metres, to the point reached in the M. Kuzey-2 effort. TPAO said in 1995 that the third and fourth wells confirmed the homogeneity of porosity within the Sogucak reservoir. The company's executives said they were confident that TPAO would extract up to 140 BCM from the field, i.e., all the gas estimated to be recoverable at Marmara Kuzey.

TPAO's plan is that, after all the 140 BCM gas reserves at the field have been produced, Marmara Kuzey will be used as a natural underground storage facility. This will be similar to the storage facility at the depleted Degirmenkoy gas field in Thrace. Gas storage facilities are also being built in the salt lakes near Ankara.

A search for other such fields on the Sea of Marmara was launched in 1996. TPAO in 1996 found two non-associated gas fields in that region: Silivri-2 and Yulafli-1. These were developed and put on stream but their production is small.

TPAO's other producing fields include Hamitabat, whose output averages 100 MCM/y; Degirmenkoy, producing more than 70 MCM/y; Karacali, producing almost 20 MCM/y; Karacaoglan, producing 1 MCM/y; Umurca, producing almost 100,000 CM/year; and two Silivri wells, producing more than 50,000 CM/year. The quantities produced from these and many smaller fields are being purchased from TPAO by users in Thrace.

TPAO produces about 18 MCM/y of non-associated gas from the onshore Camurlu field in the Batman region of southern Anatolia. A part of this gas is purchased by the Mardin Cement Factory and the Nusaybin Regional Boarding School, with 7 MCM/y being utilised in surface facilities of some TPAO oilfields.