Technologies related to oil activity

The geological studies carried out in the past by US companies as well as more recent studies show the existence of geological structures in the EEZ that are favourable for oil prospecting. Crude oil extraction began to show signs of recovery in 1992, two years before the economic recovery that started in 1994.

Although, initially, the extracted volume of crude oil was insignificant, a positive trend in the production was observed. The annual average was twice

the volume registered in 1989 and approximately three times higher than that registered in 1991.

Oil exploration in Cuba is based on geological and geophysical methods including field surveys or field measurements, sampling, and seismic, electrical, gravimetric and magnetic surveys. Oil–gas and bacteriological analyses are also undertaken.

The increase in oil discoveries in deep waters and the fact that an increasing number of important companies are devoted to oil extraction aroused Cuba’s interest in deepwater oil extraction technologies. Conse-quently, joint ventures have been established, especially with Brazil, Canada and Spain, for the exploration and exploitation of deposits in the EEZ. An important energy development programme was put into effect in February 2000, with the official opening of the EEZ in the Gulf of Mexico to foreign investment. This area is considered by experts to be the world’s most potentially productive offshore oil zone and probably one of the last areas of the world not yet explored for oil.

By the end of 2000, important progress had been made in drilling the first exploratory oil well in the sea platform to the north of Ciego de Ávila province.

The 75 km oil pipeline that stretches from the Varadero oil deposit to the supertanker base in the city of Matanzas was completed that same year. The pipeline transports crude oil, replacing the coastal traffic; this provides an economic benefit of more than US $10/t of oil transported.

Exploratory wells have already been drilled in the EEZ, as have assessment wells, used to establish the oil deposit limits. Some of these assessment wells have become production wells. Initially, when it was decided to put the wells into production, they were neither hermetically sealed nor interconnected. Under certain conditions, the oil naturally reached the surface, pushed by the pressure in the oil-bearing strata. However, in other instances it was necessary to install rocking beam pumps or to use other methods to retrieve the oil. When the number of production wells increased, it was decided to connect them wherever possible in order to raise the yield of the wells and to use the associated gas.

Most of the wells in the country are vertical but in some directional drilling technology has been used. Recent developments have made it possible to deviate up to 90^o from the vertical position using this kind of technology.

Horizontal and multipipe drilling has allowed a four- to fivefold reduction in drilling terms and a five- to sixfold increase in production compared with conventional wells. Improvements in the Rotaflex pumping system have allowed well productivity to increase two- to threefold.

4.2.6.1. Oil refining

Most of the domestic crude oil is very heavy and has a high sulphur content; therefore, it is necessary to use additives (cutter stock, diesel, etc.) to make its extraction and transport easier. At the Matanzas supertanker base, it then undergoes a thermochemical process of dehydration and desalinization at atmospheric pressure. This process makes it feasible to obtain a better quality, higher value product that is easier to transport and which requires lower maintenance expenditures for the clients. This improved crude oil is used by thermal power plants and by the nickel and cement industries.

Before 1959, there were three oil refineries in the country, all of which belonged to North American companies. When these industries were nation-alized, the supply of spare parts was immediately stopped. Through the years, the efforts and technical expertise of the Cuban staff has enabled damaged equipment to be repaired with spare parts designed domestically. These industries have been able to continue functioning as the result of the commitment and technical solutions provided by Cuban staff. Today, 86% of all the refinery equipment is produced in Cuba.

Currently, there are three refineries operating in the country, with a refining capacity of 2.9 million t of oil. The upgrading of a fourth refinery at Cienfuegos is being negotiated with foreign firms. When it is finished, the refining capacity of the country will increase to 5.9 million t. This refinery was built in the 1980s with technology from the former Soviet Union and was in operation until 1992 when it was shut down owing to the low efficiency of the plant and to the incomplete refinery process.

The increase in the domestic production of crude oil has enabled Cuba to increase refinery production and thus obtain finished products that are less expensive than imports, e.g. gasoline, diesel and LPG. Consequently, in the last several years, hydrocarbon import costs have been reduced and in 2000 savings of about 90 million pesos were realized.

Initially, there was limited production of these products in Cuban refineries, which processed 1 million t of crude oil in 1999. However, by 2000 that figure had increased to 2.1 million t. This increased production also allowed for an increase in the production of domestic fuels — LPG and kerosene — and thus improved supply to the population, with the support of the country’s domestic fuel substitution programme [4.12].

The Ñico López refinery in Havana province, which is the only refinery capable of producing every product, imports a light crude oil with a low sulphur content that, when blended with the Cuban crude oil, enables the best yields to be obtained. In the case of the Hermanos Díaz refinery in Santiago de Cuba province, a more economic crude oil with a lower yield than the light crude oil

is processed. This refinery produces fuel oil which, in turn, is used by the Ñico López refinery.

These mixtures of selected imported and domestic crude oils have made possible a 20% increase in the proportion of national crude oil in the refining mixture without affecting the production of products or their quality.

The country’s facilities for the extraction, storage and transport of oil and gas are shown in Fig. 4.2.

4.2.6.2. Use of associated gas

Up to 1998, associated gas from the main oil deposits (as in Varadero–

Cárdenas) was flared without deriving any energy benefits, thus polluting the air and affecting the important tourist area of Varadero. To make use of associated gas and to counteract the environmental impact of flaring the gas, the Energas joint venture company was established with the Canadian company Sherritt International to produce electricity. Sherritt holds 33.3% of the shares, UNE holds another 33.3% and the remaining 33.3% of the shares are owned by CUPET. Sherritt contributes technology and financing, CUPET provides the raw material and UNE, the market. Energas, in addition to producing electricity in gas turbines and combined cycles (highly efficient technologies), also produces LPG, a condensate similar to naphtha (about 40–45 m³/d) and high purity sulphur for industry (45–50 t/d).

The associated gas is now used in gas turbines for electricity generation in Jaruco. The processing plant used to clean this gas was modernized and enlarged so that the gas could be used as a raw material in the production of a

FIG. 4.2. Oil facilities in Cuba. Source: Ref. [4.13].

higher quality manufactured gas at the Melones factory, in Luyanó. A new combined cycle plant is foreseen for these locations.

From Jaruco, the associated gas is supplied through a gas pipeline to the other distributor of city gas in the provincial capital, the Marianao factory. At present, most of the city gas in the capital is obtained from associated gas, which represents an annual saving of more than 8–9 million pesos, as it substitutes for naphtha. Now naphtha can be exported to finance other CUPET operations.

This situation has allowed greater availability and wider distribution of city gas, especially in Havana. The distribution system has been improved and enlarged, and gas meters are now widely used. The meters have led to a reduction in city gas use per household.

In addition, joint ventures have been established with a Dutch and a French company in order to build two new plants for LPG production, one of them in Havana and the other in Santiago de Cuba. The fuel substitution process has also begun in other provincial capitals.

4.2.6.3. Fuel transport

Existing oil and gas pipelines, as well as those in their final stage of construction, are shown in Fig. 4.3. These pipelines increase the safety of operation and reduce the losses and costs of transport activities. The transport system connects the oil deposits with the LPG and city gas producing plants,

FIG. 4.3. Cuban energy network. Source: Ref. [4.14].

the supertanker base, the Ñico López refinery and the José Martí International Airport.

Before the construction of the oil pipeline, oil was transported from the port of Cárdenas to the supertanker base by ship, which resulted in an additional cost of 7–10 pesos/t, in addition to the high environmental risks due to fuel spillage in this important tourist area. Currently, the transport of crude oil through the pipeline costs slightly more than 1 peso/t. In addition, the oil pipeline has allowed a continuous supply of crude oil, whereas at times in the past high winds hindered shipping operations. Moreover, the oil pipeline enables the simultaneous loading and unloading of ships at the supertanker base.

To ease the flow of heavy crude oil through the oil pipeline and achieve quality in accordance with export requirements (1400 centistokes), a technique consisting of adding a solvent to the oil was introduced. Therefore, as the crude oil transported from Varadero to Matanzas is lighter, operations and mixtures become easier, the costs for the supertankers and the producing company are lower, and maintenance and electricity costs for pumping are reduced. The oil pipeline, with an original capacity of 1.5 million t, guarantees the transport of current oil production but could also transport up to 2.5 million t.

The pipeline from Puerto Escondido to the Matanzas supertanker base transports about 1000 t/d of fuel; in the past, this fuel was transported by truck using the Via Blanca road. The pipeline from Jaruco to the Ñico López refinery also obviates the need for road transport.

The turboduct enables aviation fuel to be transported directly from the Ñico López refinery to José Martí International Airport, thus avoiding its transport by train.

The gas pipeline from Puerto Escondido to Jaruco transports gas to the associated gas treatment plant. The oil wells in the area of Cárdenas–Varadero have also been hermetically sealed and the supply of gas is sent to the sulphur production plant, to gas turbines and to the Energas combined cycle plant for electricity generation.

Fuel for the thermal power plants of Nuevitas, Felton, Renté and Maximo Gómez is transported by ship.

The LPG is distributed to end users mainly in 19 kg cylinders; the distri-bution system, which relies on a fleet of trucks, has been enlarged. On average, between 20 000 and 27 000 gas cylinders are filled daily to maintain service.

4.3. OTHER IMPORTANT ENERGY TECHNOLOGIES