Titre du document / Document title

Rospo mare field : A unique experience of heavy oil production with horizontal wells in a karst reservoir in presence of a strong tilted hydrodynamism

Auteur(s) / Author(s)

GAUCHET R. ⁽¹⁾ ; CORRE B. ⁽²⁾ ;

Affiliation(s) du ou des auteurs / Author(s) Affiliation(s)

⁽¹⁾ Elf Idrocarburi Italiana spa, ITALIE
⁽²⁾ Elf Aquitaine Production

Résumé / Abstract

Rospo Mare field is located in the Adriatic sea (Italy) 20 km off the Abruzzes coast, at a mean water depth of 80 meters. The joint venture ELF-AGIP started its development in 1982 with a pilot. For years now, this field is producing heavy oil from three platforms and twenty eight wells (two verticals and twenty six horizontals). It is then one of the longest production history with horizontal wells actually available in the world. The challenges for the development of Rospo Mare field have been numerous and various in their nature as described as follows : . the reservoir is a karst, essentially conductive, which is extremely different from a conventional reservoir. This is one of the reasons why a development with horizontal wells has been decided in order to increase the drainage area by intercepting as many fractures as possible with a limited number of wells. Also, such a reservoir cannot be simulated with the usual techniques. Therefore, several approches as well as in the petrophysical parameters determination than in the reservoir simulation techniques, have been attempted to better describe the sweeping mechanism during the production period, . the oil is very viscous (437 cPo at reservoir conditions) and heavy (0.962 g/cm³ at reservoir conditions), which obliges to take care of the thermal and friction problems in the well during the production. This aspect may be crucial in some conditions as described in this paper, . the water/oil contact is tilted, and a strong hydrodynamism has been identified (no pressure decline). However, the inlets and outlets of the system were totally unknown. A new approach has been recently conducted using a fine gridded model to better determine this system, and then to simulate the evolution of the water/oil contact during the production. It has also allowed to localize the oil actually remaining in place, and then to study the influence of several future production scenarii on the evolution of the water/oil contact, . for not trapping oil in the reservoir and not to separate the water at surface because of the weak difference between the oil and water densities at these conditions, it has been decided to produce each well of Rospo Mare at its critical rate. The use of horizontal wells has allowed to increase the potential values of these critical rates in comparison with the ones which would have been obtained with vertical wells. In addition, with such a production philosophy, it has been shown theoretically that the critical rate can be written as a parabolic function of the cumulative production. This model, based on the stability of the water cone under the well during the production at its critical rate, has allowed to match the production history and then to extrapolate it for the next years, . the oil is also undersaturated with a very low saturation pressure (5.4 bar for a reservoir pressure of 130.4 bar) and a GOR of 2.1 m³/m³. As a consequence, the well head flowing pressure is less than 10 bar and very sensitive at water presence. It has been shown that, due to the nature of the reservoir, the surface pressure can be restored removing the water present inside the well by injecting one well volume of oil. The aim of this paper is then to summarize the main steps of this long understanding process of the Rospo Mare behavior, and to highlight the innovative solutions developed in each area. Also, it is shown how all of these aspects are integrated in the daily regulation of the production in order to optimize the final recovery.

Source / Source

Congrès
Technology integration for innovative solutions : Milan, 22-24 October 1996
EUROPEC : European petroleum conference, Milan , ITALIE (22/10/1996)
1996  , pp. 473-482 (14 ref.)

Langue / Language

Anglais

Mots-clés anglais / English Keywords

Oil field ; Offshore production ; Reservoir engineering ; Karst ; Reservoir rock ; Horizontal well ; Hydrodynamics ; Production ; Porosity ; Drainage ; Oil water contact ; Modeling ; Italy ; Adriatic Sea ; Europe ; Mediterranean Sea ;

Mots-clés français / French Keywords

Champ pétrole ; Exploitation marine ; Réservoir engineering ; Karst ; Roche magasin ; Puits horizontal ; Hydrodynamique ; Production ; Porosité ; Drainage ; Contact huile eau ; Modélisation ; Italie ; Mer Adriatique ; Champ Rospo Mare ; Europe ; Mer Méditerranée ;

Mots-clés espagnols / Spanish Keywords

Campo petróleo ; Explotación marina ; Ingeniería reservorio ; Karst ; Roca reservorio ; Pozo horizontal ; Hidrodinámica ; Producción ; Porosidad ; Drenaje ; Contacto aceite agua ; Modelización ; Italia ; Mar Adriático ; Europa ; Mar Mediterráneo ;

Localisation / Location

35400006808704.0450