Orinoco Oil Belt Well Construction Using "Wells-In-Series" Technology With Horizontal And Multilateral Trajectory

Abstract

Abstract The Orinoco Oil Belt, located in the southern part of Venezuela, is a gigantic reservoir of 55,000 sq. Km, which contains accumulations of heavy and extra-heavy hydrocarbons of 1,200 MMM barrels of oil in place, and final recovery of 270 MMM barrels. The first well, Canoa N°1, was drilled in 1935. At that time, various multinational companies started exploratory activities in the area. However, due to the oil characteristics, such as low gravity, high viscosity and metals content, the interest of these companies decayed rapidly. Finally, in 1977 the Executive Branch, through the Ministry of Energy and Mines, assigned the responsibility to PDVSA of planning and executing the necessary activities to evaluate and develop the energy resources of Faja. During the period 1978/1983, an intensive exploration and evaluation program was developed1, including drilling about 1,000 wells, which resulted in a detailed evaluation of the regional geological model, the reservoir characteristics and the crude physicochemical properties. The facility requirements for oil transportation and processing were analyzed as well. Simultaneously, a territorial ordaining of the entire southwestern part of the country was carried out through an Agreement among PDVSA and several Government institutions. In the early 90 s, as a result of the hydrocarbon worldwide demand forecast and the huge heavy and extra-heavy crude reserves in the Faja, PDVSA, in accordance to the premises established by the Government, decided to promote the creation of Strategic Associations to carry out projects with the aim of fully developing the Faja. In 1990 horizontal drilling was started which in the end would make the development schemes profitable. Likewise, several projects such as the Experimental Production Blocks in Cerro Negro, Steam Drive Project in Jobo, Guanipa 100, Zuata - San Diego and Hamaca -El Pao, contributed with an important part of the technical information required on well spacing, production mechanisms, well drilling and completion and artificial lift. In 1991, PDVSA began negotiations in accordance with the Venezuelan Oil Opening International Plan (the "Apertura") to attract foreign capital and reach an agreement on the Strategic Associations for the combined exploitation of extra-heavy oil in the Oficina Formation of the Orinoco Oil Belt for a period of 35 years each. The area assigned to the four existing Associations is approximately 1,750 sq. Km in Monagas and Anzoátegui States, which contains accumulations of extra heavy oil estimated in 100 MMM bls of oil in place with a final recovery of at least 11 MMM bls. The beginning of the negotiations was framed originally in gathering information on Seismic, Well Logs, Tests, existing Analysis and the recommendations given by PDVSA to change the exploitation pattern from Continuous Steam Injection to horizontal drilling under cold production, based on the experience of the horizontal wells drilled in the Bare and Cerro Negro fields, located in areas of the Orinoco Oil Belt. Each Association drilled Confirmation Wells and obtained information related to actual production rate, fluid characteristics and current pressure of the assigned areas. These figures were confirmed in the early production phase with the drilling of Stratigraphic wells in some of the pads, allowing to plan the Integrated Studies of Seismic, Sedimentology, Geomechanic, Characteristic of the Fluids, Risk Analysis etc. The harmonic development of these initial studies allowed the implementation of a drilling plan, which included issues such as wells - in - series with horizontal and multilateral trajectory, contracting and planning Purpose - Built Rigs used for these operations and services rig contracts, to support the completion of the number of wells per pad.