Abstract

PDVSA Múcura District, jointly with the drilling department and the service companies, had been evaluating for several years the use of new technologies that facilitate reaching reservoirs with complex geologies (thin sands, uncertain dip changes, and unconsolidated sands) and improve overall operational efficiency.

Additionally, because of the high viscosity of the oil contained in the Bare field, it was necessary to apply thermal methods to increase recovery factor and achieve PDVSA's 20% target. In such thermal processes, the placement of the wells within the formation is very important, and the use of well placement techniques is expected.

Looking at demonstrating the benefits of the state-of-the-art technology available, specifically for Bare field, but generally for the heavy Orinoco oil belt, PDVSA carried out a pilot project in a thin and very unconsolidated package where a very high drilling rate (up to 1,000 ft/h instant rate) was expected.

The selected sand is named the TL sand, located in the Oficina formation of the Bare field, was initially planned for cold production, but expected the implementation of future thermal enhanced oil recovery processes.

Introduction

The Faja extraheavy oil belt in eastern Venezuela is one of the world's largest heavy oil accumulations, containing an estimated 1.3 trillion bbl of original oil in place, in which 300 billion bbl are considered recoverable oil.

The Orinoco oil belt is located on the southern margin of the eastern Venezuelan basin and runs along the north side of the Orinoco River for approximately 600 km in length and 90 km in width, totaling an area of 55,000 km2. The area is divided, from west to east, into four blocks: Boyaca, Junin, Ayacucho, and Carabobo.

To recover such reserves, PDVSA needed to explore and develop the reservoirs in an economical and efficient manner and increase the current recovery factor. The two major challenges found in the Orinoco belt are the development and exploration of thin sands and the current low recovery factors of approximately 3% expected by primary recovery.

From one side, thin sands in the Orinoco oil belt represent 30 to 40% of the oil in place, which is located in a deltaic sequence with sand thicknesses of less than 20 ft. This challenge is difficult to overcome with conventional technology. The thin sands have to connect larger sections of horizontal sand intervals by drilling geologically referenced trajectories.

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