HOLA14 - 190 SEISMIC INVERSION APPLIED TO GEOLOGICAL AND OPERATIONAL MONITORING OF DRILLING HORIZONTAL WELLS IN THE CARABOBO 5 AREA OF THE FAJA PETROLÍFERA DEL ORINOCO Authors: Ontiveros, Tulio; Herrera, Verónica; (Petroindependencia; PDVSA Afilliate); Meza, Ronny (ARC Solutions) This paper has been selected for presentation and/or publication in the proceedings for the 2014 Heavy Oil Latin America Congress. The authors of this material have been cleared by all interested companies/employers/clients to authorize dmg: events (Canada) inc., the congress producer, to make this material available to the attendees of HOLA2014 and other relevant industry personnel. ABSTRACT The Faja Petrolífera del Orinoco de Venezuela (FPO) holds the world largest extra heavy oil reserves. Its reservoirs are characterized by a great net to pay ratio with porosities values over 30%, and permeabilities greater than 10 Darcys. The Morichal member is the most prolific reservoir of the Oficina Formation, comprises fines and sands being deposited under a braided fluvial regime, of variable thickness (10 to 80 ft) and shaliness. Petroindependencia (PI), a new developing oil company for the FPO, has been constituted with the main objective of draining these important extra heavy oil reserves in the Carabobo 5 Block, as part of its exploitation business plan within the next 25 years targeting a 400 MMB/D production rate plateau. All the available technical information (structural interpretation, well logs, core data, among others) was used to build the Sparse Spike acoustic impedance attribute, which has been the key tool to locating and positioning wells along the main depocenter in the first three cellars in PI; named as: PI-A03, PI-B03 and PI-C03. In this sense, the first production well (VTR-001) of Petroindependencia was a successful drilling, with the operational monitoring based on the Sparse Spike acoustic impedance attribute together with a shale volume model. This methodology was essential in predicting lateral facies changes on the proximity to the well trajectory during the drilling of its intermediate and horizontal section, providing a guidance to guarantee the well location and trajectory reaching, and contacting the reservoir with 95% certainty. Keywords: Seismic Inversion, Faja Petrolífera del Orinoco, Sparse Spike acoustic impedance attribute; Carabobo area. INTRODUCTION In the oil industry is a very common practice to rely on amplitude attribute information during horizontal drilling activities, aiming to follow a particular reflector associated with reservoir lithology. In the Faja Petrolífera del Orinoco, the main production unit of the Oficina Formation; is the Morichal Member comprising fluvial-transitional unconsolidated sands. In this interval, the sedimentation evolution has generated a stacking pattern of braided channels with variable thickness, and in some cases these channels are eroded or overlapped with other channels, giving rise to a multi-story channel system. These reservoirs characteristics represent a challenge in horizontal drilling because the lateral facies changes are not easy to identify with only the seismic amplitude attribute. In this way, it was necessary to develop a strategy to identify lateral facies changes in each internal unit of Morichal Member. The strategy was focused in building a seismic attribute powerful enough to honor both, well log information and lateral facies variations. The seismic attribute selected was Lineal Programing (LP) Sparse Spike Impedance Inversion, since this attribute is a tool that offers a quantitative way of incorporating the available prior information into model building, and aids the interpretation of the seismic data. It may lead to a result that offers a high resolvability and a better link between seismic data and lithology (Li, 2002).