Potential Application of Thermal Processes To Improve Extra Heavy Oil Recovery: A Simulation Numerical Study from Orinoco Oil Belt, Boyaca Area

摘要

This study aims to evaluate a wide variety of thermal processes in Boyacá area, located in Guárico state in the Southern flank of the Orinoco River, Basin of Venezuela, which holds an extension of 1247 km2 of extra heavy oil with an API Gravity between 4-8 (API: 4-8), porosities between 25-32% and permeabilities of 2-15 Darcies. Block 06 produced through 7 wells, two of which did not produce, while others two produced by Cyclic Steam Stimulation (CSS) as a test. Results from these tests indicate success in one well which had an accumulated oil production of 26179 STB in one cycle. Synthetical correlations were used in order to estimate fluid and rock properties, considering data obtained from nearby blocks. Geoestatistical model resulted from a refinement of the entire Boyacá area. This new model was classified in three ranges of continuous net sand thickness. First step involved an analysis of this block using “screening criteria” to determine which thermal process was appropriated to apply. As a result, steams flooding based technologies were recommended due to their power to increase the recovery factor in heavy and extra heavy oil reservoirs, providing the required heat content of steam (1200BTU/lb). A following step was building sector models in order to simulate the production history in one of the CSS wells, to simulate each thermal process and to optimize operational parameters. Subsequently, CSS and SAGD (Steam Assisted Gravitational Drainage) were simultaneously simulated. According to these simulations, it is feasible to maximize the recovery of this block up to 30% using this kind of technology. Furthermore, the best economical indicators were obtained through a combination of CSS+SAGD resulting in a net present value of 1521 M$, internal return rate of 15%, operational costs of 16 $/Bbl for an economical horizon of 20 years.