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

Abstract

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.

Study on Viscosity Reducer Flooding Technology for Deep Low Permeability Extra Heavy Oil Reservoirs

“…Experimental steps are as follows: ① connect the experimental device according to the experimental flow chart, and inject formation water into the microscopic glass etching model with the flow rate of 0.03 mL/min, until the water phase distribution of the model is uniform and continuous water drops appear at the outlet end; ② the experimental oil was injected into the microscopic glass etching model until the oil phase distribution in the model is 2 Geofluids uniform and continuous oil drops appear at the outlet end; ③ inject formation water into the microscopic glass etching model with saturated oil until water cut at the outlet reaches 98%; ④ inject viscosity reducer into the microscopic glass etching model until there is no oil dripping out at the outlet end.…”

“…Deep low permeability extra heavy oil reservoirs refer to the oil reservoirs with buried depth more than 2200 m, reservoir permeability lower than 300 md, and crude oil viscosity greater than 10000 mPa•s at 50°C. Deep low permeability extra heavy oil reservoirs have the characteristics of deep burial depth, high formation pressure, low permeability, and poor crude oil fluidity, which leads to great difficulty in development and low productivity of a single well [1][2][3][4][5][6][7][8][9][10]. At present, there is no clear and reasonable development method for the economic and effective production of this type of heavy oil reservoir.…”