ABSTRACT

This paper describes the evaluation of a fluid containing nano-materials with high adsorption capacity for Asphaltenes inhibition in a volatile oil field in Colombia. Asphaltenes precipitation has been identified as one of the most potential damaging mechanism affecting the well productivity in Cupiagua Sur Field. Before this work traditional techniques have been tested in the field for asphaltenes inhibition. The goal of the injection of nano-fluids containing nano-particles of alumina with high surface area (>120 m2/g) is to absorb the asphaltenes before being flocculated and carry them with the condensate avoiding precipitation near the well bore.

In the first stage of this work, lab testing, the adsorption capacity of alumina nano-particles for the asphaltenes produced in the field was evaluated, next, the nano-fluid containing nano-particles was evaluated in the Mirador formation plug cores by performing flowing core tests at the reservoir conditions. Returns of the relative permeability curves were quite good, improving Ko from 0,09 md to 6,13 md which enabled us to recommend the application of this nano-fluid in the well CPSXL4.

For the Field Application, the job was designed by forcing 220 bbl of nano-fluid within a radius of 8 ft. After the job, through monitoring with SARA analysis in produced fluids and the residual tracking of nano-particles as well. Maintenance of asphaltenes concentration in the produced fluids has been observed. Also, significant gain in the oil and gas production has been reported, with more than 100,000 bbls of cumulated gain production in only 4 months after the job was performed. Results may be promising and now it is possible to extend application of nano-fluid in other wells in this field.

INTRODUCTION

The Cupiagua Sur field is located 110 kilometers northeast of Bogota in the foothills of the eastern mountain chain of the Colombian Andes, close to other fields discovered in this area such as Floreña, Pauto, Volcanera, Recetor, Cupiagua and Cusiana (Fig. 1). Despite the fact that Cupiagua Sur is very close to Cupiagua, this reservoir is totally independent and separate. It is formed by a back thrust structure with several reservoir pressures, properties and contact fluids.

Cupiagua Sur is a compositional volatile oil reservoir with an average API gravity of 38°; there is no free gas cap at initial conditions. The main formations are Mirador and Barco which are quite similar about petrophysical and fluid properties (average permeability is 21 md and average porosity is 6.5%).

It is a prolific oil field that in fifteen years of production has recovered 88 MMstb gross out of 189 MMstb original in place from Mirador and Barco reservoirs in a developed area with four producer and two injector wells.

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