Chihuido de la Sierra Negra oilfield is the most important one in Argentina. It is located in Neuquen province.It produces 24,000 oil m3/day from 683 producing wells, and it has been working with secondary recovery since 1994. At present 76,000 m3 of water are injected daily into 545 injection wells.
A method based on the results gotten from core lineal flooding tests is used to predict the injectivity decline rate produced by solids suspended in produced water.
The flood tests were carried out by injecting waters containing different concentrations of suspended solids in order to feature the particle deposition mechanism at middle porosity. Unlike previous studies, this method uses Scanning Electron Microscopy (SEM), which leads to the appraisal of the depth and extent of the core invasion to characterize the kind of filter cake formed.. The impairment mechanism observed is compared to prediction based on the relation between the particle diameter median and the pore throat diameter median.
The experimental parameters obtained from core filtration data are used in mathematic expressions of published models to build the half-life time curve from different concentrations of suspended solids.
The results obtained allowed us to estimate how the water can be treated, and/or state the filtration degree required so as to get the minimum treatment cost that can keep injection in progress and thus assuring the highest production.
This approach also avoids frequent oversizing practices in the design of surface facilities.
The Chihuido de la Sierra Negra area belongs to Neuquina Basin, in Argentina and it is located in Neuquen province; 50 km North-West to Rinc?n de los Sauces and 250 km North-West to Neuquen city (Figure 1). This area covers a surface of about 100,000,000 m2 (10,000 Ha). It produces 24,000 oil m3/day from 683 producing wells. This is the most important field in Argentina.
Oil is produced from Avile Member (Agrio Formation), Superior Agrio Member, Inferior Troncoso Member (Huitrin Formation) and Rayoso Formation. This field was discovered en 1978 and its expansion started in 1979 with Avile Member.
The reservoir structure is an anticline formed by the high Chihuido de la Sierra Negra which develops a large slope towards the east.
The wells have been drilled with an average depth of 1,100 meters (Troncoso-Agrio Fm) to 1,300 (Avile Member).
Waterflood was started in 1994. Fresh water was the injection fluid.
At present 76,000 m3 of water is injected daily into 545 injection wells. The mix between 46% fresh water and 54% produced water is being injected. Pressure well head is 6864.6 kPa (70 kg/cm2). Well injection is distributed in Inferior Troncoso Member, Superior Agrio Formation and Avile Member.
Waterflooding project plans to inject 100% of produced water.
Potential damage mechanisms which can be associated with water injection process in this field include:
Clay deflocculation
Fines migration
Solids injection
Petrographic analysis of core material indicated kaolinite, dolomitic crystals and feldspars in poral system.
