Approximately 30 relative permeability modifier (RPM) fracturing treatments performed in Colombia will help establish consistent, reliable best practices for future applications. Some of these treatments combined scaling inhibition stages to maintain production enhancement, in spite of high or medium formation water scaling tendencies. Because the water-injection system is significantly dynamic in these fields, new injection water channels were communicated with producer wells after RPM-fracturing treatments, reducing scaling inhibition requirements and RPM effectiveness for water production management.
The objective of combining RPM and fracturing treatments was to increase oil production over time through effective water production control techniques.
Evaluations of the effectiveness of both general and specific treatment processes and service are available in the industry. However, data for the analysis of RPM-fracturing treatments presented in this paper was obtained in two basic procedures:The workover operating efficiency (WOE) index was established to evaluate fracturing effectiveness (total fluid production increase) and RPM effectiveness (water-oil ratio [WOR] reduction). The WOE index quickly analyzes all treatments and identifies the best-performing ones based on two factors:production-related WOE indexes higher than one, which is the maximum production rate after treatment vs. the minimum production rate before treatment, andWOR-related indexes lower than one, or the minimum WOR after treatment vs. the maximum WOR before treatment.This analysis can quickly define the best and worst performances by evaluating individual fracturing effectiveness and individual RPM effectiveness.The reservoir-performance analysis is a cyclical and detailed process that does not focus on individual wells but rather analyzes the entire reservoir. This stage consists of an extensive analysis that involves reservoir characterization, well testing and production history, completion design, stimulation operation design, and stimulation operation execution and feedback.
Because this analysis was so extensive, it was applied only to the best- and worst-case scenarios (two different fields) in which combined RPM-fracturing/scaling inhibition treatments had been in effect for more than 2 years. Those two fields presented some similarities in terms of producing-zone depth, reservoir character, reservoir fluid properties, and water-injection systems.
Both general and specific processes for treating and servicing wells have been evaluated for effectiveness by the industry. Applying the results of the two analyses presented in this paper, best practices are now defined for future well selection, treatment design, and operation execution for combined RPM-fracturing/scaling inhibition treatments.
Introduction
An average of 15 RPM-fracturing treatments for each of two fields was evaluated for this study. These fields, identified as Fields A and B, exhibit many similarities and only a few differences. Both are sandstone, producing formations with typical average clay minerals content. Producing zones are average with similar depths and bottomhole temperatures. The collection, review, and analysis of these jobs has been sufficient for defining best practices for future jobs on similar wells.
A detailed analysis of the entire reservoir and field was performed for two scenarios: the best and the worst case. These cases were defined according to:the highest production increase ratio as a moving average during 3 months,the highest incremental production after 6 months, andthe lowest water-oil ratio decrease as a moving average during 3 months.1 Additional details and concepts for the two basic analysis procedures based on well performance are provided in the following sections.
