Well Testing Improvement Using Nitrogen Lifting in Shushufindi Field: Accelerating Well Response and Transient Data Quality

Abstract

Shushufindi field is the largest field in the Oriente Basin in Ecuador and is located 100 miles east of Quito. It contains 3.7 billion barrels original oil in place (OOIP) and represents 10% of country's production. Determining reservoir properties using evaluation with hydraulic pumping for well testing has been a common practice in Shushufindi field since development in the early 1970s by Texaco Gulf Company and continuing in recent history with state company Petroamazonas.Due to the high level of depletion and reservoir characteristics, obtaing good quality data from well testing is a challenge, and if a decision is made based on the wrong information, it could have a severe negative impact on the asset. Ambiguity in the results of well testing with a hydraulic pumping method can stem from failure on downhole shut-in that allows the development of wellbore storage, which in turn would lead to difficulties for well test interpretation, accurate flow capacity/ productivity evaluation, fluid sampling, etc.To clarify all well testing concepts and results, a new procedure was developed for well testing in this field that uses a combination of drillstem testing tools, coiled tubing, and nitrogen lifting. With the developed method, the test is combined and continually conducted to test flow rate and drawdown buildups including downhole shut-in, providing reservoir and fluid parameters for a better evaluation and for artificial lifting design.This paper will present a study of the implementation of this new method, covering the areas of well evaluation and the outstanding results in accelerating well response. The procedures are generally easy to follow and to understand and have an impact in reducing rig time and nonproductive time and result in a faster return of the well to production (workover). The pilot showed excellent results in obtaining reservoir property measurements that were validated by reservoir modeling and production history. The process is robust, repeatable, and applicable to other fields with similar characteristics.