Fluid Logging and Analysis in Real Time, an Application for Shushufindi-Aguarico

Abstract

The Oriente Basin is located in eastern Ecuador at the Amazon rainforest. Shushufindi-Aguarico field is one of the most important fields in Oriente Basin with over 12% of the national production; the main hydrocarbon reservoirs are located inside the Cretaceous formations Napo and Tena. In spite of being a mature field in production since the beginning of 1970s, Shushufindi-Aguarico field still presents various formation evaluation challenges that can potentially be explored to enhance its productivity. In order to improve fluids characterization in a recently developed area at NorthWest of the field, a new reservoir evaluation technology, Fluid Logging and Analysis in Real Time, is introduced to obtain a continuous log of quantitative composition of hydrocarbon and an improving in the pay zones analysis from gas presence in the mud while drilling. The prospective intervals determination within the productive reservoirs is performed while drilling with cuttings analysis and chromatography evaluation in real time. This evaluation is based on Gas Ratio Method, which uses the relation between heavy, medium and light gases to identify porous rocks with hydrocarbon presence. The prospective intervals determination using Advanced Surface Fluid Logging technology gives more precision to identify thin beds by eliminating the recycled gas effect than conventional mud logging. In addition, the Advanced Surface Fluid Logging provides fluid composition in the C1-C5 range analogous to the PVT single phase composition. The fluid composition achieved in the main target zone exhibited a close correlation with a convention PVT from a recent offset well. This paper presents a case study where ASFL technology was tested on a Shushufindi well highlighting valuable benefits, with better pay zones definition in the challenging geological environments encountered in the Shushufindi-Aguarico field. The reliability of the data provided is demonstrated by the good correlation amongst the Fluid Logging and Analysis in Real Time composition recorded in the main target zone and a recent PVT composition from a nearby offset well.