An Integrated Reservoir Analysis to Evaluate Water Flooding and Define Remaining Potential of the Teak Field, Trinidad & Tobago

Abstract

Teak, Samaan and Poui (TSP) are mature fields off the South-East coast of Trinidad, which currently produce near to 14,000 bopd with an average Water Cut of 85%. Their production started in 1972 and peaked at 143,300 bopd in 1978. The 0/1L Sand, in the Teak field, has accumulated over 72 MMBO and displays a low reservoir pressure, yet it still contributes with almost 10% of the total current production of TSP. Secondary recovery was implemented in TSP since the late 1970s; some 21 MMBO are estimated to have been recovered from Sand 0/1L, in the Teak Field, thanks to the Water Flooding campaign, which was active between 1977 and 1998. Repsol E&P T&T ltd., operator of the TSP asset, has identified the potential for increased oil recovery by means of waterflooding. Evaluating injectivity of those wells that are available for injection is the starting point of the current strategy. Additionally, Repsol's Technology Center in Madrid has been contacted to perform a specialized water characterization and compatibility analysis, which is currently ongoing. The focus of this paper however is the subsurface. Initially, the reservoir pressure and production behaviour has been analysed to estimate pressures and analyse block connectivity. Together with this a first one-dimensional material balance model was created to preliminarily evaluate performance. A multi-layer Water Flood pattern simulator, which has proven very useful in understanding past performance, was one of the main tools of the analysis. Finally, a full 3D model is currently being tuned to obtain definite production profiles. Furthermore, the value of detail model preparation was proven by the identification of potential workover candidates. Remaining oil was identified in bypassed areas and in zones previously interpreted as gas bearing. The main goal of this paper is to understand past performance of waterflooding as the key to defining the remaining potential.