From Screening to Drilling – Planning a Drilling Campaign in an Offshore Mature Field: A Case Study of TSP Field, East Coast Trinidad

Abstract

Repsol (operator), together with partners Petrotrin and National Gas Company of Trinidad and Tobago, took over operations of mature fields Teak, Samaan and Poui (TSP) Offshore Trinidad at the end of 2005. With the intention of planning further development in the TSP reservoirs (comprising more than 10 vertically stacked main units, highly compartmentalized reservoirs with complex tectonic geometries) an indigenous comprehensive field evaluation was required. Thus, a sand-by-sand Screening Project was carried out with the main objective of identifying the reservoirs with maximum potential so as to direct further technical effort on specific reservoirs for early monetization of reserves. Based on the results of the sand-by-sand screening project, a prospect validation project for Teak Field was initiated – consisting of extensive field data acquisition, detailed interpretation and modeling workflows, adapted to the particular needs of mature fields. Several incremental opportunities identified during screening were validated and detailed modeling was performed to support further development. On completion of this effort, the company acquired a holistic view of the asset in terms of projects and its remaining resources, so a drilling campaign was envisioned and planning started. The selection of drilling candidates was not a straight forward process. The number of opportunities had been reduced considerably from the opportunity category to the actual well candidates. Several disciplines developed specific workflows to overcome the challenges, for example: risk assessment for infill opportunities and probabilistic forecasting (Subsurface), trajectory designs including anti-collision, drilling through depleted sands, torque and drag analysis and selecting a suitable rig for the field and production platform conditions (Drilling Engineering); among others. At the time of submitting this paper, two drilling rigs are moving onto the acreage to start drilling these opportunities by the end of 2013. This paper outlines the different challenges faced, as well as case studies of the evolution and maturation from the screening to the drilling stage of some of the prospects.