Near-Real-Time Tracer Data Optimizes Well Cleanups in the Nova Field

Abstract

_ This article, written by JPT Technology Editor Chris Carpenter, contains highlights of paper SPE 214351, “Near-Real-Time Tracer Data From the Onsite Tracer Analysis in the Nova Field,” by Alireza Roostaei, SPE, Ehsan Nikjoo, SPE, and Ali Nadali, SPE, Resman, et al. The paper has not been peer reviewed. _ This paper describes how near-real-time tracer data from an onsite tracer analysis enabled the operator to interactively optimize two well cleanups in the Nova field. The tracers provided key information on the cleanup progress in different zones, which enabled the operator to make informed and fast decisions to maximize well-cleanup efficiency while minimizing rig time and cost. Introduction The Nova field is in the northeastern North Sea. Reservoir sands are at depths of 2500–2800 m, with a pressure of approximately 290 bar and temperatures up to 110°C. The field will be operated with six wells—three oil producers and three water injectors—with an injector/producer pair in each of the main fault compartments. The authors, in the complete paper, show the value of inflow tracer data during the cleanup phase of two producers (X-3H and X-4 AHT2) in the field. Well-Cleanup Challenges and Monitoring Requirements The main challenge is to ensure that the well is sufficiently cleaned up at the zonal level while rig time and cost is minimized. Therefore, a monitoring method is required that can provide real-time data of cleanup progress in different zones. The data enables the operator to make informed decisions while the cleanup is ongoing, allowing optimization of well cleanup when needed. The risk-free and cost-effective inflow tracers with onsite analysis provide near-real-time data on cleanup efficiency in different zones. Because the Nova wells are equipped with inflow tracers, the operator used this data to understand the wells’ behavior and make real-time decisions to increase cleanup efficiency and zonal productivity. Equipment and Processes Inflow tracers are integrated in polymer rods that are stable in a wide range of well conditions. These inflow (in-well) tracers have been tested and designed in different hydrocarbon fluids and a broad temperature range (20–200°C). In the Nova field, unique oil and water tracers were deployed in the lower completion. These intelligent tracers remain dormant until they come in contact with their target fluids. Oil-based mud (OBM) was used as a lower completion fluid in the Nova oil wells; thus, the release of oil tracers began with contact with OBM. The polymer tracer rods are installed in the completion before running in hole; therefore, no downhole intervention is required. Each unique oil-tracer system consists of several polymer rods distributed evenly around the pipe in a carrier. The venting configuration of these systems is shown in Fig. 1. Once the tracers are released from the polymer rods, they will travel to surface with the fluid flow. At surface, samples are taken with different sampling frequencies depending on the monitoring objectives. The samples then are analyzed in a laboratory to identify and quantify tracers. The samples can be analyzed onsite or offsite.