Geosteering and Mapping of Complex Reservoir Boundaries Using an Integrated Data Approach

Abstract

Most production wells currently drilled in the North Sea are in complex geological settings. In order to place the wells safely and effectively, drilling a successful production well requires an advanced technology and integrated proactive reservoir navigation approach, in addition to multiple data driven answer products from downhole tools. Extra deep azimuthal resistivity logging while drilling (LWD) tools can detect boundaries up to 30 m away from the wellbore given optimal resistivity conditions. Combined with multicomponent inversion modelling (MCWD), the data acquired are used to map multiple boundaries, individual sand bodies, reservoir thicknesses, and lateral reservoir changes. Borehole images aid in geosteering and are used to steer up or down based on structural boundaries identified on the image. Using wired pipe technology that provides telemetry rates good enough for memory-resolution data, the full resolution electrical image is available while drilling. Despite complex reservoir geometry in both external boundaries and internal sedimentary structure, it was possible to succesfully geosteer by using an integrated geosteering approach. Through MCWD inversion, it was possible to track a thin, highly resistive layer at the roof for much of the reservoir, which allowed for proactive geosteering, optimizing wellbore placement and mapping of reservoir volumes.

A review on the applications of nuclear magnetic resonance (NMR) in the oil and gas industry: laboratory and field-scale measurements

“…In general, the LWD-NMR magnets are design to reduce the effect of the radial vibration on T 2, achieving one-directional measurement and increasing the logging speed. The key advantage of the LWD-NMR is the ability to acquire the advanced information evaluation such as continues mobility information of the formation in real time during the drilling operation (Selheim et al 2017).…”

“…The comprehensive program incorporated the data from Formation Pressure While drilling (FPWD) for real-time detection of low mobility zone penetration which will help in adjusting the trajectory of the well. Also, the program utilizes the data from LWD-NMR for heavy oil detection as it gives a continuous information of the fluid mobility of the formation being drilled (Selheim et al 2017) where the placement of water injector is unlikely. The main purpose of the LWD-NMR was identifying the tar mat zones and quantify the fluid viscosity (Akkurt et al 2010).…”

A decision support system for multi-target geosteering

“…In the proposed geosteering workflow, shown in Figure 1, real-time decision support is based on Bayesian inference from a probabilistic geomodel that is continuously updated. and Denichou, 2015;Hartmann et al, 2014;Selheim et al, 2017) but are generally not available in the open domain, only as paid services. The main contribution of this paper is the DSS and not the modelling of the measurements.…”