Advanced Gas Analysis Meets Geoscience Solution in Norway Field: The Insights of a Holistic Approach

Abstract Equinor has a complex faulted field in Norway with expected different fluid contacts. To maximize the reservoir understanding a geoscience approach is applied for this project. The utilization of Ultra Deep Azimuthal Resistivity (UDAR) technologies is typically sufficient to control the vertical and lateral limits of a reservoir and unveil potential flooded intervals and oil water contacts (OWC). However, the differentiation between oil and gas by just LWD and UDAR data is not possible. This study demonstrates three geoscience areas contributing for early decision making while drilling the Brent Group formation. The cost-effective solution in this project was the implementation of advanced mud gas (AMG) using a constant volume and constant temperature (CVCT) extractor with advanced gas chromatograph to analyze species such as methane to octane. Correction for recycling gas and extraction efficiency correction (EEC) of methane to pentane species were also applied in real time (RT). The gas ratios curves were the first look of the PVT for this well, therefore the gas oil ratio (GOR) prediction based on the model proposed by Yang et al., 2019 were also available and provide reservoir insight while drilling. The High-Resolution ultrasonic image tool was used to detect bedding, fractures and faults planes post-drilling, and in conjunction to UDAR results several diagrams such as Stereonet plot and curtain sections were displayed. Additionally, an ultrasonic caliper tool was used to identify the borehole shape. The sandstone bedding plane orientation showed several trends inside the whole interval and most of these changes were associated with faulted intervals and validated with Geosteering inversion model. The fault system understanding is important in this basin since it contains a western graben created by several faults stepping down preserving Upper Brent. Petrophysical analysis complements and supports the results from AMG, UDAR and borehole image analysis. The basin setup is helpful to understand the fluid distribution in the petroleum system. From a petrophysical viewpoint, water saturation from resistivity logs and neutron-density separation helped to estimate fluid types, and it was validated with AMG. The identification of 300m of water flushed zone, later confirmed by production, shows the holistic methodology implementation allowed a review of the fluid distribution in the well results. This paper demonstrates the contribution of the race to digital transformation and enabled reservoir characterization while drilling.