Real-Time Automated Formation Evaluation Using the Integration of Logging While Drilling and Advanced Cuttings Analysis

Abstract

Real-time formation evaluation is performed utilizing data acquired in the field from logging-while-drilling (LWD) tools and mud-logging data equipment. The data is then interpreted in the office by petrophysicists and log analysts. Unlike traditional log interpretation analysis, automated log analysis using statistical models provides continuously improving results based on trained and supervised models. Most automated log analysis approaches utilize historical data and incorporate multi-well data to improve the petrophysical evaluation. The objective is to reduce the evaluation time and reduce uncertainties based on trained models. Real-time LWD and surface data logging are primarily used for formation evaluation and well placement in high-angle and deviated wells. Log analysis is usually performed by petrophysicists and is not in actual real time. Providing the interpretation in actual real time provides important data for geologists, well placement engineers, and drilling engineers to improve the reservoir contact and productivity in addition to operational cost reduction. A selection of models has been used for automated lithology predictions. Five logs have been used in total utilizing basic LWD data (gamma ray, density, resistivity, photoelectric, and neutron-porosity measurements). In addition to the LWD data, advanced cuttings analysis has been performed on site in real time on multiple wells. X-ray fluorescence (XRF) provides elemental data while X-ray diffraction (XRD) provides direct mineralogy measurements. The automated lithology interpretation provides quick assisted lithological interpretation and quantifies uncertainties with minimal human input. Basic LWD data were used for the automated lithology interpretation. The predicted lithology was verified against interpreted mineralogy from XRF and direct mineralogy from XRD measurements. Simulation of the results and the real-time QC process are very promising. Quality control processes were followed for the data acquisition where XRF computed gamma ray was used to verify the depth control for XRF and XRD data with reference to the LWD measurements. Real-time automated log analysis provides a step change in formation evaluation, providing critical information to well-placement and drilling engineers as well as an automated quality-control measure for data acquired in real time.