Geosteering in Coiled Tubing Drilling in Carbonates Unlocked by Real Time Characterization on Cuttings
Coiled Tubing Drilling (CTD) is proving more promising in the industry, helping to unlock additional potential in gas bearing reservoirs. The practice allows operators to re-enter existing vertical wells and to drill multilateral horizontal wellbores thus maximizing gas productivity in mature fields. However no Logging While Drilling (LWD) tool is available today to support geosteering in CTD. This is a key challenge in industry to unlock CTD potential to geo-navigate through sweet spot layers. Logging While Drilling (LWD) tools such as Nuclear Magnetic Resonance (NMR), acoustic, resistivity, pulsed neutron, etc. while used in conventional drilling to actively support geosteering operations, until now are un-available in the industry for CTD (hole diameter about 3 inches) applications. Direct characterization of cuttings could play, in this context, a pivotal role in support of geosteering in CTD operations. The proposed technology called Advanced Automated Cuttings Analysis (AACA) is a novel approach that has the potential to boost CTD deployment and increase recovery from mature gas fields. This work describes how Advanced Automated Cuttings Analysis (AACA) using a wellsite deployable SEM-EDS system could be used to create a detailed lithotype scheme focusing on mineral texture and composition for a shallow carbonate interval that has a strong diagenetic over-print, due in part to dolomitization, which erased the pre-existing biostratigraphic signature. In addition the GR signature along lateral wells drilled into this interval is typically flat, due in part to the typically homogeneous mineral compositions encountered. The lithotype scheme was created using data generated from a wellsite deployable Scanning Electron Microscope-Energy Dispersive Spectroscopy (SEM-EDS) system designed for the collection and analysis of quantitative mineralogical and textural data from cuttings. Data generated by the Advanced Cuttings Analysis technique has the potential to help with CTD geosteering decisions that could increase wellbore contact with the known sweetspot thus improving a well’s total gas productivity.
AAPG Datapages/Search and Discovery Article #90332 © 2018 AAPG International Conference and Exhibition, Cape Town, South Africa, November 4-11, 2018