Leading the Way to Detailed Geologic Description While Drilling

Pavlovic, Mitch D., Baker Atlas, Houston, TX

The use of borehole image data is an increasingly critical component in evaluating the full potential of a field prior to initiation of the development phase. Over the years, a num­ber of technological advances have significantly improved quality of the wireline electrical and acoustic borehole imaging technology. Recent advances in logging while drilling (LWD) technology allow for high-resolution formation imaging to be successful in wells drilled with both conductive and non-conductive (oil-based) muds. Advancements in LWD measure­ment quality broaden uses from initial while-drilling steering applications (reservoir naviga­tion), into structural interpretation, 3-D fracture system characterization, stratigraphic analy­sis, conventional core description and petrophysics integration, leading the way to detailed geologic description while-drilling.

High-resolution visualization of near wellbore geology while-drilling has many advan­tages including the better shaped borehole at the time of drilling, significantly reduced inva­sion profile effects and 100% circumferential borehole coverage (unlike the pad coverage of micro-resistivity wireline imagers). Above all, real-time imaging capabilities (i.e. images sent to the surface in real-time), optimized in definition given telemetry restrictions, allow for early indication of formation characteristics and may be effectively used for making impor­tant operational decisions.

This paper will review currently available LWD borehole imaging technologies and result­ing geologic applications, including azimuthal density, azimuthal gamma ray and recently introduced micro-resistivity device. Comparison with wireline imaging technologies and conventional core data will be also presented. Field data presented here include data acquired in a range of geological environments and borehole conditions, including horizon­tal wells.