Publications

All too often the inability to reasonably forecast the effect of changes in the a priori information used in the well planning phase results in unplanned events such as side-tracks, kicks, losses and other drilling issues that ultimately end up in project cost overruns. The critical factor is the ability to accurately integrate data sets at different scales (e.g. lower-resolution seismic to higher-resolution logging or LWD measurements) within a time frame that is fast enough to correct the well trajectory in real-time. Seismic Guided Drilling (SGD) technology delivers just such functionality by integrating Imaging and beyond Imaging Products that share the same Earth Model. In SGD*, we incorporate WL data and real-time well measurements from LWD / MWD data into a prestack anisotropic depth imaging workflow to achieve rapid 3D-updates of subsurface earth models (velocity and anisotropic parameters) and image volumes (seismic, interpretation, lithology, pore pressure and fracture gradient). It has two major components: Baseline Earth Model construction using Rock Physics Guided Migration (RPGMIG*) Technology (Dutta et al 2011) and a Rock Physics based model for Pore Pressure analysis (Dutta et al 2006) that uses the same earth model as that for depth imaging. SGD* delivers a unique look-ahead capability – typically, 500 – 700 m+ ahead of the bit and look-around images in a Volume of Interest (VOI) – typically 5 by 5 km (25 km2) around the well, all in real-time. Thus, it enables drillers to make decisions (mud weight management, casing point decision, management of * SchlumbergerWesternGeco, Houston, Texas, USA ** ONGC, Mumbai, India drilling hazards and trajectory to reach drilling targets) in real-time. SGD* is NOT SWD- Seismic-While Drilling technology (for example, SeismicVISION tool in the industry). We note that in SGD*, no new seismic data is acquired during drilling, unlike SWD– instead, we update a Baseline subsurface model many times during the drilling time using the same seismic data but calibrated by real-time data from the well being drilled. We shall illustrate how the technology delivers using real examples from several wells.