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Drilling Informatics Research Group is doing research and development for the discovery of new understanding through integration and analysis of multi-scale borehole data taken from scientific drilling projects. In addition to the standard datasets of onboard laboratory, downhole measurements and operational data from rigfloor and ship will extend our understanding on the formation not only after drilling but also in real-time.
As Chikyu expeditions collect more and more drilling, surface and downhole measurements in real-time, we are working to acquire higher quality scientific measurements, and operate more safely and efficiently by interpreting integrated data and adapting drilling operations accordingly. We strongly believe that our studies in the deep oceans will raise the status of ocean drilling science, as well as attract the attention of the industrial sector to work together to overcome the challenges of deep water drilling.
Huge dataset taken from D/V Chikyu expeditions in the last 10 years can be categorize into three groups;
Core-log data integration has been standard process of scientific ocean drilling expeditions, however full utilization was difficult due to the operational limits on wireline logging in the challenging formations, e.g. subduction zones and operations through drill pipe. Availability of conventional wireline logging tools and more use of LWD in Chikyu expeditions opened new chapter in higher quality and more options in measurements and sampling, and hence data integration become more vital for scientific interpretations. In addition, very high resolution X-ray CT measurements on all cores made possible on the centimeter scale accuracy of core internal features in 3D and more on physical properties. Extensive stress analyses were carried out from core and log data taken from the expeditions wherever there are good quality datasets. In partnership with industry, we began our challenge into geomechanical modeling of the deeper part ahead of the drilling.
Our first challenging ultra-deep drilling project, Nankai Trough Seismogenic Zone Experiment- NanTroSEIZE, has no offset well, poor seismic image in addition to the harsh environment (high current, mega-splay fault).
Making well-tie between seismic and log data through synthetic seismograms at well site to the more advanced ways of integrated seismic imaging and quantitative interpretations are part of plan to improve the seismic image and clarify the internal petrophysical parameters or elastic properties in support of safe and efficient drilling operations to reach the target.
Using the existing varieties of geophysical data, multi-channel seismic (MCS), ocean bottom seismometer (OBS), vertical seismic profile (VSP), various technologies (seismic interferometry, reverse time migration, velocity inversion) are in use to make "integrated seismic imaging" to improve the existing poor seismic image in the area in addition to the reprocessing of 3D seismic.
With the need of going beyond the conventional exploration seismology, we are working together with industry experts in "rock physics driven quantitative interpretation" to quantify the lithology, porosity, and using the rock physics models to provide relationship between the elastic and petrophysical properties using the RokDoc application. Operating ultra-deep drilling project in multiple years, updating the seismic image with newly acquired data and adjust the drilling plan accordingly.
Considering the bit-rock interface laws and relationships between rock properties and drilling mechanics, monitoring and analyzing numerous data taken during the D/V Chikyu drilling operations found to be invaluable in various aspects and we are working hard to use it as key measurement in addition to its traditional use as operational monitoring tool. Use of mechanical/drilling specific energy (MSE) after frictional losses corrections to infer drilling efficiency and correlation with scientific measurements, and further extending into bit-rock interactions and effect of mud and pore pressures through intrinsic specific energy (ISE) calculations. Further experiments during the drilling operations will enhance its use.
With enthusiastic engineers willing to carry out any scientific operations onboard Chikyu, exciting drilling experiments are in planning as scientific project or industrial collaborative research to improve our understanding on in situ mechanical properties while drilling. The results will assist better drilling monitoring and planning applications development. Similar and more frequent experiments are planned onshore in combination of key science and drilling engineering objectives.
Even we share ultra-deep targets need common set of sophisticated measurement and drilling technology with industry, scientific drilling projects has more complicated technology requests for their extreme environment targets such as non-contaminated fluid and core sampling, pressurized coring, microbiological/geochemical and borehole magnetic, cross-well EM logging. We began initiatives on those technology developments in partnership with industry and academia.
Drilling experiments, developing sophisticated technology, and geomechanical modeling for High Pressure/High Temperature (HP/HT) are our focus areas for future ultra deepwater challenges coming ahead. We strongly believe that bringing together industry-academia-government collaboration on deepwater drilling solutions will progress in this challenging environment.