Operational Review of the First Wireline In Situ Stress Test in Scientific Ocean Drilling

Abstract

Scientific ocean drilling’s first in situ stress measurement was made at Site C0009A during Integrated Ocean Drilling Program (IODP) Expedition 319 as part of Nankai Trough Seismogenic Zone Experiment (NanTroSEIZE) Stage 2. The Modular Formation Dynamics Tester (MDT, Schlumberger)wireline logging tool was deployed in riser Hole C0009A to measure in situ formation pore pressure, formation permeability (often reported as mobility=permeability/viscosity), and the least principal stress (S3) at several isolated depths (Saffer et al., 2009; Expedition 319 Scientists, 2010). The importance of in situ stress measurements is not only for scientific interests in active tectonic drilling, but also for geomechanical and well bore stability analyses. Certain in situ tools were not previously available for scientific ocean drilling due to the borehole diameter and open hole limits of riserless drilling. The riser-capable drillship, D/V Chikyu,now in service for IODP expeditions, allows all of the techniques available to estimate the magnitudes and orientations of 3-D stresses to be used. These techniques include downhole density logging for vertical stress, breakout and caliper log analyses for maximum horizontal stress, core-based anelastic strain recovery (ASR, used in the NanTroSEIZE expeditions in 2007–2008), and leak-off test (Lin et al., 2008) and minifrac/hydraulic fracturing (NanTroSEIZE Expedition319 in 2009). In this report, the whole operational planning process related to in situ measurements is reviewed, and lessons learned from Expedition 319 are summarized for efficient planning and testing in the future

In situ stress and pore pressure in the Kumano Forearc Basin, offshore SW Honshu from downhole measurements during riser drilling

“…[9] Drilling at Site C0009 marked the first riserbased operation in IODP history. This allowed several measurements and operations new to scientific ocean drilling, including the collection of returned drill cuttings and mud gases, the use of weighted mud, leak-off testing (LOT), and in situ downhole measurements with the Schlumberger's Modular Formation Dynamics Tester (MDT) wireline tool [Expedition 319 Scientists, 2010a, 2010bSaffer et al, 2010;Moe et al, 2012]. One of the primary objectives of drilling at this site was to document the stress state and pore pressure below the forearc basin and above the locked and seismogenic plate boundary.…”

“…Geosystems G 3 G method for each of these tests (for details of the operations for each test, see Moe et al [2012], Saffer et al [2010], and Expedition 319 Scientists [2010a]). [12] In the SP tests, a probe was pushed against the borehole wall and isolated from the borehole by a sealing ring, and 0.5-1.0 Â 10 À5 m 3 of fluid was extracted from the formation at a rate of 3.0-8.0 Â 10 À5 m 3 min À1 to reduce the pressure.…”

“…For most of our tests, the drawdown and recovery were repeated at least once ( Figure 5). The fluid pressure is monitored during the test to estimate the fluid mobility (equal to permeability/viscosity) and the in situ formation pore pressure [e.g., Saffer et al, 2010;Moe et al, 2012] ( Figure 5). For a vertical borehole, the semispherical flow controlling the SP test response primarily samples horizontal formation permeability [Stewart & Wittman, 1979].…”

Determination of stress state in deep subsea formation by combination of hydraulic fracturing in situ test and core analysis: A case study in the IODP Expedition 319

“…The riser system provided easy and safe access for such a big tool to enter and exit a borehole at the seafloor far below the drill floor. Moe et al [2012] reported the operational planning process related to the in situ tests carried out in Hole C0009A.…”

“…Contrary to this, the stress state in rocks allows us to immediately infer crustal dynamics involving the rocks, which is typically represented as Anderson's classification of faulting, i.e., normal, thrust, and strike-slip faulting, and the stress is necessary for safe construction and maintenance of underground man-made structures, including boreholes. The first in situ stress measurement of scientific ocean drilling was carried out at Site C0009 during the Integrated Ocean Drilling Program (IODP) Expedition 319 as part of Nankai Trough Seismogenic Zone Experiment (NanTroSEIZE) Stage 2 [Saffer et al, 2010;Moe et al, 2012]. A new borehole, Hole C0009A, was drilled to 1603.7 mbsf (meters below seafloor) from the seafloor at a water depth of 2054 m, and hydraulic fracturing tests for stress measurement were performed using the latest wireline logging tool.…”