TI anisotropic model building using borehole sonic logs acquired in heterogeneous formations

Jocker, Jeroen; Ferla, Maurizio; Pampuri, F.; Wielemaker, Erik; Sunaga, Shinichi

doi:10.1190/segam2013-1120.1

Cited by 7 publications

(8 citation statements)

References 6 publications

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“…The industry has tried to overcome this limitation by combining measurements from wells at multiple orientations. Jocker et al (2013) presented a workflow to quantify TI anisotropic parameters on basis of borehole sonic data in heterogeneous formations. This workflow requires the combination of advanced sonic measurements and independent petrophysical logs together with the layering orientations.…”

Section: Sonic-derived Ti Anisotropy As a Guide For Seismic Velocity mentioning

confidence: 99%

“…The final MVA result is a seismic velocity model with an associated degree of uncertainty in the sense that a multitude of models will flatten the gathers equally well. Meanwhile, aside from their conventional use as well calibration, advanced borehole sonic datasets also provide an in-situ measurement of anisotropy via workflows such as discussed in Jocker et al (2013). The CMP gather on the right in Figure 2 demonstrates that a velocity model guided by sonic anisotropy parameters explains the observed reflection moveouts in the seismic gather.…”

Section: Seismic Data Example: Cmp Gather Flatteningmentioning

confidence: 99%

“…The seismic TI anisotropy study was performed in an area that included an offset well at a distance of approximately 10km from the wells whose sonic datasets were previously used for the study described in Jocker et al (2013). The resulting relationships between petrophysical properties and the elastic properties were subsequently used to estimate the expected anisotropy in the offset well, as illustrated in Figure 4.…”

Section: Extension To Offset Wellsmentioning

confidence: 99%

“…Meanwhile, borehole sonic data provide in-situ measurements of the velocity while combining sonic datasets from different wells allows for a full description of TI anisotropy with depth (Horne et al, 2013, Jocker et al, 2013. While this information is potentially of use as a constraint on the seismic velocity model, the consistency between sonic-based anisotropy curves and the surface seismic data remains, as of yet, unclear.…”

Section: Introductionmentioning

confidence: 99%

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Sonic-derived TI anisotropy as a guide for seismic velocity model building

Ferla¹,

Pampuri²,

Corciulo³

et al. 2015

SEG Technical Program Expanded Abstracts 2015

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While accurate velocity models are critical for seismic images representative of the subsurface, the process of determining the correct velocity model is non-unique. Seismic images may therefore come with significant uncertainty, especially in fields with complex structure in combination with a complex velocity field. In turn, this uncertainty leads to wells missing their targets as well as increased drilling risks. Borehole sonic-derived anisotropy magnitudes may provide constraints to the seismic velocity model, but the applicability of sonic-derived anisotropy to surface seismic data is unclear. In this paper, the consistency between a sonic-derived anisotropic velocity model and surface seismic data is analyzed by comparing NMO corrections on basis of a seismic-only model versus a seismic model guided by sonic-derived anisotropy. For the complex seismic dataset presented in the examples it is observed how (unlike the sonic-guided model) the seismic-only model is not able to flatten the gathers at far offsets. The process of deriving TI parameters from borehole sonic data is relatively efficient (compared to the seismic equivalent), and their use as a guide during the construction of the seismic velocity model results in subsurface images that can be established with greater confidence.

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Section: Sonic-derived Ti Anisotropy As a Guide For Seismic Velocity mentioning

confidence: 99%

Section: Seismic Data Example: Cmp Gather Flatteningmentioning

confidence: 99%

Section: Extension To Offset Wellsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Sonic-derived TI anisotropy as a guide for seismic velocity model building

Ferla¹,

Pampuri²,

Corciulo³

et al. 2015

SEG Technical Program Expanded Abstracts 2015

Self Cite

View full text Add to dashboard Cite

show abstract

“…Two reasons can be found for this lack of wide acceptance: 1) the measurement of all five TI elastic parameters from sonic was not available at the time, 2) no independent validation of the rather complex Lekhnitskii-Amadei solution existed. Recently, the introduction of modern multipole sonic tool (Pistre et al, 2005) led to the development of several new techniques to invert for the full set of TI elastic properties (Jocker et al, 2013). Gaede et al (2012) also showed by comparing the LekhnitskiiAmadei solution to finite-element simulations that the solution is generally correct for any symmetry class including isotropy.…”

Section: Introductionmentioning

confidence: 98%

Anisotropic Wellbore Stability Model and Its Application for Drilling through Challenging Shale Gas Wells

et al. 2014

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This paper describes a new anisotropic wellbore stability model and its application in a challenging shale gas well in China. Wells drilled through laminated rocks like shales -particularly deviated wells such as laterals -are often less stable than comparable wells drilled into non-laminated rocks. This results in significant wellbore instability issues that can elevate drilling operation costs substantially. Traditional wellbore stability analysis considers the formation as a homogeneous isotropic material using isotropic elastic near wellbore stresses together with isotropic borehole failure criteria such as MohrCoulomb. In anisotropic rocks, for example in highly laminated shales and fractured rocks, those models are no longer valid as borehole failure can occur along weak planes.We have developed such an anisotropic wellbore stability model in which the rock anisotropic elastic properties and anisotropic strength characteristic are incorporated. Near borehole induced stress is computed by Lekhnitskii-Amadei solution to account formation anisotropic behavior, and wellbore shear failure mechanism is modeled by a modified Plane-of-Weakness model, where the classical Plane-ofWeakness failure criterion is adopted to identify the onset of rock sliding along a weak plane; and the active shearing effect is adopted to judge whether the onset sliding at the borehole wall will develop and cause borehole instability. Arbitrary bedding/fracture orientations as well as arbitrary wellbore trajectory and in situ stress orientation is considered by this model. The model can predict the extent of failure region around the wellbore and then provide mud weight window for safe and effective drilling.Additionally, this approach was programmed into a software system and applied to a field case study -wellbore stability analysis and mud weight computation for a slightly deviated pilot well drilling through laminated shales. The laminated shales are penetrated by high-angle natural fractures. Our modeling results shows the design borehole can be drilled without encounting severe instability issue, however, borehole damage due to either weak planes (laminated layers and fractures) sliding or rock matrix shear failure were predicted. The borehole damage mode and severity is largely dependent on borehole relative orientation with the weak planes, and the directions and magnitudes of the in situ three principal stresses. The computed borehole damage was compared to borehole image (FMI) and caliper measurement and gave a good agreement. Subsequently this model was applied to predict the mud weight window for an Extended Reach Drilling (ERD) in the field and provide wellbore stability analysis to drill high-deviated wells in the area. We showed that this developed model is effective to provide insight in understanding borehole failure mechanisms, and provide more reasonable mud weight window which can be used to effectively mitigate wellbore instabilities in anisotropic condition.

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