Joint 3D Inversion of Direct and Reflected Arrivals from Surface and SWD Seismic Data

A B S T R A C TThe orientation of three-component borehole geophones used for recording during a microseismic monitoring experiment is estimated. The standard technology for deploying multi-component geophones in a deep borehole is wireline-based, in which the azimuthal rotation of the geophone string cannot be controlled. Each receiver can have a different rotation angle that is compensated by the particle motion analysis of the direct P-wave arrivals, picked from a walk-around VSP carried out in the proximity of the well. Knowing the orientation of borehole receivers is critical, as inaccuracies lead to systematic errors in determining the hypocentral coordinates of microseismic events. Additional errors arise from over-simplifications of P-and S-wave velocity Earth models.In this paper, we propose a tomographic approach for improving the orientation estimates of borehole receivers based on hodogram analysis. The initial velocity model built from well logs and upholes is refined by 3D tomographic inversion of walkaround VSP data and some string shots fired in a nearby borehole. Taking into account ray bending, the estimated errors due to local velocity anomalies can be reduced. This makes our estimates of fracture orientation and microseismic hypocentres more reliable when borehole receivers are used in passive seismic surveys.

Section: Discussionmentioning

confidence: 99%

“…The tomographic algorithm is based on minimum‐time ray tracing in blocky irregular grids (Vesnaver 1996; Böhm, Carcione and Vesnaver 1996) and can jointly invert the traveltimes of P‐, S‐ and any type of converted wave (Rossi et al . 2001).…”

Section: D Traveltime Tomographymentioning

confidence: 99%

Borehole receiver orientation using a 3D velocity model

Menanno

Vesnaver

Jervis

2012

“…The joint inversion of surface and borehole data increases the illumination angle at the target and constrains the depth of the interfaces better. Rossi et al . (2001a,b), among others, validated such an integration for active seismic methods.…”

Section: Joint 3d Tomographymentioning

confidence: 99%

“…The joint 3D tomography of surface and well data is a proven technology in seismic exploration (Rossi,Vesnaver and Petersen 2001a; Rossi et al . 2001b, among others) but it is still in a pioneering phase when involving both active and passive seismic data (Battaglia et al .…”

Section: Introductionmentioning

confidence: 99%

Joint 3D processing of active and passive seismic data

Vesnaver

Lovisa

Böhm

2010

A B S T R A C TPassive seismic provides additional illumination sources in producing reservoirs, improving the Earth's imaging obtained by standard 3D seismic surveys. The joint tomographic inversion of surface and borehole data, both active and passive, even allows the delineation of thin reservoirs that cannot be resolved by reflection tomography. As an application example, we present a feasibility study for a real case of CO 2 geological storage, showing that this operation may benefit both environment and reservoir monitoring.The origin time of micro-earthquakes due to production operations is critical for merging active and passive data. We show here that the Wadati's method is not accurate for borehole data in a layered earth model, when the ratio between P and S velocities is not constant, as occurs in most hydrocarbon reservoirs. This drawback can be solved by deploying a few receivers at the surface close to the well.

“…The inversion of the refracted traveltimes is based on an iterative procedure in which both the velocity field and the geometry of the refractors are inverted; the estimate of the refractor geometry is based on the minimum dispersion of the refracted points (e.g. Rossi et al . 2001).…”

Section: Traveltimes Tomographic Inversion and The Calculation Of Tommentioning

confidence: 99%

Tomographic joint inversion of first arrivals in a real case fromSaudi Arabia

Böhm

Accaino

Rossi

et al. 2006

A B S T R A C TA joint inversion of both first and refracted arrivals is applied on a seismic line, acquired onshore, in order to obtain a well-resolved velocity field for the computation of static corrections. The use of different arrivals in the inversion involves exploiting the information derived from the different raypaths associated with each wave type, thus enhancing the reliability of the inversion. The data was gathered by Saudi Aramco in an area of the Arabian Peninsula characterized by strong lateral variations, both in topography and shallow velocity, and where therefore a well-defined near-surface velocity field is important. In addition to velocity, the depth distribution of the quality factor Q is computed from the tomographic inversion of the seismic-signal frequency shift. Thus, the Q-factor field is used to perform an inverse Q-data filtering and improve the resolution of the final stacked section.