Presenter
Mauro Viandante from SLB
Co-authors
JM denichou, SLB; Redha Al-Lawati, SLB; J. Adam Donald, SLB;Maren Eide, SLB;Eman Samir, SLB; Fahad Al Qassabi, Marwa Al Shaqsi, Adil Al Hamadani, Khalil Al Arafati, Clive Johnson, Khalil Hassan, Jalal Al Shukaili, Oxy Oman
Abstract
Well placement and real time evaluation of high angle and horizontal wells is a well-established workflow that effectively ensures a consistent distance to the caprock and/or hydrocarbon water contact and delineates sublayers within the reservoir. Contrasts in deep resistivity measurements are interpreted as changes to hydrocarbon saturation or formation composition. Wellbore images show layer boundaries and fractures that intersect the wellbore. Sonic imaging in the same environment provides information about contrasts in acoustic impedance associated with geological features such as structural and stratigraphic boundaries, and the presence of natural fractures/faults. This paper will discuss how combining all three measurements provide rich insights to reservoir characterization in a horizontal well drilled through a carbonate reservoir. The integration of 3D resistivity mapping, with 3D sonic imaging provides unprecedented reservoir insight. 3D Resistivity Mapping is challenged by resistivity response to formation boundaries or fluid changes within the volume of investigated rock. Incorporating the 3D sonic imaging with its sensitivity to lithological or stratigraphic boundaries and natural fractures provides a more comprehensive interpretation. There are three major discoveries within this case. First, there is consistency of dip, azimuth, and distance to the cap rock for both the acoustic and resistivity measurements, however there is also a clear reflection from the bottom of the reservoir layer. The free water level within the layer can be determined as the resistivity profile defines the saturation changes until the bottom boundary, and potentially the oil water contact. Second, correlation can be made between steeply dipping or near vertical acoustic reflectors running parallel to the well trajectory and the lateral changes in the resistivity profile on either side of the wellbore. This is interpreted as saturation changes laterally caused by the presence of near vertical fractures or compartmentalized flow units due to the nature of the rock or existing baffles/barriers within faulted blocks. The third observation is the layering and heterogeneity within the cap rock which includes subtle resistivity contrasts and variable sub-horizontal reflectors that vary with strike and dip. The convention of the caprock of being a homogenous unit, is confronted by the measurements highlighting its heterogenous and anisotropic nature.
Biography
Mauro Viandante is the GeoSteering and Reservoir Mapping Domain Champion for SLB HQ. Mauro has 16 years of experience in drilling, logging and geosteering in the North Sea, Europe, Australasia and Middle East. He has been involved in field-test development of both hardware and software of new LWD technologies (GeoSphere, PeriScopeHD, GeoSphereHD, IriSphere and GeoSphere 360) and has authored several papers on geosteering technique and LWD technology. Mauro holds an MS degree in geology and a PhD degree in structural geology from the University of Chieti-Pescara.