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AAPG Pacific Section Convention, 2020 Vision: Producing the Future:

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Subsurface Fracture and Stress Determination using In-situ Full Azimuth Seismic Previous HitdataNext Hit and Orthorhombic Imaging and Previous HitInversionNext Hit

Abstract

High density full azimuth seismic Previous HitdataNext Hit acquisition may record Previous HitdataNext Hit revealing information about sub-surface fracture and stress orientation and intensity. This information is useful for prospecting and developing unconventional and tight reservoirs. Current Previous HitmethodsNext Hit to recover reliable fracture information based on azimuth sectoring with offset vector tiling (OVT) are often not sampled sufficiently in azimuth to accurately recover in-situ stresses and fractures. Furthermore, gathers constructed from offset vector tile Previous HitmethodsNext Hit organize Previous HitdataNext Hit based on surface acquisition parameters. These solutions are often compromised by complex overburdens and complex geology. Orthorhombic velocity Previous HitmodelingNext Hit, imaging, and Previous HitinversionNext Hit for fracture properties provide key alternative technologies to recover natural fractures. However, the determination of orthorhombic parameters is challenging and requires special Previous HitmethodsNext Hit to obtain in-situ azimuths with rich sampling. Additionally, proper orthorhombic imaging and Previous HitinversionNext Hit in the depth migration domains require interval parameters rather than simple effective parameters. In this paper, we present methodology where the entire process of orthorhombic imaging and characterization is carried out in the Local Angle Domain (LAD), a domain that describes subsurface image points by two polar angle systems that capture full azimuth reflectivity and full azimuth directivity. The Previous HitdataNext Hit parameters are measured in-situ over all reflection angles and azimuths making Previous HitdataNext Hit more relevant for further analysis (e.g. Previous HitinversionNext Hit for fracture properties). In order to build an orthorhombic velocity model for imaging and fracture characterization, other workflow steps are essential to ensuring a more stable and reliable outcome. These processes include shallow velocity Previous HitmodelingNext Hit, surface noise attenuation and Previous HitdataNext Hit regularization for low fold acquisitions. This paper will also cover the orthorhombic imaging and Previous HitinversionTop procedures, and other processing steps that are pre-requisite for a successful outcome. Advantages of imaging and characterization in the local angle domain are central to the workflow and will also be covered in this paper. The resulting fracture/stress maps are consistent with the geology of the area and observations in the well.