Validation of Conductive Fracture Imaging with Cross Well Strain and Permanent Fiber Optic Flow Profiling

Abstract

Abstract The study applies Conductive Fracture Imaging (CFI) on Hydraulic Fracturing Test Site-2 in the Delaware Basin, USA, acquired in 2019. The CFI results are independently delivered and compared with strain data recorded by permanent distributed fiber optic sensor arrays in a vertical data well (the Boxwood 5PH) and two horizontal wells (Boxwood 3H and Boxwood 4H). Boxwood 4H's permanent fiber provides Distributed Acoustic Sensing (DAS) cluster flow and proppant allocation analytics, as well as distributed strain sensing (DSS) for cluster level shut-in pressure build-up tests. The objective of this study is to directly compare CFI results with in-well DAS and DSS fiber optic measurements. CFI utilizes microseismic events as active sources for reflection imaging of the conductive portion of hydraulic fractures, offering high-resolution images of the seismically active zone for precise description of cluster level fluid allocation and conductivity. CFI has been benchmarked successfully against established fiber optic diagnostics, providing insights into conductive fracture geometries, cluster efficiencies, and in-well production flow profiling. Key advantages of CFI include imaging fluid and proppant allocation at the cluster level, offering a four-dimensional view of dynamic transport, estimating fracture height, and providing valuable data on hydraulic and conductive fracture geometries. The study reveals strong correlations between CFI and cross-well strain intensity measured by fiber monitors, as well as good agreement with in-well DAS stimulation fluid allocation. Furthermore, CFI shows clear correlations with cluster level DSS strain changes during the production phase, accurately resolving cluster positions along the wellbore. Cluster level reflectivity values from CFI demonstrate a robust agreement with DSS strain change peak values observed on the same clusters.