Description
Diagnostic fracture injection testing (DFIT) is an efficient way to derive in-situ information in many rock types. With this technique, a modestly-sized hydraulic fracture is created in the target interval (pay zone or bounding interval) and pressure fall-off during the shut in period is analyzed to identify fracture closure and an after-closure radial flow period. Injection rate and volume are tailored for interval thickness and leak-off characteristics.
Identification of fracture closure is based on derivative-based diagnostic plots and provides information on rock stress. As well, non-ideal fracture propagation (e.g., fracture height growth, fissure opening, multiple fracture closures) can be identified and evaluated.
After-closure analysis is used to derive rock transmissibility (kh/u) and initial reservoir pressure (pi.) Radial flow is identified and evaluated by type curves and specialty plots.
The parameters derived in DFIT analysis are used to model fracture propagation and optimize fracture design for the indicated reservoir characteristics, and to provide information for reservoir modeling and production forecasting.
The presenter will describe the basic theory and practice of DFIT analysis. Field examples from various locations, completion types and reservoir systems, including shale gas, unconsolidated sand and low-pressure reservoirs, will be reviewed to describe test design and interpretation.