Analytical Approach to Determine the Degree of Interference Between Multi-Fractured Horizontal Wells

Abstract

Abstract Economic development of unconventional reservoirs heavily relies on hydraulic fracturing of horizontal wells in multi-well pads. The application of this technology poses the challenge of determining optimum well spacing. For this reason, well interference analyses have recently gained increased attention in the industry. The objective of this study is to present an analytical well interference model that is aimed to diagnose interwell communication between multistage-fractured horizontal wells (MFHW) in liquid-rich shales in a dual-well system via fracture overlapping or fracture "hits". The mathematical model is based on the application of the trilinear flow model to two parallel MFHW connected through the inner fracture tips. This situation is represented mathematically using a semi-permeable boundary condition. This condition features a constant α, called the well interference coefficient, which allows history-matching the analytical model with pressure-transient data. Once α is obtained, the degree of well interference is measured using the parameter δw, representative of the fraction of the fractures in comunication. Pressure-transient data is generated numerically for four different dual-MFHW systems with 5, 10, 20 and 50 fractured stages. Fractures half-length also changes for each case study. Petrophysical data from the Lower Eagle Ford shale found in the literature is used to build the reservoir model. It is shown that the analytical well interference model accurately captures the characteristic pressure-transient behavior of interwell communication due to fracture hits byhistory-matching α with well data for each system. Various degrees of interference are allowed in all system so that a relationship between α and δw is established for each case. Therefore, the degrees of interference δw systematically computed by history-matching α with numerical pressure-transient data from a parent multi-stage fractured system may be extended tomulti-well systemsregardless of thenumber of fractures, so long as both wells have similar characteristics, including reservoir properties and fracture half-length.