Study Investigates Mechanisms for Damage vs. Uplift in Different Basins

Abstract

_ This article, written by JPT Technology Editor Chris Carpenter, contains highlights of paper IPTC 22194, “Modeling Frac Hits: Mechanisms For Damage vs. Uplift,” by Garrett Fowler, SPE, Dave Ratcliff, SPE, and Mark McClure, SPE, ResFrac. The paper has not been peer reviewed. Copyright 2022 International Petroleum Technology Conference. Reproduced by permission. _ Parent/child interactions pose a critical challenge for oil and gas shale producers. The industry has progressed significantly in its understanding of causes and mitigation. However, important uncertainties remain. Fracture-driven interactions, or “frac hits,” exhibit varied behaviors in different basins. The authors of the complete paper examine and contrast a case study in the Bakken in which production uplift occurs with observations of production loss in a case study in Oklahoma. Introduction Publicly available data on frac hits across the Bakken, Eagle Ford, Haynesville, Woodford, and Niobrara show that, in the Bakken and Haynesville, greater than half the documented frac hits resulted in production uplift in the hit well (parent well). Conversely, in the Woodford and Niobrara, more than half of the frac hits resulted in a negative effect on the parent well. In the Eagle Ford, multiple interactions result in a negative effect on the parent well. Several studies in the Woodford examined the formation of “gummy bears” in the parent well post-frac hit. This is a colloquial term for a semisolid mixture containing hydrocarbons, sand, iron, fine particles from clay, and, sometimes, amounts of friction reducer. These gummy bears clog or reduce the conductivity of the fracture network downhole in the wells that are hit, reducing the productivity of the well. While other basins have provided evidence of the phenomenon, evidence of gummy bears is absent from many shale basins, particularly those showing production uplift after frac hits. Methodology The authors investigate potential mechanisms for production uplift and damage in a fully coupled hydraulic fracture and reservoir simulator. The model captures poroelastic stress response from depletion, multiwell fracture interaction, asymmetric fracture growth, multiphase flow in hydraulic fractures as they are reopened during a frac hit, and proppant remobilization. Numerical models force a self-consistent representation of physics. Every model output is a necessary consequence of a model input.