Imbibition and Water Blockage in Unconventional Reservoirs: Well Management Implications During Flowback and Early Production

Abstract

Driven by field logistics in an unconventional setting, a well may undergo weeks to months of shut-in following hydraulicfracture stimulation. In unconventional reservoirs, field experiences indicate that such shut-in episodes may improve well productivity significantly while reducing water production. Multiphase flow mechanisms were found to explain this behavior. Aided by laboratory relative-permeability, capillary pressure data, and their dependency to stress in a shale-gas reservoir, the flow-simulation model was able to reproduce the suspected water blocking behavior. Results demonstrate that a well resting period improves early productivity while reducing water production. The results also indicate that minimizing water invasion in the formation is crucial to avoid significant water blockage.

Investigation of multiphase fluid imbibition in shale through synchrotron‐based dynamic micro‐CT imaging

“…Wettability is a key property in multiphase fluid flow in microfractures and shale matrix. It is commonly assumed that clay minerals and other mineral grains are more water wet and organic matter more oil wet [e.g., Bertoncello et al, 2014]. Is this a solid assumption for shale?…”

Simulation of the Impact of Fracturing Fluid Induced Formation Damage in Shale Gas Reservoirs

“…The hybrid approach can be used to simulate matrix-fracture exchange even for a multiphase flow case independently from fracture spacing (Case 1 and Case 2). It has to be mentioned that our simulation results from daily water and daily gas production have been compared with data from Marcellus shale gas wells at early time (e.g., see Cheng 2012;Clarkson and Williams-Kovacs 2012). Hereafter, the simulation results from daily water and gas rate are presented in log-log scale to compare them to data from Marcellus Field (Cheng 2012).…”

“…Li et al (2012) used an analytical model to study fracture-face matrix damage in shale gas reservoirs. Cheng (2012) investigated the formation-damage effect with a numerical model. Agrawal and Sharma (2013) used a 3D numerical simulator to study the gravity effect.…”

Estimating reliable gas rate with transient-temperature modeling for interpreting early-time cleanup data during transient testing

“…The problem compounds when the shale gas reservoirs with nanodarcy permeability are considered. For instance, the study of Bertoncello et al (2014) explored the causes of water blockage by incorporating laboratory-derived relative-permeability and capillary-pressure curves into numerical flow simulations while matching well performance. One of the lessons learned is that the flowback should occur as early as possible, followed by a well shut-in period.…”