Decoding Positives or Negatives of Fracture-Hits: A Geomechanical Investigation of Fracture-Hits and Its Implications for Well Productivity and Integrity
With the goal of extracting the maximum possible recovery from
unconventional reservoirs, operators try to place their wells as close as
possible. With such well spacing pattern, hydraulic fracture hits among the
horizontal wellbores have become norm. The study presented here aims at
studying the cause and effect of such fracture hits on wellbore productivity
and integrity by numerical simulation and finite element analysis.
Fracture hits have been reported in almost all the unconventional
reservoir basins across North America. In some wells, their impact on
production is claimed to be positive whereas in others it is claimed to be
negative. To further investigate the impact of any fracture hit, advanced
modeling workflows were applied to several case studies. The workflows include
complex fracture simulation model, coupled numerical reservoir simulation, and
finite element geomechanical modeling to evaluate rock deformation due to
hydraulic fracturing, the impact on wellbore and casing integrity, deformation
of the casing, near-wellbore proppant dislodgement, and the effect of time and
distance from the offset wells.
From the study, it is proven that the impact due to a fracture hit on a
well is not only dependent on the geomechanical stress alteration arising from
stimulation in the offset well and its production, but is also determined by
the degree of fluid and proppant dislodged in the near-wellbore area. The
offset-well hydraulic fracture propagation, pressures, and fluid and proppant
transport are also critical in deciding the future productivity after a
fracture hit. A case study demonstrates that the production of the considered
parent wellbore can deteriorate by 17% in 1 year when a fracture hit is
negatively impacting productivity.
The modeling approach allows operators to improve their strategy of pad
development and look at the impacts of fracture hits more closely. Well spacing
decisions are streamlined better following the recommendations from this study.
Whereas closing-up the well spacing to extract the last drop of oil and gas is
important in a pad development mode, the treatment designs must be modified as
required to negate the effects of fracture hits. The study allows operators to
realize the true benefit of optimizing treatments at the multi-well level for
developing an engineered pad development strategy.