Proposed Refracturing Methodology in the Haynesville Shale
During the downturn in the oil and gas industry, many operators have
chosen to refracture their previously underperforming wells to boost economics
with lower investment compared to drilling new wells. More than 100 horizontal
wells have been refractured using chemical diverters across multiple basins in
North America since the second half of 2013. Many papers have been published
discussing these case studies. However, the refracturing results have been
inconsistent. One of the biggest challenges of refracturing with chemical
diverters is not knowing what is happening downhole. To better understand this,
more refracture modeling should be performed to reliably predict production
results before spending the upfront capital for a refracturing treatment.
A proposed refracture numerical simulation methodology was employed to
take into account the historical production depletion using calculated pressure
and stress measurements along the lateral and in the reservoir. The altered
stress fields resulting from reservoir depletion are calculated through a
comprehensive workflow coupling simulated 3D reservoir pressure with a
geomechanical finite-element model described in a previous published paper.
After the stress and pressure are updated, the new approach outlined in this
paper is validated by production history matching real data from a previously
refractured well in the Haynesville basin to provide more confidence in the end
Refracture modeling still poses a major challenge for engineers because
of the reservoir complexity and uncertainty downhole while refracturing.
However, this proposed refracturing approach provides a basic guideline on how
to model refracturing treatments in a numerical simulator with the help of
altered stress fields caused by reservoir depletion. This can be used to better
understand why previously refractured wells perform the way they do and to
better predict the performance of future refractured wells.