Just a little website i just found. Who ever did it seems to be passionate about the problem. Links tons of SPE documents.
“A video showing a sample of Castlegate sandstone (outer cylinder) and Portland G cement (core). The blue regions at the interface between these materials represent pores/voids. High interface porosity indicates poor cement bonding, and if the pores are connected into leakage paths – they can cause loss of well integrity. The three dimensional (3D) reconstruction is based on X-ray micro computed tomography (micro-CT) data, and the video is made using the Avizo software.”
Contamination of aquifers by overpressurizing the annulus of oil and gas wells
WATER RESOURCES RESEARCH: POTENTIAL OF HYDRAULICALLY INDUCED FRACTURES TO COMMUNICATE WITH EXISTING WELLBORES
“The probability that new hydraulically fractured wells drilled within the area of New York underlain by the Marcellus Shale will intersect an existing wellbore is calculated using a statistical model, which incorporates: the depth of a new fracturing well, the vertical growth of induced fractures, and the depths and locations of existing nearby wells. The model first calculates the probability of encountering an existing well in plan view and combines this with the probability of an existing well-being at sufficient depth to intersect the fractured region. Average probability estimates for the entire region of New York underlain by the Marcellus Shale range from 0.00% to 3.45% based upon the input parameters used. The largest contributing parameter on the probability value calculated is the nearby density of wells meaning that due diligence by oil and gas companies during construction in identifying all nearby wells will have the greatest effect in reducing the probability of interwellbore communication.”
“Abandoned wells provide pathways for methane gas to seep to the surface, where it can, under the right settings, trigger explosions. Active drilling near unplugged abandoned wells is dangerous, too.”
Map of Pennsylvania’s known abandoned wells:
Linked documents from PADEP: