Comment: My take was that distance

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My take was that distance

My take was that distance from water wells to the drilling operations was the main factor in the amounts of methane/ethane in the drinking water. Yes, they did admit the reasons were because of poor {gas} well construction. That's good news imho, because 1) now we know what it is, and 2) that sounds fixable to me. (It also sounds like a business oportunity, ie. designing and building better casings, maybe use titanium instead of steel, or something. Could make various versions, thicker casings for wells < 10km from water wells, etc.)

Also, I noticed how they said "drilling operations". This is kind of an "all encompasing" wording if you ask me. I don't think they were trying to be disingenuos though. I think they intended to see if there is correlation with methane, ethane, and propane concentrations. Inside the study was a link to a .PDF file which showed the same graphs, but all together. Looked like methane, ethane, and propane concentrations in the drinking water were all higher the closer the water well was to the gas well. Graphically, to me, that seemed like correlation. Propane was found in only 10 homes, but all were less than 1km from a gas well. Here's the relevant quotes:

This study examined natural gas composition of drinking water
using concentration and isotope data for methane, ethane, propane,
and 4He. Based on the spatial distribution of the hydrocarbons
(Figs. 1 and 2), isotopic signatures for the gases (Figs. 3
and 4), wetness of the gases (Fig. 2 and Figs. S5, S6, and S7), and
observed differences in 4He:CH4 ratios (Fig. 5), we propose that
a subset of homeowners has drinking water contaminated by
drilling operations, likely through poor well construction.

and,

Dissolved methane was detected in the drinking water of 82% of
the houses sampled (115 of 141). Methane concentrations in
drinking water wells of homes <1 km from natural gas wells (59
of 141) were six times higher on average than concentrations for
homes farther away..... Ethane was detected in
40 of 133 homes (30%; 8 fewer homes were sampled for ethane
and propane than for methane). Propane was detected in water
wells in 10 of 133 homes, all approximately <1 km from a shale
gas well.

I don't know what wire-line perforation is from your post, but will look it up. On the oil thing, I saw 2 points of data that appeared to conflict with each other, but I'm no scientist, I probably just didn't understand what the point the author was trying to make. If 12% of oil wells in the Gulf of Mexico were able to sustain their casing pressure from 1 yr after going online, then how does 50-60% of oil wells in the gulf sustain their casing pressure for 15 yrs? I don't get it.

The part I'm refering to here (on pg5) is followed by a statement about the time factor you were seeking:

A comprehensive analysis of ∼15,500 oil and
gas wells (43) showed that 12% of all wells drilled in the outer
continental shelf area of the Gulf of Mexico had sustained casing
pressure within 1 y of drilling, and 50–60% of the wells had it from
15 y onward. For our dataset, there is a weak trend to higher
methane concentrations with increasing age of the gas wells (P =
0.067 for [CH4] vs. time since initial drilling). This result could
mean that the number of drinking water problems may grow with
time or that drilling practices are improving with time; more research is needed before firm conclusions can be drawn.

Also here is a part where they admit more timeline type research is needed:

More extensive predrilling data would also be helpful. Additional
isotopic tools and geochemical tracers are needed to determine
the source and mechanisms of stray gas migration that we
observed. For instance, a public database disclosing yearly gas
compositions (molecular and isotopic δ13C and δ2H for methane
and ethane) from each producing gas well would help identify and
eliminate sources of stray gas (49).

Lastly, they did mention that there are a large number of old wells that are presumed to be out of service, that are unaccounted for because the state doesn't seem to track them. Weird, since when does the STATE not TRACK something? L0L! Here's the part on that:

In 2000, the Pennsylvania DEP estimated that it had records for only 141,000 of 325,000 oil and gas wells drilled historically in the state, leaving the status and location of ∼184,000 abandoned wells unknown (47). However, historical drilling activity is minimal in our study area of northeastern Pennsylvania, making this mechanism unlikely there.

In closing, by reading your reply several times, you seem like someone who probably reads this kind of stuff all the time. I must admit this was very challenging for me to read. Although I am used to reading process specifications and engineering drawings, this acedemic material was a struggle. I think you brought up some valid questions, and your reply challenged me. As a result, I found something that I thought didn't jive (the gulf wells thing). Anyways, thx for the reply. Hopefully I found something relevant to the points you brought up.