Marcellus shale gas Bradford Co Pennsylvania: production history and declines

  • From a standing start in 2009, natural gas production from the Marcellus Shale in Bradford County Pennsylvania (PA) now exceeds 2.2 billion cubic feet (bcf) per day from 728 wells (to end June 2013).
  • To put this in perspective, the UK consumes about 8 bcf per day and so 4 Bradford counties (about 3000 wells) could make the UK self- sufficient.
  • The catches are that Bradford County is a production sweet spot – you have to find the sweet spots before you can produce them. And to keep production going, over a hundred new wells need to be drilled every year.
  • 6 charts below the fold show the production history, average well productivity and decline rates from Bradford County.

Figure 1  This chart shows the production stack for 728 Marcellus shale gas wells, Bradford Co. PA. XL would only let me plot about 150 data series and so the wells are aggregated into production from groups of 5 wells. The black line shows the number of producing wells, right hand scale. Data from the Pennsylvania Department of Environmental Protection (DOEP). Click on all charts to get a larger version that will open in a new browser window.

My next post will be titled “Shale gas myths and realities” and for that post I want to try and quantify the type of impact that shale developments may have on communities in Europe. One of the most important factors is the number of wells and that depends upon well productivity. I went looking for data and came across the Pennsylvania Department of Environmental Protection shale gas portal. This provides production figures for all counties aggregated into 6 month periods.

A lot of drilling activity in Bradford County suggested this was a production sweet spot and I began looking at this data simply to get a handle on typical flow rates. I ended up looking at over 700 wells which was a more extensive analysis than I originally planned.

Decline rates

All geologists and petroleum engineers already know that shale plays experience high decline rates compared with conventional reservoirs. This is important for the man on street to know because once you go down the shale route, you are making a commitment to drill more and more wells every year to keep production going. Decline is a phenomenon that affects all wells (conventional and unconventional) which results in production falling from one year to the next.

Figure 2 Chart showing only wells that were brought into production Jul-Dec 2009 and Jan-Jun 2010. Decline rates shown as % numbers relative to the production from the preceding year. Decline for 2013 is calculated by doubling the production recorded Jan to Jun and comparing that with 2012 (applies also to Figures 3 and 4). This will tend to underestimate the decline. On all charts, years are shown in duplicate, the first date is for Jan to Jun and the second for Jul to Dec.  That is apart from 2009/2 and 2010/1 where the data are aggregated for 12 months by DOEP (not a calendar year).

Figure 2 shows only the wells drilled and brought on stream Jul-Dec 2009 and Jan-Jun 2010. All the wells drilled subsequently (Figure 1) are not plotted and this provides a clear picture of  the aggregate decline in these first shale wells drilled in Bradford County. Production in 2011 fell by 42% compared with the year before. Year 2 (2012) showed a 31% decline and year 3 (the first 6 months of 2013) a 22% decline. Had the drillers not kept drilling, production in Bradford County would now be 100 million cubic feet per day as opposed to the 2.2 billion cubic feet per day at end June 2013. The intensity of drilling required to deliver the 2.2 billion cubic feet per day “miracle” is shown in Figure 7. And so it is clear, to keep shale production going you have to drill – lots and lots of wells.

Figure 3 is the equivalent to Figure 2 but for wells brought on line in the second half of 2010. Note how for a similar number of wells the aggregate production is 350 million cubic feet per day compared with 250 million cubic feet per day shown in Figure 2. And the first year decline is a lower 33%. The industry seems to be learning.

Figure 4 Same as previous two figures but for wells brought on stream the first half of 2011. Productivity once again is up and first year declines are down (see Figure 6.)

Figure 5 Summing the data shown in Figures 2, 3 and 4 produces this broad picture of how shale gas production has evolved in Bradford county, showing wells brought on stream up to June 2011. The picture is easily completed but it is time consuming to compile the data.

Figure 6 This figure shows the average well performance and how it has evolved over a very short 18 month period. The improved performance with time in Bradford County is quite clear.

Figure 6 is important because it shows how the industry is learning to drill shale better. There can be two factors at work here. The first is identifying better areas to drill. The second is drilling wells better, i.e. better well engineering to enhance flow rates. Watching how this type of chart evolves with time will provide clear indications to the long-term future of the shale gas industry. Once new wells begin to under perform old wells production will be overwhelmed by declines.

Figure 7 The drilling history in Bradford County PA.

In conclusion, European citizens seem concerned about every aspect of the infrastructure required to deliver the energy that is essential to provide them with the basic needs such as food, heat, light, work, health care, welfare, pensions, etc. It is time for citizens to start weighing the risks of infrastructure against the benefits of having heat and light, 24 hours per day, 7 days a week (24/7). There is no easy way, only difficult choices to be made. My next post will try to layout the risks and benefits of shale gas development in Europe.

Note that this technical post contains information that is of value to energy companies, investment companies, investors, policy makers, politicians, environmental regulators etc. It has taken over 2 days to compile this data. In future I will be providing a number of these data driven posts (1 to 2 per month) and feel that it is only fair that those who benefit pay for the service. Otherwise the service will inevitably end.

I have added a donate button to Energy Matters. If you are in a profession and feel you have benefited from this post in any way then please “donate” £10 (or more). More on Energising Energy Matters to follow.

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10 Responses to Marcellus shale gas Bradford Co Pennsylvania: production history and declines

  1. Roger Andrews says:

    According to DOE EIA total production from the Marcellus is now 12 bcf/day, 50% more than UK gas demand, and decline rates are apparently not as steep as anticipated. And all this from an area less than half the size of the UK.

    However, the US has two major advantages when it comes to gas production that are unrelated to infrastructure. First, not all oil and gas rights in the US are owned by the government, as they are in the UK. The US shale gas boom has in fact taken place entirely on land not owned by the feds. Had all US gas rights been owned by the feds it probably never would have happened:

    Second, the US doesn’t have a Climate Change Act. It’s going to be difficult to sell the UK government on burning more gas after it’s passed a law to cut back on the use of fossil fuels, and the same goes for the EU with its Climate and Energy Package.

    • Euan Mearns says:

      Roger, thanks for this insightful comment. I am relieved to hear that the whole of PA is producing 12 bcf / day meaning that Bradford County is about 20% – sounds about right. Managing so much data, I’m always worried about making a mistake, and 2.2 bcf sounded an awful lot of gas.

      The fact that land owners benefit from selling leases will clearly drive things forward in the USA. But that can be a double edged sword.

      The point you make about Climate Change Act (that should be repealed ASAP) is spot on. It is down right hypocrisy to preach environmental care, CO2 abatement and to pursue shale gas. The government’s get out of jail free card is carbon capture and storage (CCS). Going that route soon everyone will be working for the energy industries as energy return on invested converges on unity (ERoEI converges on 1).

      The whole CO2 intensity vocabulary is double speak (George Orwell 1984). The rate at which one country produces CO2 has absolutely zero impact on the long term future of Earth’s climate – whether you believe in global warming or not. The important variable is the ultimate amount of CO2 produced, therefore, beginning to attack the next layer of the resource pyramid, i.e. shale, is absolutely the last thing you should be doing – if you proclaim concern about global warming. Unless of course you propose CCS at the same time.

  2. Roger Andrews says:

    Euan: You don’t actually have to repeal the Climate Change Act. You can simply change the emissions reduction target, which the Act allows you to do if “scientific knowledge” changes. The relevant wording is:

    “It is the duty of the Secretary of State to ensure that the net UK carbon account for the year 2050 is at least 80% lower than the 1990 baseline.

    “The Secretary of State may by order …… amend (this) percentage … if it appears to the Secretary of State that there have been significant developments in …… scientific knowledge about climate change …”

    I don’t know whether thousands of poor people freezing in the dark would qualify as a development in scientific knowledge, but the fact that the earth hasn’t warmed for ~15 years while CO2-forced models say it should have probably would.

  3. Greg vP says:

    I’m not used to working with cubic feet as an energy unit, so I didn’t have a feel for the return on effort. Sure, there are 700 or 800 wells, but is that ‘normal’ or not? You imply it’s a large effort for low return, Euan, but I wanted to know more precisely.

    So I converted to oil equivalents. Eyeballing your charts, the 80 wells in place in early 2010 are now producing approximately 95 million cu. ft per day. Using the conversions 1 cu. ft. NG provides 1.0 MJ (net), and 1 kg of light oil provides 42 MJ and is a volume of 1/111th of a barrel, the wells are producing a bit over 2 barrels of oil equivalent per day each. (My conversion figures might be out a bit, but I don’t think that changes the interpretation: this is not a big flow of energy.)

    OK. Now I see why you talk about the drilling and fracking effort so much.

    On European shale: Europe has always been comfortable importing the bulk of its energy, and has a more effective ‘green’ voice than does the USA.

    The way democracies work is that hard decisions are put off, and put off, until people are screaming–and then the most expedient ‘fix’ is chosen. For Europe, that’s importing LNG.

    • Roger Andrews says:

      I get a little over 200 barrels of oil equivalent/well/day for 80 wells producing 95 million cu ft/day, but maybe I did the calculations wrong.

      • Euan Mearns says:

        Greg and Roger, the BP stat review has a page of useful conversion factors. 1 billion ft3 of nat gas = 0.19 million barrels oil equivalent (boe). 95 million ft3 / day = 18,000 boe / day for 80 wells = 225 boe / day / well. Roger was on the money. This is a lot for a country gotten used to stripper wells that produce a few barrels/day.

        I also see this “shale promise” as a way of putting off actually dealing with the situation. The plan was to import LNG – but that plan is not going according to plan. I still think the only mid-termsolution (50 years) is nuclear.

  4. Greg vP says:

    That’ll teach me for trying to do the calculations in my head. It’s not big enough for all those zeros. 😉

    200 boe/day is a lot? Not for a three year old well, traditionally. How times change!

  5. Bob Spoley says:

    The horizontal drilling play, regardless of it being in shake, sand, or lime is considered an “unconventional resource play”. That is usually denominated by the fact that the “resource” has very high water saturation, low porosity, and extremely low permeability. The only the “resource” can be accessed is by horizontal drilling (read rock exposure), fracing (read permeability improvement), and de-watering (read relative permability improvement). None of the above changes the porosity or the reserves that are in place. The large number of wells required to be consistently drilled and consistantly increased is a function of horrible decline curves which are afunction of the reserves in place. Like the Queen of Hearts in Alice in Wonderland. You have to run like the devil just to stay in place. This whole process is designed for the fund companies who make their money on fees which are based on activity, not success or failure. It’s just like a gambling casino. The investor is the gambler and the house is the “equity fund”. The house always wins as long as the investor keeps gambling. The gambler keeps gambling as long nas they feel like they are making money, say 2:1 ROI over time. If the gambler starts losing money, he quits and the “equity fund” fails just like a b\gambling casino will if nobody wins enough to justify the time and expenditure. The horrible decline curves on these “resource plays” guarentee the gambler will lose. The only to build a long term successful resource company is to have very low decline curves and a lot of in-place reserves, not fees.As for future energy freedom, I’ll bet on thorium reactors for “in – place energy usage and methane hydrates followed by GTL technology to produce diesel which is followed by TDI tech for efficiency. That will handle the mobile fuel usage, the rest is pie in the sky as far as I am concerned.
    Bob the Cossack

    • Euan Mearns says:

      Bob, can you tell us why Th reactors have not been previously developed – I had a student ask that yesterday and couldn’t give a good answer. And how do you envisage methane hydrates being “produced”?

  6. David Harrison says:

    Euan, if the shale gas displaces coal in the power generation mix then you may not even have to repeal the Climate Change Act. The US is recording significant reductions in CO2 emissions as a result of this switching :

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