LTO – Page 18 – Peak Oil Barrel

Oil Field Models, Decline Rates and Convolution

06/25/201411/14/2019 D Coyne 188 Comments

This post is by Dennis Coyne

The eventual peak and decline of light tight oil (LTO) output in the Bakken/ Three Forks play of North Dakota and Montana and the Eagle Ford play of Texas are topics of much conversation at the Peak Oil Barrel and elsewhere.

The decline rates of individual wells are very steep, especially early in the life of the well (as much as 75% in the first year for the average Eagle Ford well), though the decline rates become lower over time and eventually stabilize at around 6 to 7% per year in the Bakken.

What is not obvious is that for the entire field (or play), the decline rates are not as steep as the decline rate for individual wells. I will present a couple of simple model to illustrate this concept.

Much of the presentation is a review of ideas that I have learned from Rune Likvern and Paul Pukite (aka Webhubbletelescope), though any errors in the analysis are mine.

A key idea underlying the analysis is that of convolution. I will attempt an explanation of the concept which many people find difficult.

At Wikipedia there is a fairly mathematical presentation of the concepts which often confuses people. There are a couple of nice visuals to convey the concept as well see this page.

In the visual below a function f (in blue) is convolved with a function g (in red) to produce a third function (in black) which we could call h where h=f*g and the asterisk represents convolution, just as a + symbol is used to represent addition.

“Convolution of box signal with itself2” by Convolution_of_box_signal_with_itself.gif: Brian Amberg
derivative work: Tinos (talk) – Convolution_of_box_signal_with_itself.gif. Licensed under CC BY-SA 3.0 via Wikimedia Commons.

I think the best way to present convolution is with pictures. Chart A below shows a relationship between oil output (in barrels per month) and months from the first oil output for the average well in an unspecified LTO play.

This relationship is a simple hyperbola of the form q=a/(1+kt), where a and k are constants of 13,000 and 0.25 respectively, t is time in months, and q is oil output.

Chart A is often referred to as a well profile. The values for the constants were chosen to make the well profile fairly similar to an Eagle Ford average well profile. EUR30 is the estimated ultimate recovery from this average well over a 30 year well life.

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Bakken Update, March Production Data

05/14/201405/14/2014 Ron Patterson 130 Comments

The Bakken production data, as well as the All North Dakota production data just came out with their production numbers for March 2014.

Bakken production was up 914,003 bp/d, up 25,091 bp/d from February. All North Dakota production was 977,061 bp/d, up 24,006 bp/d from February. That was a new record for the Bakken but not for all North Dakota. They are still 538 bp/d below their November 2013 numbers.

The surge in the Bakken really started in July 2011 when they doubled number of additional wells per month. Production continued to climb in pretty much a straight line through October 2012. Then bad weather and other problems started to affect production. They are now about 150,000 bp/d below where they would have been had they continued on that trajectory. (Line on chart.)

North Dakota production outside the Bakken declined at about 12% per year until the number of additional wells per month doubled on July 2011. Then it flattened out as some of those new wells were drilled outside the Bakken. But now additional wells outside the Bakken have dropped and so has production. Production outside the Bakken is still down almost three thousand bp/d from the December numbers. So though the Bakken hit a new high in March, total North Dakota production is still below the November numbers.
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North Dakota Bakken/Three Forks Scenarios

02/07/201411/14/2019 D Coyne 226 Comments

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Figure 1

Edit(2/10/2014) For anyone interested a spreadsheet with the TRR scenario can be downloaded here just click on down arrow near the upper left to download spreadsheet.

A recent post at Peak Oil Barrel by Jean Laherrere suggested an ultimate recoverable resource(URR) for the North Dakota Bakken/Three Forks of about 2.5 Gb based on Hubbert Linearization. This conflicts with a recent (April 2013) USGS mean (F50) TRR estimate of 8.4 Gb. (See my earlier blog post.)

I decided to update my scenarios based on the range of USGS TRR estimates from F95=6 Gb to F5=11.3 Gb for the North Dakota(ND) Bakken/ Three Forks. Note that at year end 2011 there were 2.6 Gb of crude proven reserves in ND and at the end of 2007 about 0.5 Gb, I will assume all of this reserve increase came from the Bakken/ Three Forks, so 2.1 Gb of proven reserves added to 0.35 Gb of oil produced from the Bakken/ Three Forks gives us 2.45 Gb for a minimum URR. The Hubbert Linearization points to about 0.05 Gb of undiscovered oil whereas the USGS suggests 3.5 to 8.9 Gb of undiscovered technically recoverable resource(TRR) in the North Dakota Bakken/Three Forks.

Note that Mr. Laherrere has forgotten more about geology than I know. He may have information that I don’t have access to or has read the USGS April 2013 Bakken/Three Forks assessment and found that the report was not credible. I have assumed in my analysis that the USGS analysis is correct, if it is not then my analysis will also be flawed. I would love to hear from Mr. Laherrere about the specific problems he sees with the USGS analysis, I no doubt would learn much.

The EIA’s Latest Drilling Productivity Report

01/13/201401/30/2014 Ron Patterson 21 Comments

The EIA’s latest Drilling Productivity Report is out. Not a lot of changes since we now know that the EIA just guesses at the production for the last five months, August through December, then plugs in their estimate for the next two months, January and February. In the case of the Bakken they say December production was 1,003,578 bp/d and January and February will be 1,025,634 and 1,050,521 bp/d respectively. For Eagle Ford December production, they say, was 1,221,576 bp/d and they expect January and February production to be 1,251,617 and 1,285,224 bp/d respectively.

The below chart shows the Bakken production change from month to month. I have shortened the time displayed in order to better show the month to month change.

Notice the dramatic change in the January report for May, June and July. Obviously they looked at the real data and saw how different it was from what they had previously just plugged in, and made the necessary changes. They are saying that the Bakken had a really good December, slightly better than January, then things turn up again in February.

Here is the same chart for Eagle Ford.

Not such dramatic changes in the Eagle Ford production data. But notice they are expecting an upturn in January and December. We shall see.

Problems and Politics Keeping Crude Oil Production Well Below Expectations

01/02/201401/30/2014 Ron Patterson 24 Comments

OPEC December Crude Output Falls to 2-Year Low: Survey

Venezuelan Policies

Venezuelan production dropped 235,000 barrels a day to 2.45 million this month, the survey showed. The South American country pumped the least crude since October 2011. Resources have been diverted from energy sector into social welfare programs, sending production lower.

Petroleos de Venezuela SA, the state oil company, was purged after a two-month oil strike intended to oust President Hugo Chavez from power in 2003. Nicolas Maduro, who became president in March when Chavez died, has continued his predecessor’s policies.

“It’s hard to see how the situation in Venezuela gets any better,” said Bill O’Grady, chief market strategist at Confluence Investment Management in St. Louis, which oversees $1.4 billion. “Funds have been used to prop up the government instead of maintaining the oil industry since the PDVSA strike in 2003. It’s clear the country is on an unsustainable path.”

Data for the above graph is from the latest OPEC MOMR published last month and includes data through November 2012. It has Venezuela crude only production at 2,364,000 bp/d in November so it differs considerably from the Bloomberg report above. That report may be using production reported by Venezuela themselves which they reported as 2,854,000 bp/d for November or 490,000 kb/d above what the OPEC MOMR’s “secondary sources” said they produced.