As the horizontal well increases in length, does it also increase in diameter? My family has interest in wells that are contained within sections (no more than 1 mile long). The operator has pooled one section with an adjacent section, and the monthly volume has greatly increased.
Decreases in diameter as it goes longer distances. A two section horizontal will have more perforations than a one section horizontal. And have much better production than a vertical well that has even fewer perforations. Also, they control the choke valve at the top of the well, so that could contribute. You may have a different reservoir than a previous well. Lots of potential reasons why the volumes may be different.
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Thanks so much for the info. Would the well’s rate of depletion be any different than a well in the same area but only half as long?
Depends upon whether it is gas or oil, the operator’s completion techniques and style of operation, the choke size, number of perforations and spacing, the reservoir pressure and so on and so on…Every well is slightly different, but engineers are able to use the previous history of a well and similar wells nearby with similar completion techniques to predict what a new well performance “might” be.
Think of a horizontal well as a series of 200’ (ish) frac stages. Each stage comes on at a high rate and declines quickly. In a beautiful heterogeneous world they all produce the same amount at all times from the cylinder of rock surrounding that 200’ of lateral. So a one mile well with 25 stages would produce half as much as a 2 mile long well with 50 stages at all times. It doesn’t really work that way because each stage isn’t exactly the same. Its harder the frac the stage 2 miles away, its harder to make fluids from the stage 2 miles away. So the one mile well tends to come on at a rate that is, say 75%, of the two mile well. But…over time…you should be contacting more or less 2x the reservoir in the 2 mile well and it will make roughly 2x what the one mile well makes. Which means that longer wells tend to decline slower.
For the 1 mile to (now) 3 mile range that is common, you probably are going to drill the horizontal with the same size bit. Same diameter. At least you do in the Delaware Basin. You definitely can’t run a smaller diameter casing in a longer well or your pump friction will kill you trying to frac the toe and it will also be even tougher to flow higher rates.
I’m assuming the question is not, does an individual well decrease in diameter with length (which yes, they all do as you Russian doll in the required casing strings), but is a longer well drilled with a bigger diameter in the horizontal than a shorter well.
I was also thinking Russian doll analogy or a pirate’s collapsing spyglass! Larger diameter at the top and smaller diameter . Each of the subsequent strings of casing has to hook into the one above it or be cemented all the way to the top.
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