Stories tagged with "water flood"

Reserves and Production: A Simple Example (based on Abqaiq in Saudi Arabia)

So far in this series of technical talks, I have tried to explain some of the pieces that have to be put together to get crude oil or natural gas out of the ground. I intend to go on with the series in the coming weeks, but thought that today I would put some of the different thoughts that I have talked about recently together. So I am going to talk a little about reserve calculations and production and will use an example to show how the numbers are derived. And again, let me stress that this is a very simplified example. It is also only somewhat fictionalized, as I shall comment at the end.

Let me start by assuming that I have a layer of rock that is 300 ft thick, five miles wide and thirty miles long.

Water Floods and Improving Oil Flow

This is part of Heading Out's Sunday tech talk series.

I am going to insert a topic here before going on to Carbonates, as I had mentioned doing in the last post, because it will help to explain a developing problem that comes when extracting oil from rocks such as chalk. And, because I used this example in my original post, let me again start by creating an analogy.

The oil business is one of great complexity and there are some challenges even in trying to explain some of the basic reasons why, when price goes up, producers can't just turn a tap and pull more oil out of the underground reservoir.

I was trying to think of a way of explaining it, and offer the following, in the hope that not too many of those who know reality will be offended at the simplification.

Way back at the beginning of the current Elizabethan era it used to be fun, after dinner, to float cream on top of coffee. I still do it when the cream is of the right sort, and it gives the coffee a different taste. Putting the cream over the coffee is a bit of a challenge, you start by using the back of a spoon, and when you get better pour it down the side of the cup.

The life of an oil reservoir

With your indulgence I am going to try and explain a little bit more about some of the stages that an oil reservoir might go through, to clarify some of the topics that have arisen in discussing oil production from large oil reservoirs. To do this I am going to build a simple model, to try and illustrate the odd point, concerning production and reservoir collapse. (This might help in understanding some of the debate between Matt Simmons and Jim Jarrell, as reported by Marco. Please bear in mind that this is a very simplified example, to illustrate the points - to those more knowledgeable, I apologize. But please jump in and clarify what I have not made clear or not explained correctly.)

Let me start by assuming that I have a layer of rock that is 300 ft thick, five miles wide and thirty miles long. Let us then assume that this has been folded in the middle, so that it now has trapped oil within all the pores of the rock. And, for the sake of discussion let's assume that it has a porosity of 20%. Now having found this reservoir - which is, let's say some 6,500 ft below the current surface of the ground - back some years ago, the oil moguls of the time decided to drill into it and extract the oil.