The Rising Influence of Rising Affluence

[OakesCS]

Dew,

Perforating involves ignition of a shaped explosive charge which penetrates tubing, any cement that happens to be in the way, and some part of the rock. It's done to introduce stimulation fluids into the reservoir rock and to allow flow of fluids from selected parts of a reservoir into the production tubing. The explosive charges are effectively identical to some types of anti-tank weapons and some of the rocket propelled grenades that you see certain folks walking around with in Afghanistan and Iraq. Consequently, some field engineers who deal with these things occasionally get special treatment in airports after they set off the sniffer alarms.

The charges can be arranged in different geometries and spacings and for different penetration depths, e.g. look at the picture on the upper left of the page at http://www.slb.com/services/perforating.aspx

a good animation is at (~1:20 mark):

As the CLB guy says: setting off explosives in a hole can produce results that are not quite optimal, e.g. rather than getting nice neat holes, the rock or cement can fracture around the holes and those fractures may go to unwanted places. That can allow undesirable fluids to enter the well or compromise the integrity of the well. Since i'm not a perforating guy, I don't know why the toe of a well would be particularly difficult.

John Daniel's question about coiled tubing conveyance replacing wireline was a bit idiotic. I'm hoping the guy isn't an industry investment analyst. Gas shales are frequently (if not generally) horizontal so to optimize production the wells are horizontal. Since gravity doesn't work so well for wireline tools in horizontal wells coiled tubing is frequently used. Coiled tubing is just what it sounds like. It has enough strength that it can be used to push stuff down a hole. It can be used to drill wells as well.

There's nothing really new about what the CLB guy was describing. I have no idea whether or not they really invented the technology. I've heard enough of those sorts of claims that I give them very little credence.

Development and testing of perforating tools looks like a lot of fun.
cheers,
charlie