Theta Newsletter - December 1998

XDIAG’s Unique Capabilities Explained


XDIAG is an expert diagnostic computer program. From a measured surface dynamometer card along with data for the well, XDIAG can diagnose the operating condition of the rod pumping system in great detail.

XDIAG generates a report in plain English that looks like a report written by a human expert. XDIAG has some unique capabilities that even human experts would have a hard time duplicating, such as detecting and correcting load cell errors, detecting possible errors with fluid specific gravity and fluid level, being able to accurately diagnose shallow high rate wells (Group 2 wells) and a lot more.

To be able to be as accurate as XDIAG in recognizing downhole dynamometer card shapes, a person must have the experience of correctly diagnosing over 50,000 dynamometer card shapes and never forgetting even one of them.

The Expert that never Forgets

Imagine a rod pumping system diagnostic expert that never forgets anything he or she has learned. Every time this person performs a diagnosis of a well, no matter how rare the pump problems he finds are, he always remembers the corresponding downhole pump card shapes.

Also, every few months this expert takes a course that teaches him the latest diagnostic techniques and makes him aware of any dynamometer card shapes that he has never seen, obtained from dozens of oil companies worldwide.

Would you be able to do your job better if your company had such an expert and you could instantly access his expertise or ask his advise any time you needed it?

This expert is XDIAG. The training I mentioned is done by us using a special software program that teaches XDIAG new downhole pump card patterns based on feedback I get from users like you. If XDIAG does not correctly identify a problem, first we analyze the case to find out why. If it is because XDIAG has never "seen" this downhole pump card shape, we add this new downhole pump card shape to the program’s pattern recognition database. If the problem is with the expert logic used to analyze the case, then we change XDIAG itself to correct the problem. Problems like this are rare now because of the large numbers of pattern already in XDIAG’s pattern recognition database, and because the expert logic of the program works very well.

However, we continue to add patterns to the program’s database to further refine it.

XDIAG is not perfect yet, but it is closer to perfection than any one human expert can be.

XDIAG’s Analysis of Group 2 Wells


An example of an XDIAG feature that is difficult to do without the program is the way XDIAG analyzes Group 2 (shallow high rate) wells. Normally, the diagnostic analysis of Group 2 wells is very difficult because of the distortion of the downhole pump card dynamometer card shape due to fluid inertia effects.

XDIAG analyzes group 2 wells with a series of powerful set of expert techniques. First, it determines whether the downhole pump card shows fluid inertia effects and also determines the best fluid compressibility index for the well. Then, it performs "surgery" on the downhole pump card to remove the effect of fluid inertia effects. Then, it determines what the transformed downhole pump card shapes shows.

XDIAG uses a similar technique to set horizontal lines on the downhole pump card after the fluid inertia effects are removed. This allows XDIAG to determine the fluid level and pump intake pressure more accurately.