Mike, the problem with using recovery factors based on Texas is that we gutted many of our early-discovered giant fields with overproduction.
Secondary and tertiary production and Maximum Efficient Rate (of recovery) were all invented by my homies in the oil patch around here. As a consequence the is a recovery factor of the oil in place of about 1/3rd, while the mid-east and North Sea are getting about 50% of the original oil in place.
The Bureau of Economic Geology at the University of Texas should have the exzact figures you are looking for.

Right I forgot about this. We really damaged our fields early on. In a sense its a blessing since fixing the damage is probably what keep us going. I don't think Texas by itself is all that useful as a model past a certain point because of this.