EIA’s estimates for state crude oil production account for incomplete, lagged data
There are several reasons why the TRRC's initial reports tend to be low. For one, some reports are placed in a pending file while waiting for other state reporting requirements to be satisfied. In addition, there are always delinquent reports from oil and natural gas operators and reports with discrepancies that take time to resolve. Each month, Texas posts its own calculation of how low its initial estimated production values are. In addition, EIA has for several years measured the change in reported volume from month 1 to month 24, showing an average increase of 30%. These issues are eventually resolved, and the production data are incorporated into TRRC's published reports, generally over the course of about two years.
It is also important to note that EIA's published estimates include lease condensate, while some tables that TRRC provides tabulate crude oil and lease condensate separately. Condensate accounts for about 15% of the total crude oil and condensate volumes produced in the state of Texas.
http://www.eia.gov/todayinenergy/detail.cfm?id=22012