Coupling high quality gas extraction with an extremely precise light hydrocarbon chromatograph, G5 enables GEOLOG to make the most of the C1-C5 gas spectrum. The utilization of standard mud logging crews working within the framework of proven quality control and analysis procedures yields very reliable, accurate data. The results can be related to formation fluid composition in a quantitative way when used with the constant volume mud trap, mud heating, and delta gas features of the service.
In challenging High Pressure High Temperature wells it can be difficult to perform formation evaluation with Logging While Drilling (LWD) tools where extremely heavy weight oil based muds affect logging or temperatures may exceed tool specifications.
At a minimum, the use of the G5 service can obtain gas data at surface from the “first breath” of the well while drilling. Resulting in unaffected data from well conditions and reducing risk by utilizing an at surface solution.
With reduced budgets operators are forced to make changes in formation evaluation programs. Downhole sampling programs can be extensive and costly.
The G5 service serves to reduce time, and costs for these downhole sampling programs. Inherently the service is provided at surface with no increased risk, yet provides clear continuous formation fluid identification. Allowing operators to pick and choose only the necessary pretest and sampling points to further refine the reservoir and reduce time downhole.
This service supports exploration and appraisal wells by maximizing the quality of light gas data. In development projects G5 can provide useful well correlation models on gas trends.
The system has a track record in all environments comprising ultra-deepwater, arctic, desert and tropical operations for evaluation of clastic, carbonate and unconventional reservoirs.
To improve the reliability of the GWDTM interpretation, a predictive model based on the relationship between mud gas ratios and PVT derived results was defined using data sets from ENI E&P reference wells drilled in the Kutei basin. The model applied on the offshore Indonesia wells describes a well-defined crossplot (Formation Fluid Prediction Crossplot or FPC). The data recorded in Real-Time enabled the identification of three different fluids (gas, oil, condensate) in different sections of the well. The technique is calibrated for individual basins.
Figure 1. The Green, Yellow, and Red blocks outline the predictive model developed in the Kutei basin for determining fluid typing.