Eni Receives Industry-First While-Drilling Analysis of Hydrocarbon Composition, Gulf of Mexico

Identify new sampling method to save time and money in future operations

Eni US Operating Co. wanted to optimize formation testing processes to save time and money in future wells. The operator conducted a field test while drilling an exploratory well in the Mississippi Canyon area of the Gulf of Mexico in Miocene turbiditic sands. The target zone was located at a water depth of about 5,800 ft with uncertain reservoir characteristics and fluid properties. A new reservoir fluid mapping method would need to be capable of acquiring pretests, capturing clean downhole samples, and fully describing reservoir fluids at a cost and time savings.

Acquire individual fluid composition analysis up to C₅ with SpectraSphere service

Schlumberger recommended using the SpectraSphere service to measure formation pressures, acquire samples, and analyze the fluid characteristics in real time from the exploratory Mississippi Canyon well. This service is added to the downhole drilling assembly and collects reservoir-representative samples while performing accurate fluid analysis before sampling while drilling. Traditionally, sampling happens about a day after drilling, which often results in deeper invasion of the reservoir by the drilling fluid filtrate. The SpectraSphere service accurately delivers the following in situ hydrocarbons properties: individual compositions from C₁ to C₅, C₆₊, GOR, fluid color, hydrocarbons and water fractions, flowline fluid resistivity, temperature and pressure, and CO₂.

Transmitted individual hydrocarbon analysis in situ, delivered lab-quality fluid profiling

The SpectraSphere service analyzed and collected six samples downhole in real time, setting an industry first for the transmission of detailed in situ fluid properties. The SpectraSphere service estimated contamination and time to clean up, performed fluid identification and typing and measured GOR and fluid composition (C₁ to C₅, C₆₊, and CO₂).

These results were verified 10 weeks later by lab results. Contamination was estimated in real time to within ±2% of the laboratory-determined values. Pressure measurements and fluid gradients were also successfully obtained during the operation. A total of 28 pretests were taken—17 while drilling and 11 while pulling out—that provided Eni a full description of the reservoir pressure and fluid gradients.

By delivering lab-quality results while drilling, SpectraSphere service proved its capability of gathering good measurements and clean samples, saving Eni about 10 weeks.

PVT lab analysis results show good agreement with real-time, in situ analysis of fluid properties.

Eni determined that the quality and amount of real-time data (shown above) from the SpectraSphere service would enable it to accurately determine pressures, fluid composition, and fluid fraction in future wells.