Core-Quality LWD Data Identifies Additional Pay Within Carbonate Sequence in Deteriorating Section

Improve production decisions with accurate LWD data

Petroamazonas was developing the Coca-K field of eastern Ecuador and sought to expand production by exploiting secondary reserves. It identified a heterogeneous formation comprising limestone, dolomite, sand, silt, and clay in an existing well's 12 1/4-in section. The operator ran a triple-combo logging suite to characterize and evaluate the formation. However, because the formation included carbonates mixed with shales, the triple-combo data for porosity was inaccurate. Adding to the logging challenge was the condition of the borehole, which was deteriorating along the 12 1/4-in section. The operator sought a solution that would enable accurate characterization of the carbonate sequences in the section, allowing all feasible pay zones to be exploited.

Evaluate formation producibility in real time using proVISION Plus service

Schlumberger recommended running the proVISION Plus 825 service for the first time in the country. The proVISION Plus service provides lithology-independent porosity and continuous permeability for real-time assessment of reservoir producibility. Using T2 distribution, irreducible and producible fluid volumes can be derived for improved estimation of production rates. These capabilities are particularly important for determining permeability in heterogeneous carbonates and for identifying bypassed pay zones in shaly sands.

To ensure full characterization of the carbonate section, Petroamazonas ran the proVISION Plus service with a coring system so that the LWD data could be compared with laboratory core measurements. Drilling fluid experts from M-I SWACO, a Schlumberger company, helped optimize mud quality to ensure a smooth run. Additionally, petrotechnical and geomechanics experts offered Petroamazonas real-time drilling support. The team processed and QCed the data in approximately 24 hours, allowing timely decisions to be made while drilling.

Identified additional pay zone with core-quality measurements

Petroamazonas logged the interval in drilling mode with no interference from the coring operation. Despite the size and deterioration of the well section, the proVISION Plus service acquired logging data that accurately reflected the rock properties as confirmed by core analysis. This precise data provided insight that traditional triple-combo technologies could not in this reservoir type.

The proVISION Plus service also identified an additional sand body that was not expected for the geological sequence. The sand demonstrated good quality, adding additional producible reserves for Petroamazonas in the field.