Mubadala Petroleum operates in the Nong Yao Field, which started production at Block G11/48 in June 2015. The field is located in Thailand with cumulative production to date of more than 12 million bbl [1.9 million m3]. The reservoir formation is a mixed sand-shale sequence with thin layers, including sand lobes of varying thickness, which are still capable of yielding sufficient quantities of oil for production. Started in May 2021 using a jackup rig, the Nong Yao A platform became a significant part of Mubadala’s drilling campaign and was a good place to test new technology that could bring major advances in operational efficiency.
The subsurface formations at Nong Yao present many challenges for horizontal geosteering, including structural uncertainty due to seismic time-depth conversion inaccuracies, sand thickness variations due to multiple stacking channels in target layers, and variable reservoir properties due to sand and shale-bed intercalation.
The subsurface formations at Nong Yao present many challenges for horizontal geosteering, including structural uncertainty due to seismic time-depth conversion inaccuracies, sand thickness variations due to multiple stacking channels in target layers, and variable reservoir properties due to sand and shale-bed intercalation. For most subsurface mapping applications, Mubadala Petroleum previously used the PeriScope HD multilayer bed boundary detection service as its standard technology to assist with geosteering in horizontal production zones. PeriScope HD service provides excellent mapping results in clean clastic and thick sand environments.
For areas with more complex lithology, thin layers, and challenging reservoir structures such as those in the Nong Yao Field, SLB recommended the PeriScope Edge multilayer mapping-while-drilling service. The PeriScope Edge service, which maps subsurface layers in real time as drilling progresses, is powered by a new set of features including deep resistivity raw measurements, deep anisotropy measurements, and a new and powerful inversion process. The PeriScope Edge service provides both a larger depth-of-detection range and higher mapping resolution in complex reservoir settings, giving clearer boundary delineation even in layers with a thickness of 3 ft or less.
The service’s deterministic parametric inversion (DPI) technology can map up to eight layers at a time, making it a fit-for-purpose solution for the complex lithology and thin layer reservoirs in this field. The combination of innovative inversion with measurements coming from the axial, tilted, and transverse antenna provides the fastest and highest detail of reservoir layers for evaluation of the formation while drilling.
Mubadala Petroleum had a total of four horizontal wells where it would be using the older generation technology but wanted to use the PeriScope Edge service in two of the wells due to the complex conditions anticipated while drilling through thin sand lobes.
Using the PeriScope Edge service, the Mubadala Petroleum subsurface team created a real-time inversion map clearly showing the interbedded thin layers of sand and shale while resolving multiple boundaries with higher resolution than was previously possible. Using new deep-resistivity raw measurements from the PeriScope Edge service, the conventional propagation resistivity curves were not required as input for the inversion, eliminating some artifacts caused by polarization effects and producing a much cleaner inversion. The improved multilayer mapping gave even more confidence to the subsurface team for improved geosteering decision-making.
PeriScope Edge service improved drilling optimization by enabling the operator to effectively gain enough production length, mapping the target areas with best pay while avoiding the risk of drilling out of the sand layer due to multiple stacking channels and complex thin reservoirs.
