Laminated reservoirs – what can you do with pesky LWD data?
by David Maggs, Schlumberger
was presented on Wednesday the 10 th of January, 2018.
Laminated or thin bed reservoirs provide multiple challenges for petrophysical evaluation. By definition the beds are thinner than the resolution of the logging tools and therefore their properties are not fully resolved by the measurements.
The situation is further complicated when the measurements (especially resistivity) do not return the correct average value of the multiple beds they are investigating.
There are two main approaches to determine the correct petrophysical answers in these reservoirs, which I will label “sharpening” and “the big picture”. In the sharpening approach a high resolution log, normally a borehole imager, is used to define the bed boundaries and then the lower resolution logs are sharpened to match. Log convolution is used to ensure the log bed boundary responses are respected when sharpened. After sharpening standard petrophysical algorithms are used to solve for porosity, saturation etc. The big picture approach makes no attempt to define the formation properties in individual layers, but focuses on ensuring that the correct average properties are obtained in an interval. An example would be the use of tri-axial induction tools to determine the horizontal and vertical resistivity of the formation, and then used to determine hydrocarbon volumes and saturations.
The approaches mentioned above have been available for some time and are regularly applied to wireline data in vertical wells. But in these days of tight budgets and high angle and horizontal wells such data is not always available. The talk attempts to demonstrate how the sharpening and big picture approaches can be modified and applied to use LWD data in vertical, high angle and horizontal wells through a series of case studies and examples.
David Maggs, CV
David Maggs, received his Master’s in Mechanical Engineering from the University of Southampton, England in 1988. He has 29 years of experience in the oil industry, all with Schlumberger. He started as a wireline field engineer in South America for 5 years followed by a further 3 years in the Southern North Sea. David then moved to support Logging-While-Drilling (LWD) and well placement in the Gulf of Mexico. He was then transferred to the Data & Consulting Services segment as operations manager for Continental Europe, and later Latin America South. In 2004 David returned to Drilling & Measurements (D&M) as an LWD Domain Champion, completing assignments in Malaysia, Venezuela and Saudi Arabia, where he was responsible for the technical sales and support of a wide range of LWD technologies. In 2011 David moved to the Schlumberger Information Services (SIS) segment as Petrophysics Product Champion, based in Montpellier, France. Working on the Techlog software platform he was responsible for the development and implementation of several petrophysics modules, in particular the 3D Petrophysics module for high angle and horizontal well interpretation. He has been the Petrophysics Domain Head for D&M since summer 2014. David is a member of the SPWLA, and SPE.