Marcellus Shale Operator Receives At-Surface Formation Evaluation in Near-Real Time | SLB

Marcellus Shale Operator Receives At-Surface Formation Evaluation in Near-Real Time

Published: 07/17/2015

Blue hero texture

Evaluate reservoir with significant TOC and mineralogical variations

An operator drilling a lateral well in Pennsylvania needed to evaluate rock and fluid heterogeneity along the planned trajectory targeting the Marcellus Shale. The well was planned to target a section of the Marcellus Shale with a high total organic carbon (TOC) concentration of up to 20%. The operator needed to analyze the mineralogical and geochemical composition of the formation to precisely steer the horizontal well within the target zone and optimize the fracturing strategy.

Accurately evaluate formation at surface from cuttings

Schlumberger recommended characterizing the mineralogy, elemental composition, and TOC of the reservoir with the LithoFlex service from Geoservices, a Schlumberger company. This wellsite laboratory-quality evaluation method provides accurate and repeatable evaluation of cuttings immediately after they reach the surface, avoiding conveyance issues and exposure to additional operational risk.

Marcellus Shale Operator Receives At-Surface Formation Evaluation in Near Real Time
This ternary diagram from the LithoFlex service reveals the heterogeneity of the rock, and the color of the plot points indicates the brittleness of the cuttings sample. Together, this information can be used to improve completion design.
Log provided by the LithoFlex service showing geochemical fingerprint.
Logs from the LithoFlex service provide objective measurements of cuttings to improve the operator’s understanding of the formation. The TOC concentration (Track 4) indicates zones of superior production potential, and the formation top changes (Track 12) show which intervals were drilled out of zone.

Provided information critical to optimizing fracturing design

Through analysis of cuttings samples, the LithoFlex service identified lateral variations in mineralogy and TOC and revealed zones of superior production potential. Logs from the LithoFlex service confirmed that the lateral was landed in the target zone. Providing further proof that the well was landed in the Marcellus Shale, TOC concentration exceeded 10%, and the concentration of redox proxies, such as molybdenum and uranium, increased.

Measurements of brittleness from the LithoFlex service identified brittle zones that the operator can use to optimize the fracturing strategy of this well. Additionally, the LithoFlex service identified intervals where the lateral was drilled out of zone. The changes in formation are indicated by spikes in calcite, as shown in the log, and provide valuable information for optimizing completion design.

Marcellus Shale, United States, North America, Onshore

Challenge: Assess rock and fluid heterogeneity in the complex lithology of the Marcellus Shale while drilling a lateral well.

Solution: Use the LithoFlex multifactor shale-cuttings evaluation-while-drilling service to conduct formation evaluation from cuttings at surface.


  • Received at-surface characterization of lithology of a lateral well in near real time and outside of the critical drilling path.
  • Located zones with optimal production.
  • Identified brittle zones and formation tops.
Products Used