Petrographic and diagenetic studies

Preparation and Sampling

Fugro Robertson can design sampling strategies based on client requirements using core information (lithology, core analysis data, facies) to selectively sample the core. Fugro Robertson has a long history of producing high quality standard thin sections (typically impregnated with blue-dyed resin to highlight porosity and with selected stains for minerals) for petrographic analyses. Polished thin sections/wafers and other services can be provided by Fugro Robertson from cuttings, sidewall cores and core pieces/plug trims.

Apatite and chlorite cements under SEM

Apatite and chlorite cements under SEM

Petrographic Description

Fugro Robertson provides a full range of petrographic descriptions including visual estimates or fully quantitative descriptions of mineralogy, porosity and sediment fabric. Particular emphasis is placed on the characterisation of pore systems, and evolution through time. (including porosity loss calculations). Methodologies can be optimised for specific work programmes. Results are routinely produced in a digital format and supplemented with a full range of illustrative materials.

Diagenetic studies

The key to defining reservoir risk from diagenetic study is to determine the timing of diagenetic events including hydrocarbon charge. In addition spatial distribution of hydrocarbons is also a necessity in order to investigate diagenetic processes in water zones. The evolution of the pore system is determined by gaining an understanding of the following by petrographic analysis of thin sections:

  • Cementation history of primary pores (cement mineralogy and phases)
  • Modification of primary pores by dissolution
  • Creation of secondary pores by dissolution of grains and/or bioclasts
  • Cementation history of secondary pores (cement mineralogy and phases)
  • The point at which effective diagenesis ceased because of hydrocarbon charge or other reason such as closing of diagenetic system

SEM (including EDAX and BSE) and XRD analyses are routinely integrated into our petrographic and diagenetic studies.