The application of chemical stratigraphy in High-Pressure, High-Temperature (HPHT) hydrocarbon systems

High-Pressure, High-Temperature (HPHT) hydrocarbon systems were once overlooked but are becoming increasingly viable prospects with the advent of new technologies. HPHT wells present many technical challenges for operations geology. In addition to greater drilling depths and subsurface uncertainty, extreme pressures and variable pore pressure profiles typically necessitate specialised drilling programs.

Dan Atkin, Senior Reservoir Geologist & Chemical Stratigraphy Co-ordinator

22 May 2020

One such innovative program includes that of the Shearwater Field, UKCS, where RPS have successfully applied our chemical stratigraphy service to great effect (Atkin et al., 2020). In this example, chemical stratigraphy proved highly effective in resolving subsurface strata and, more importantly, provided a backup GR (Gamma Ray) data source in an environment where conventional tools were either absent due to drill-string configuration or at risk of failure due to the harsh conditions. The net result was a reduction in subsurface uncertainty/risk and a significant time/financial saving through the reliance on robust synthetic GR data.

The application of this technique shows great promise for expansion into other HPHT systems. Whether that comprises other local fields in the Central North Sea, Viking Graben plays in the Norwegian North Sea, Halten Terrace wells in the Norwegian Sea, or further afield in the United States (deep water Gulf of Mexico and deep, hot onshore wells). These systems and other HPHT regions across the world could potentially benefit from the approach, or indeed any situation where backup GR data is of value. Typical benefits to the technology might include:

  • Reduced subsurface uncertainty through critical sections.
  • Lowered risk associated with drilling ‘blind’ through Drill in Liner (DIL) sections.
  • Backup data source in the event of LWD malfunction.

Assessing the suitability of the chemical stratigraphy technique in each new area is relatively simple, requiring the analysis of one or more offset wells to enable the construction of a geochemical zonation framework. With the addition of each new well and accompanying data, this framework can be further refined and improved, creating even greater confidence. Use of the Synthetic GR parameter, however, requires no legacy data and can be applied with relative ease from the get-go. Ultimately, these combined techniques present a valuable dataset that has the potential to reduce subsurface uncertainty and associated risk. Additional benefits from employing a backup GR log option also provide significant cost-saving potential and peace of mind in the completion of technically challenging wells.   

If you believe RPS can support you in this area, contact Dan at daniel.atkin@rpsgroup.com

 

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