6X for CO2 Storage Simulation

• CO2 solubility in water is a function of temperature, salinity, and mixing
• 6X internally calculates the CO2 solubility as a function of temperature and salinity using GENPV
• The mixing of CO2 with resident brine in thicker homogeneous zones occurs in a number of stages:
  • Normal solubility of CO2 in water as a function of pressure
  • A layer of dense brine forms along the interface of free CO2 and resident brine
  • As this dense brine layer becomes unstable, it sinks creating ganglia or fingers, forcing fresh resident brine to rise, setting up counter-current mixing/flux (constant flux stage)
  • Fingers merge creating sheets or plumes that sink in larger volumes
• Fingers occur at a scale that limits cell and timestep size. Using magnitude and frequency of fingering, mixing can be modeled using larger cells by specifying Rsw as a function of time

• CO2 moving through the reservoir will be trapped in rock pore space as a function of rock properties and hysteresis
• The volume of CO2 trapped is modelled in 6X by using residual gas saturation to scale both relative permeability and capillary pressure

• CO2 may be trapped as a solid precipitate in the rock as a function of rock mineralogy and rate of reaction
• The volume of precipitate and timing of precipitate formation is derived from laboratory data.
• The rate and volume of CO2 precipitation can be modelled in 6X using scripting and a dimensionless time function

• Free CO2 migrates up until it accumulates as free gas just beneath the reservoir seal / caprock
• CO2 may dissolve rock through a CO2-Water-Rock chemical reaction, increasing porosity and permeability
• This CO2-Water-Rock interaction may eventually lead to seal deterioration and leakage
• The changes of porosity and permeability are derived from laboratory data and can be modelled in 6X using scripting and a dimensionless time function

Quantification of uncertainty can be difficult and time consuming. Subsurface uncertainty exists from intrinsic geological complexity. A desire to quantify development options drives the successful application of Multiple Realizations; a pragmatic approach to optimize performance and maximize recovery from oil and gas reservoirs. It has successfully been applied from development appraisal stage projects to mature field projects and has increased project net present value.

6X Multiple Realization workflows

6X provides integrated functionality to create automated workflows performing hundreds of runs to quantify uncertainty in the following:

• Geological and fluid parameter sensitivities
• Experimental Design uncertainty quantification
• Assisted History Matching (AHM)
• Well and completion development selection
• Well and reservoir depletion forecasting

Unconventional reservoirs: well design to optimizing recovery

Many decisions are required to optimize recovery and economics from an unconventional well program. How many stages, how many clusters per stage, how much fluid and proppant to pump; how to determine the optimal well spacing and how many wells are required to develop a multi-bench drill spacing unit (DSU). A 6X Multiple Realization modeling workflow generates a range of outcomes to understand the hydraulic fracture growth and depletion to optimize EUR against net present value for a DSU.1

No hidden extras – a 6X license includes the MR module

The MR functionality exploits modern massively parallel architecture of 6X and runs on multi-CPU and multi-GPU systems. With the breakthrough and general availability of Cloud systems, clients can access 6X on Amazon AWS, Microsoft Azure and Google GCP.