Flow experiments at reservoir conditions

GEUS reservoir condition rig.                                                      GEUS 3-phase separator.

The equipment has the following general specifications; however, the actual experimental set-up may alter the specifications:

• Fluid pressure, Pfluid, from 2 bara to 650 bara, Pfluid + Pconf cannot exceed 690 bara
• Hydrostatic confining pressure, Pconf, from 8 bara to 690 bara, Pfluid + Pconf cannot exceed 690 bara
• Temperature from ambient (~22°C) to 120°C, with stability better than 0.5°C. Core holder, pressure cylinders, a densitometer, and a 2-phase separator are situated inside a temperature-controlled oven to assure temperature equilibrium for these parts
• Tolerance to saline CO₂-rich brine and live oil within pressure and temperature specifications
• Flow rate between 0.1 ml/h and 400 ml/h with accuracy 1% of nominal rate. Shortly the flow rate may be increased to 900 ml/h
• Differential pressure across the sample measured with accuracy better than 0.05 bar
• Density of the fluid produced from the sample measured with accuracy better than 0.003 g/ml, provided that fines are not present in significant quantity
• Produced fluid volumes in a 2-phase system measured at reservoir conditions with accuracy better than 0.2 ml
• Produced fluid volumes in a 3-phase system measured at separator conditions with accuracy better than 1.0 ml. Separator conditions are Psep between 1 and 10 bara, and Tsep between 22 and 26°C
• Composite core samples of 38 mm core samples with length up to 45 cm
• Choice of horizontal vs. vertical flow direction in core
• Choice of 4 different injection fluids in the same experiment, e.g. water #1, water#2, crude oil and gas

During a flooding experiment, the following parameters are logged, usually with a logging interval of 1 minute:

• Pore-fluid pressure
• Hydrostatic confining pressure
• Differential pressure across the core sample
• Fluid-injection rate
• Cumulative injected fluid volume
• Density of produced fluid
• Cumulative separator fluid volume(-s) of the 2-phase or 3-phase separator as relevant
• Temperature of both core sample and separator
• Pressure of separator

Chemical characterisation and geochemical modelling

Flooding experiments may be combined with a sampling program for the chemical characterisation of the produced fluids. Fluid samples are usually extracted from the flow-line after passing the core sample. Typical sample size is 1–2 ml. Any gas phase present in the fluid will be lost during sampling. As an alternative, fluid samples may be extracted from the 3-phase separator, in which case the gas phase may also be sampled. GEUS’ Geochemistry Department or an external provider may conduct the geochemical characterisation. Examples of what GEUS offers:

• Custom-designed batch and flooding experiments to address chemical reactions in the reservoir due to changes in e.g. temperature, flow conditions, etc.
• Chemical sampling at ambient as well as reservoir conditions
• Geochemical modelling of laboratory data to help the interpretation of the laboratory data, e.g. calculation of saturation index and/or reactive transport modelling