Case Study: Focused Extraction Confirms Sweep Efficiency in Middle East Field

Pure fluid samples recovered with Quicksilver Probe focused fluid extraction confirm hydrocarbon recovery

Challenge: Confirm sweep efficiency of gas-cap expansion in a heterogeneous sandstone reservoir with 1-darcy permeability.

Solution: Analyze uncontaminated reservoir fluid samples collected with Quicksilver Probe focused fluid extraction for any remaining mobile oil.

Result: Verified high recovery efficiency through the analysis of samples collected with Quicksilver Probe focused extraction—no filtrate contamination and obtained in less than one-third the time of conventional sampling.

Confirming sweep efficiency in a complex reservoir

Several evaluation wells had been drilled to monitor sweep efficiency in a reservoir under gas-cap expansion drive and water drive. The objective was to evaluate the efficiency of the gas-cap expansion in the main reservoir, which is a heterogeneous sandstone formation with permeability that exceeds 1 darcy. Fluid analysis was planned to confirm that the sweep of the oil by gas expansion was highly efficient, as indicated by MR Scanner expert magnetic resonance service. The identification of any remaining mobile oil would reveal that the sweep was actually incomplete.

Extracting pure fluids in a fraction of the time

Quicksilver Probe focused fluid extraction collected pure reservoir fluids at four stations in the gas zone and one station in the oil column. The gas samples that were collected had no contamination by filtrate from the oil-base mud used to drill the well.

In the oil zone, the 650-ft3/bbl [117-m3/m3] GOR of the clean sample agreed with the accepted value of 660 ft3/bbl [118 m3/m3] for the field. The pumping time required for clean fluid extraction in the oil zones was about 1,600 s, approximately one-third of the time required by conventional sampling in this zone in other wells.

Verifying recovery efficiency

The pure fluids acquired by Quicksilver Probe focused fluid extraction were readily analyzed to provide new insight in evaluating the efficiency of hydrocarbon recovery in this mature field. The uncontaminated gas samples had no mobile oil, confirming the high recovery efficiency. Reservoir fluid composition was also documented, with laboratory analysis determining that the contamination in the oil sample acquired with Quicksilver Probe focused extraction was too small to measure.

Download: Sampling Confirms Sweep Efficiency in Middle East Field (0.47 MB PDF)

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