Comparison of the pumpout volume, volume fraction, and GOR plots for the Quicksilver Probe fluid-acquisition flowline and guard flowline shows how the guard pumping diverts contaminated fluids from the central acquisition probe.
Quicksilver Probe focused technique acquires samples with <1/10 the contamination of conventional probe samples
Challenge
Acquire a pure sample of formation fluid to enable better understanding of fluid properties before conducting the deepest well test in the Gulf of Mexico.
Solution
Collect pure fluid samples with Quicksilver Probe fluid extraction for comparison with the discovery well to improve fluid properties estimation and test design.
Results
Refine viscosity estimate to optimize the deepest successful well test in the Gulf of Mexico by using Quicksilver Probe samples with less than 1% contamination recovered after only 4 h of pumping.
Reducing uncertainty and risk in test design
Chevron had planned a well test in its deepwater Jack 2 well that would make it the only Lower Tertiary well ever tested in the Gulf of Mexico. Drillstem tests are rarely performed in this region—especially in subsalt—because they typically cost at least USD 70 million in wells that are already difficult to drill and complete. Acquiring a pure sample of formation fluid would enable a clearer understanding of fluid properties before the production test to greatly reduce many uncertainties and the overall risk in the test design.
Collecting pure reservoir fluids
Schlumberger configured a sampling toolstring to collect conventional fluid samples at two stations with an extralarge-diameter probe and focused samples at two Quicksilver Probe stations. Real-time analysis of flowline fluid at one of the conventional probe stations showed that the GOR increased, but never leveled off, even after 8 h of pumping. Samples were collected 20 min later, and subsequent laboratory analysis found that they had more than 10% contamination with oil-base mud. Samples acquired at the Quicksilver Probe stations had less than 1% contamination after only 4 h of pumping.
Optimizing for success
Comparison of these ultrahigh-quality samples with those from the Jack 1 discovery well improved the viscosity estimation over the value obtained from conventional sampling.
The test design was further refined by quantifying the GOR for the separator and surface facilities, predicting PVT behavior, and enhancing reservoir characterization. The Jack 2 production test, completed in September 2006, was the deepest successful well test in the Gulf of Mexico. During the test, the well sustained a flow rate of more than 950 m3/d [6,000 bbl/d] of crude oil from about 40% of the well's net pay.
