Improvements to Data Acquisition and Bottomhole Fluid Sampling in Offshore Drill-Stem Testing

Abstract

Drill-stem testing (DST) is a proven method for reservoir characterization, which is important when designing well completion, future development strategies, and stimulation needs. If the completion designer has the ability to acquire accurate knowledge of fluid behavior as the hydrocarbon is produced to surface, decisions concerningcompletion strategies and expectations during well life can be greatly facilitated. The capability to collect a single-phase sample also is critical to reservoir modeling, as is achieving correct analysis of collected reservoir fluidswith accurate data collection frombottomhole gauges. Samples must remain as single-phase fluid samples during recovery, and introducing high-pressure nitrogen behind the sample helps maintain sample pressure. By monitoring nitrogen-charge pressure in the sampler carrier, the exact time the samplers are fired is known. Thus, monitoring gauges will show any abnormality such as whether the annulus was pressurized or if the samplers were fired at an unwanted moment. By integrating the sampler carrier gauge with a wireless acoustic data-acquisition system, status and confirmation of success of the trigger device are provided. Also, casing-pressure limitations are reduced by actuating downhole tools using acoustic telemetry instead of annulus pressure. This paper discusses offshore field operations in Brazil to illustrate the importance of correlating gauge data from sample well fluids with a wireless acoustic telemetry system, and also, how the successful application of a wirelessly controlled DST work string composed of a data-acquisition system, an acoustically controlled tester valve, and samplers can significantly improve well-testing strategies.

Potential Application of Fe2O3 and Functionalized SiO2 Nanoparticles for Inhibiting Asphaltene Precipitation in Live Oil at Reservoir Conditions

“…The conventional sampler does not maintain fluid pressure above the threshold pressure of asphaltene precipitation while the sample is being retrieved to the surface; , thus, representative sampling is a prerequisite for asphaltene characterizations and studies. The collection of a nonrepresentative reservoir fluid sample may carry a nonrepresentative asphaltene amount because of the irreversible nature of asphaltene precipitation. , The most reliable reservoir sampler for studying asphaltene behavior is proposed to be a single-phase reservoir sampler (SRS) or one-phase sampler (OPS). − In addition, in the face of the extensive studies executed on the effect of iron oxide and silica-based nanoparticles on asphaltene precipitation, the feasible use of these types of nanoparticles at real pressure and temperature conditions has been grossly missing in the literature.…”