New LWD Service Integrates Formation Fluid Analysis and Sampling
Authors: JPT staff _ 
Published: February 2015

Young Technology Showcase

Determining the fluid properties of a reservoir by using pressure/volume/ temperature (PVT) analysis is essential to petroleum reservoir studies, production equipment design, and reservoir recovery efficiency estimation. The properties of the formation fluid are used to determine reserves and to predict reservoir performance and economics. PVT properties such as bubblepoint pressure, gas/oil ratio, viscosity, oil formation volume factor, and detailed composition are important to well performance analysis, material balance calculations, reservoir simulation, and production engineering calculations.

Once the reservoir information is available, the well team makes the critical field development decisions. Conventional post-well wireline formation testing operations can delay decision making for days, sometimes months, depending upon the logistics involved in transporting a sample from the wellsite to a PVT laboratory. Additionally, wireline deployment is expensive in horizontal and highly deviated wells because of the extra time and equipment required to convey the tools to the test intervals.

Integration Benefits

The latest logging-while-drilling (LWD) technology integrates downhole fluid analysis and sampling with formation pressure while drilling (FPWD), thereby providing environmental, economic, time-saving, and data quality benefits over traditional methods of reservoir characterization. The integration enables three distinct services: real-time formation pressure tests, real-time in-situ measurements of fluid properties, and downhole capture and retrieval to the surface of fluid samples.

The real-time formation pressure testing provides important information on fluid dynamics within the reservoir, mobility measurements, and zone productivity predictions. It is also important for accurate gradient analysis. Measuring multiple formation pressures at different depths delivers a formation fluid gradient that makes it possible to find contact points between different formation fluids such as water, gas, and oil. Pressure testing in an LWD environment also provides important information for safety and drilling optimization, including data that are valuable for controlling hydraulic overbalance and equivalent circulating density.

Representative fluid samples provide information on the production potential of the reservoir. LWD fluid analysis and sampling enables fluids samples to be collected closer to in-situ conditions for a more accurate determination of fluid composition. Additionally, sample integrity can be monitored continually from the first time the sample enters the LWD tool until it is transferred to the laboratory for detailed analysis. Greater accuracy improves project cycle times and reduces development risks.

Although the vital information provided by the integrated LWD service is useful throughout the life cycle of a reservoir, it is particularly valuable during the initial assessment to determine the commercial potential of a project. The assessment includes estimates for producibility, fluid type and composition, fluid phase behavior, production facility design, and flow assurance.