Formation testing tools in wireline operations typically use hydraulic pump systems for fluid cleanup and sampling. As there is an electric connection and a communications channel suitable for interactive tool operation to the wireline systems, the operator interacts continuously with the system and can adjust the pump parameters to the downhole conditions. Due to the low bandwidth of the mud pulse systems this is not possible in the while-drilling environment. Moreover, the hydraulic concept makes a precise control of the pump parameters nearly impossible. To overcome this challenge a highly sophisticated pump and pump control system is necessary. A closed-loop control system and different intelligent algorithms avoid pumping below the bubblepoint and thus prevent the alteration of the fluid sample. In combination with pressure gauges the innovative pump control system delivers additional information about the downhole fluid. While pumping it is possible to calculate continuously the compressibility of the fluid and deliver a precise cleanup mobility. The pump control minimizes the backflow and mud valve switching force and it is possible to derive the effective volume pumped that corrects the difference between pump rate and flow rate. In this paper the capabilities and operation of this innovative pump system within the new logging-while-drilling (LWD) fluid analysis and sampling tool will be shown. It will be demonstrated that it is possible to run a fluid sampling operation in a nearly automated system. The continuous interaction of the operator with the system to control the pump process will not be necessary. The results from different field tests will be compared and the advantages of the system will be discussed. An outlook will be given how to implement this technology in further developments and how sampling tools can benefit from this technology in challenging environments like unconsolidated sands.

In recent years different new services for formation sampling while drilling operations were introduced. The provided and implemented technology is primarily focused on the delivery of representative single-phase fluid samples. The formation sampling while drilling tools are equipped with various unique fluid identification sensors. These sensor modules deliver multiple physical properties and are commonly used for clean-up monitoring. Due to the extended downhole time during long drilling runs and the tough drilling condition ruggedized sensor elements have to be implemented. In addition, the same challenges regarding pressure, temperature and size as with wireline tools have to be considered. The described logging-while-drilling (LWD) fluid analysis and sampling service is now extended by delivering optical absorbance spectroscopy and fluorescence measurements under in-situ conditions. This sensor system is added to the already existing sensor elements like pressure and temperature as well as measurement cells for density, viscosity, sound speed and optical refractive index. In addition, the lately introduced compressibility value derived from the electro-mechanical pump offers a bulk measurement, where localized sensors observe scattered data. As while drilling applications are often limited by the reduced bandwidth between the downhole tool and the surface acquisition system readings from the new optical sensor modules will be added to the fluid-typing algorithm, previously based on density, compressibility, refractive index and sound speed measurements, for improved predictions during sampling operations. This technology should expand the application of fluid analysis in the downhole environment, gaining a deeper understanding of the reservoir fluid as well as improving the reservoir characterization and classification. With the new optical sensor system which provides distinct wavelength measurements in the visible, near infrared as well as ultraviolet range, a more detailed analytics of the formation fluid is possible. It will enhance the differentiation between water based mud, formation water and injection water as well as oil based mud and oil. It improves contamination monitoring and delivers a more detailed chemical composition while sampling. This new sensors will increase the success of fluid analysis only jobs. Field examples will demonstrate the new sensor capabilities and will evaluate the data accuracy. The data interpretation allows for a broad comparison between different environments and the according sensor behavior. The review includes results from different reservoirs in various regions around the world.