Advances in logging and formation evaluation technology have resulted in customers who are satisfied with the results, partly because they have been developed with customer input to directly solve their problems. The big challenge now seems to be to keep up with growing demand.

Logging platform
The newest system has been 6 years in the making and is now being used around the world. The basic quad-combo tool suite is about half the length and two-thirds the weight of its former size and weight. Lighter weight and short length mean safer, easier handling for field personnel. Customers also enjoy significant rig-time savings: shorter rat-holes are needed, and rig-up and rig-down are faster. And, unlike some "short" tool offerings, the new system's downhole tools can operate continuously up to 350°F (176.6°C) and 20,000 psi, allowing customers to work over the full range of challenging environments. The hostile rotary coring tool is rated at 400°F (204.4°C) and 25,000 psi.

Improved downhole systems
The array-compensated true resistivity tool is one of the new components that is generating excitement. It includes fundamental sensitivity ranges from 6 in. to 80 in. and real-time processing software able to produce radial induction logs for depths of 10 in., 20 in., 30 in., 60 in. and 90 in. Logs are available with 1-ft, 2-ft or 4-ft (.3-m, .6-m or 1.2-m) vertical resolution. In addition, thermal and borehole correction protocols help the tool deliver accuracy and high tolerance under less than ideal logging conditions.
A new caliper tool is also available. This caliper enables log quality diagnostics, borehole volume calculations and assessment of borehole breakouts. Six independent, stylus-like arms and a high sample rate aid in its efficiency.
The platform also introduces a new telemetry system with a four-fold increase in bandwidth. This enhancement provides for faster logging speeds needed for current-generation high data-rate tools. This enhancement also paves the way for the development of several extreme data-rate tools that are now under design.
Three new imaging services are also getting on board. They are:
• Extended range micro-imager for images of a formation in openhole water-based mud environments. The tool has increased transmitter power, advanced digital signal acquisition and ultra low-noise electronics, resulting in better subsurface imaging over a wider range of logging conditions (Figure 1).
• Oil mud reservoir imager for images in open hole in oil-based mud. This tool generates electrical images of the formation similar to those generated by the micro-imaging tool. This service has required development of new and highly proprietary measurement principles. Improved borehole coverage is provided by six pads, each of which makes six resistivity measurements. Pads with three-axis articulation on arms with independent linkage provide excellent pad contact in washed-out, irregular boreholes.
• A cement and casing inspection tool for faster, improved interpretations of casing condition and cement-bond quality. This next-generation acoustic-scanner-type technology brings together digital electronics, advanced downhole signal processing and more powerful surface software to produce higher resolution 3-D images of both cement quality and casing integrity. It also acquires data with logging speeds of up to 60 ft (18.3 m) per minute. The tool offers a range of scanner heads for use in casings from 5 in. to 20 in. (Figure 2).
Two new, specialized probe features - the straddle packer and the oval pad - have been added to sampling and testing capabilities. These features have significantly expanded the operating range for sampling pressure-volume-temperature (PVT) fluids and pressure testing. The straddle packer sub (SPS) is an inflatable packer-probe module that augments the standard dual-probe sub for the Reservoir Description Tool (RDT) tester. The spacing between upper and lower inflatable isolation packers greatly increases the formation area in contact with the RDT tester and thus extends sampling capabilities to very low-mobility reservoirs and highly unconsolidated formations. Packer inflation times are now as much as 50% shorter than previous systems. The SPS sub has two independent intake ports, a redundancy that helps minimize the risk of having to abort sampling operations due to plugging. Operators can also circulate between ports and potentially observe fluid stratification in the annular space. Finally, the SPS packers have a special, new "power close" feature, which greatly reduces the risk of a stuck tool.
The oval pad is a modification of the standard dual-probe sub. Now, however, a single, elongated oval pad replaces two standard pads. The top of Figure 3 shows two probes, each with its flexible surrounding seal. The lower portion of the figure shows two separate ports contained within a recessed flow channel (labeled "425R") bordered by a sealing element.
The oval pad extends fluid sampling and pressure testing to lower-mobility reservoirs and involves only a fraction of the operating time, cost and risk. It is particularly useful in testing laminated formations where placement of individual, discrete probes can be problematic.
A new digital, software-controlled, fully combinable percussion sidewall coring system is also on the market. This system has no limit on the number of core guns that can be combined, and each gun can recover 29 cores. It's rated to 25,000 psi and 400°F. Key parameters related to shot integrity are recorded at the surface and alleviate shot uncertainty and "double-shooting" of core points.
Also available is a hostile rotary sidewall coring tool rated for 25,000 psi and continuous operation at 400°F. The standard non-hostile tool is a rotary coring device rated for 20,000 psi and 350°F (Figure 4). Both are software-controlled so that the tools can be fully automated or manually controlled. Both tools feature increased power at the bit and therefore decreased drill times.

Summing up
This new logging platform features improved operational efficiency owing to its lighter weight, short length and higher-performance downhole sensors. The formation imaging capabilities reliably cover both oil-mud and ultra-high formation resistivity/mud resistivity environments. Casing and cement inspection is now possible with improved fidelity and with much improved logging speeds. Two innovative designs have been introduced in support of fluid and pressure testing services. Both expand the operating limits for sampling, particularly to fractured and to low-permeability formations. The new designs also speed up operations and greatly reduce the risk of a stuck tool. Percussion and rotary coring capabilities have been extended to include hostile and very hostile environments.

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