40 March/April 2008 D R I L L I ND R I L L I N G C O N T R A C T O R

I N N O V A T I N G W H I L E D R I L L I N G

Halliburton’s next-generation LWD sensors read faster, clearer and deeper into formation THE INSITE GENERATION, being launched by Halliburton’s Sperry Drilling Services, is a new generation of LWD sensors and applications that provide deeper reading, higher resolu-tion measurements with faster telem-etry and greater reliability, said Blaine Comeaux, Sperry global marketing manager. Advanced miniaturization tech-niques have been used with the InSite Generation to reduce the number of com-ponents while increasing power.

So far, three InSite sensors have been made available: the azimuthal deep resistivity (ADR), the azimuthal focus resistivity (AFR) and the IXO .

The InSite ADR is a deep-reading (up to 18 ft) resistivity device that can measure in 32 directions around the borehole. “That means if we detect a change in resistivity, we can tell whether that’s happening above us, below us, or to the sides. That allows us to geosteer much more effectively with much earlier warning of changes in bed thickness, dip angle and approaching water ,” Mr Comeaux said.

Legacy LWD resistivity tools are omni-directional and can detect a change in resistivity but cannot tell the driller what direction to steer because no directional information is available . “The traditional LWD resistivity tools take measurements in all directions around the borehole, giv-ing you one answer,” he said.

The InSite ADR not only measures in 32 directions, it also has 14 depths of inves-tigation up to 18 ft. “ Not only can we tell in what direction the adjacent formation change is, we can tell how far away it is . We can also steer to the highest resistiv-ity layer within a payzone to maximize our recovery.” With early warnings of changing lithology and geologic struc-ture, well trajectory can be corrected to run parallel with bed boundaries at a fixed distance. When crossing faults that are too small to be detected by seismic surveys, measurements from multiple depths of investigation can be used to delineate the different strata so correla-tion can be continued across the fault.

Applications for the InSite ADR include:

• Maximizing production in complex geology while refining the earth model.

•Navigating reservoirs with direction, dip angle and lateral thickness varia-tions.

• Maintaining desired distance from bed boundaries.

• Minimizing geological sidetracks.

• Detecting water zones and avoiding contact.

The second sensor, the azimuthal focus resistivity (AFR) provides high-resolu-tion images of the borehole and near-borehole area. It’s designed for used in water-based muds and is useful for picking up distinct characteristics of the rock when drilling through thin beds. In thinly laminated formations, with sand layers a few inches thick interbedded with thin shale layers, the InSite AFR ensures the accurate calculation of the net thickness of oil within a large column and therefore improves the accuracy of reserves calculations, Mr Comeaux said. “It also can help detect fractures and fracture orientation so you can steer the well more accurately to position it for the highest production.”

Finally, the third InSite Generation tool is the InSite IXO, an interface to Grant Prideco’s IntelliServ Network that can provide two-way communication between downhole LWD sensors and the surface at 57,000 bits/sec. That’s up to 10,000 times faster than current mud pulse telemetry rates, Mr Comeaux explained, meaning “bi-directional communication in milliseconds, with the pumps on or off and even during connections, while tripping, during well kill procedures, leak-off tests and while drilling ahead.” The ability to transmit at up to 1 MB/sec is expected to become available in the near future.

The ability for transmission of high-res-olution LWD data at broadband speeds also opens up potential for seismic while drilling technology. Seismic data acquired ahead of the bit reveals poten-tial pressure hazards, allowing danger-ous situations to be avoided.

With the IXO, high-speed data from drilling optimization sensors, such as pressure-while-drilling (PWD) and drill-string dynamics management (DDM) can provide new levels of understanding of the total drilling process while increas-ing safety and operational efficiency.

Another benefit of the IXO is that drillers don’t have to limit rate of penetration in soft formations just to gather LWD data. “This also opens up all sorts of real-time decision-making potential,” Mr Comeaux said, “with every bit of data gathered downhole available in a real-time center so the asset team and service company can see the full drilling and geological picture in high resolution .”

The InSite AFR sensor produces high-resolution images for identifying dip, fractures and borehole breakout as well as providing at-bit resistivity for improved casing/coring point “geostopping.”

The InSite ADR sensor acquires directional resistivity measurements 18 f t into the formation for high accuracy well placement and maximum production.