Advances in MWD-LWD data capture, telemetry technologies inspire increased application amid burgeoning current escalation in drilling
With current record-breaking oil and natural gas price increases having been sustained for at least a year by the effects of basic supply and demand, producing companies around the world are driving exploration and development drilling to peak levels, particularly offshore and in other, increasingly difficult environments. This has resulted in greater capital risk, a nascent shortage of rigs and a significant rise in overall drilling and completion costs.
Producers’ higher capital outlays for increasingly deeper wells that include significantly more multiple extended-reach horizontal well paths, combined with correspondingly higher bottom hole temperatures and pressures, have made nonproductive, or “slack” drilling time a major cost reduction issue.
Operators are using every available option to minimize such delays, constantly stressing the need to keep the drill string in the hole longer to tighten the time interval between spud point and completion. More robust drilling fluid pump capacity and more dependable drilling equipment and tools, from tubulars to bits, are helping to extend productive rig drilling time between round trips. In recent years, bottom-hole assemblies outfitted with more sophisticated downhole motors and new rotary steerable systems have increased penetration rates significantly, as well.
But this emphasis on speedier hole making also has increased the demand for delivery of critical borehole and formation data to the surface much sooner, both for safer, more efficient drilling dynamics and to generate detailed, more accurate downhole geological information for use in further well planning and completion strategies. The ultimate goal, of course, is to maximize production while drilling fewer wells.
Accordingly, instead of having to remove the drill string from the hole to take independent measurements and logs, operators now prefer to generate them with special tools included in the drill string itself that transmit data to the surface while the wellbore is being drilled. For this they rely on contracts for measurement-while-drilling (MWD) and logging-while-drilling (LWD) technology provided by service companies. Some also purchase or lease such technology and equipment outright from specialty tool manufacturers.
What’s more, producers are using MWD-LWD technology to guide extended-reach wells along extensive paths into specific reservoir sections to improve production from existing fields by tapping previously passed-over production and/or reaching additional reservoir “sweet spots” revealed by new tools and techniques for both geophysical and well log data interpretation.
For more than two decades, the market for integrated MWD-LWD technology has advanced in line with rapid acceleration in computing power, electronics designed to survive severe downhole conditions, enhanced sensors and refinement of the capability to provide downhole communication and deliver digital well data to the surface in real time, rather than waiting while tools are tripped out of the hole to extract the data from memory.
Such related technology improvements have enabled service-providers and equipment manufacturers to gradually win petroleum engineers, geoscientists and producing company management-many of them long steeped in “conventional” wireline, coiled tubing and inside the pipe-conveyed measurement and logging technology-over to the real-time “while-drilling” column.
Also, the seasoning of the technology has stemmed from lessons learned during years of actual field application, and many early MWD-LWD limitations are no longer relevant. For example, individual tool collar and sub lengths are shorter these days, thanks to the integration of multiple sensors in single mandrels. What’s more, the data transmission rates of mud-pulse and electromagnetic (EM) telemetry systems developed originally for MWD-LWD data have been improved significantly in recent times, delivering more reliable downhole measurements at a faster rate than before. Companies also continue to fashion smaller electronics packages to bring logging sensors closer to the bit.
Nevertheless, the search for altogether different telemetry systems still goes on, as well. One such breakthrough, for example-wired pipe telemetry-is only now just being introduced for commercial use, combining the best data rate speed and information capture benefits of hard wire technology with the protection, strength and stability of thick-walled drilling tubulars (see story, page 5). Moreover, still other new forms of MWD-LWD telemetry currently are under development for possible future commercial application.
So, the degree of refinement of MWD-LWD technology has continued to be honed to a finer edge, particularly during recent years and months. Challenged by operators’ demand for even more real-time borehole and formation data from freshly drilled well sections, individual service companies and measurement/logging tool manufacturers have concentrated significant research and development (R&D) dollars to meet that demand with whole new suites of MWD-LWD tools and operating platforms.
As a group, however, those same companies share a common goal of developing new ways to provide oil and gas producers with MWD-LWD technology innovations to increase their ability to reach productive reservoirs far below the earth’s surface. They hope to do so with the same precision that the aerospace industry has conducted its successful efforts to guide rockets, manned vehicles and space probes to targets far beyond the planet’s outer boundaries.
