The California-based Oil & Gas Innovation Center seeks out technologies developed in other industries that can be modified to suit the technology needs of the petroleum industry. The featured technologies are either commercially available or nearing the threshold.

The O&G Innovation Center offers a subscription service that provides online profiles, company-supplied power point presentations, podcasts, videos, written Q&A transcripts, and contact information. In addition, about a dozen new companies are invited to present each fall at an Innovation Showcase open

only to subscribers, recently held at Rice University. Projects at two of those companies are described here.

Chiral optical fibers are used to create different types of chiral fiber gratings, with varying periods depending on the degree of twisting. (Image provided by Chiral Photonics)

Chiral Photonics

The science of photonics involves the amplification, detection, emission, generation, modulation, sensing, signal processing, switching, and transmission of light. The term developed with the development of semiconductor light emitters in the 1960s and fiber optics in the 1970s, and came into common use with fiber-optic transmission of digital data in the 1980s.

The word “chiral” derives from the Greek word for hand, “ceir” (or kheir), indicating that a chiral structure has handedness?(i.e., either right- or left-handed) and cannot be superimposed on its mirror image. Twisting optical fibers produces chiral structures capable of selectively filtering and polarizing light.

Pine Brook, NJ-based Chiral Photonics Inc. (CPI), founded in 1999, is developing a new class of optical devices based on twisting glass fibers to displace discrete optical elements such as lasers, filters, and sensors. CPI says it has the unique ability to microform all-glass optical fiber devices that perform across challenging application and design constraints, including exposure to high temperatures, radiation, and corrosive chemicals, in high-power applications, and those with stringent form factors. The company has shipped sensors, polarizers, and interconnect products since 2006. CPI products could be useful in downhole (point sensing, DTS calibration) and downstream (furnace, process monitoring) applications.

Fiber-optic sensors offer several advantages. They are lightweight, impervious to electromagnetic interference (EMI), offer fast response time, present no ignition hazard, are resistant to chemical corrosion and have diverse sensitivities to elongation (pressure, strain) and fluid level.

Diffraction gratings, sensors

CPI developed new ultrahigh-temperature chiral diffraction gratings and a chiral point sensor that is stable to 1,831ºF (1,000ºC). The underlying technology includes all-glass fibers that are tapered and twisted with sub-micron precision. The fiber is twisted to form a helical (chiral) core and the twist profile determines the fiber’s functionality. The fibers are used to create chiral gratings with short periods (~1 mm) used in filters and lasers; intermediate period (~10 mm) used in polarizers; and long period (~100 mm) used in sensors. The sensors incorporate either single-helix or double-helix fibers.

The chiral point sensor has been tested during thousands of hours of cycling. The sensor system includes a sensor, interrogator, and software, and is available with four channels (four sensors) or 16 channels (16 sensors).

InnaLabs has designed a solid-state Coriolis vibratory gyro (CVG) comprised of a base (blue, at left), resonator (green, at right) with electrodes, and screw (yellow, center). Outer housing not shown. (Image provided by InnaLabs Holding Inc.)

CPI holds 18 patents with more applications pending, was listed by Red Herring as one of the top 100 Innovative companies in 2004, and has received US $2.8 million in federal research grants (National Institute of Standards and Technology, National Science Foundation). It is also interested in partnering opportunities.

Innalabs holding

This Dulles, Va.-based company was founded in 2001 as an incubator for technologies from the former Soviet Union, particularly inertial technologies used in navigation, such as:

• Coriolis vibratory gyros (CVG);

• Closed-loop pendulous

accelerometers;

• Fluxgate magnetometers;

• Inertial sensor systems; and

• Position and orientation systems.

CVG

Individual Coriolis vibratory gyros (CVG) could be combined to provide multiple axes inclinometer measurements in MWD tools. (Images from InnaLabs Holding Inc.)

Gyroscopes measure or maintain orientation based on the principle of conservation of angular momentum. They measure angular motion without external reference. Commonly, the inertial reference is the angular momentum stored in a spinning wheel, but in a CVG, the measure of rotation is provided by the Coriolis Effect on a vibrating mass. An example is the Foucault pendulum, developed in 1851.

The CVG is so named because as the plane of oscillation is rotated, the response detected by the transducer results from the Coriolis term in its equations of motion (a type of vibrating structure gyroscope). CVGs range from vibrating shell macro-sized devices to low-cost silicon and quartz chip micro-sized devices.

Innalabs has developed two different, single-axis Coriolis vibratory gyro systems and is working on a triple-axis system suitable for work downhole.

The design works on the premise of how a standing wave at the rim of a cylinder reacts to rotation about the center axis of the cylinder. Oscillation is created with electrodes at the bottom of the resonator, and the wave amplitudes are measured and controlled through a closed-loop system. The power required to maintain the oscillation in its equilibrium state is proportional to the rotation state being realized.

The core of the InnaLabs’ CVG is a simple, three-component system with no moving parts: a base, resonator, and electrodes at the bottom of the resonator, all within a compact housing (1.75-in. by 8-in.). The robust physical design does not require a clean room to fabricate.

Pete Tewksbury explained how the company’s CVG could be used for heading determination downhole, in measurement-while-drilling (MWD) systems. MWD applications need to be able to measure orientation even around magnetic disturbances.

In the InnaLabs design, the sensing axis, z, measures angle rate orthogonal to the mounting plane, in a dynamic environment. (The measurements can be used in inertial navigation systems to compute attitude and heading angles.)

The gyro output is a digital signal. Output data is floating point numbers that are proportional to average angular rate over a data sampling time. The output data must be divided by a scale factor to convert data to º/sec.

Company engineers in the Ukraine have incorporated metal resonators into the gyro design, but are experimenting with quartz. Using a quartz-based resonator will not require dynamic tuning, thus eliminating the need for moving parts. Q-factor testing of the quartz resonators have shown 0.01º/hour performance, which Tewksbury said is more than accurate enough for gyro compass work. Other criteria include azimuth accuracy of at least 0.5º, temperature tolerance to 347ºF (175ºC), and angular rate changes of 75º/sec.

Incorporating the quartz resonators into the Gyro is the next step, but that research step is not yet funded.

CVG is a tool widely accepted in industry that could be used effectively in drilling applications. IEEE already specifies standards for single-axis CVG use as a sensor (http://standards.ieee.org).