Regional Drilling

Home>Topics>Regional Drilling
Refine Results
  1. All
  2. Online Articles
  3. Magazine Articles
  1. Subsurface data technology advancing at dizzying pace

    The dizzying pace of technology advancement in the oil and natural gas industry’s ability to process, interpret, and image subsurface data shows no sign of letting up. Innovations abound, from wide-azimuth 3-D surveys designed to image reservoirs below complex salt bodies, to new wireless land sensors engineered to capture the full 3-D waveform, to ultrafast migration algorithms to enable interactive modeling in time and depth domains. An especially intriguing trend has been the industry move toward integrating seismic data with other kinds of subsurface data, helping operators to gain an even more comprehensive view of the subsurface. Subsurface data processing  The most significant recent technology advances in subsurface data processing are the tools for integration and data mining that are applicable through the life of the field, according to Geotrace CEO Bill Schrom. “Through technological convergence, linking seismic data to other subsurface measurements increases the accuracy and resolution of subsurface images,” he says. “Historically, seismic data was the tool of exploration. As the demand for hydrocarbons has increased, improved exploitation of existing fields has come about through improved reservoir management. The goal of optimization has created a need for new tools that increase the accuracy of the subsurface imaging.” Among those tools Schrom cites are depth imaging, prestack seismic inversion, and pore pressure estimation. He describes depth imaging as the technology to see the true geology below salt bodies or any abnormal velocity layers and adds, “Time image is imperfect because it is distorted, especially reserve time migration and prestack depth migration.” As for prestack seismic inversion, Schrom contends that the joint inversion of seismic and potential field data is emerging: “This inversion employs multiple input data types and potentially will make prestack inversion more robust, especially when well data are limited.” He points to Geotrace’s RockRes simultaneous three-term pre-stack elastic inversion technology, which he says enables geoscientists “to more accurately predict lithology, fluid and, most importantly, the heterogeneity of internal rock property distribution of Vp, Vs, and density. Bill Schrom, Geotrace CEO Click here to enlarge image The most significant recent technology advances in subsurface data processing are the tools for integration and data mining that are applicable through the life of the field. “If properly calibrated with other subsurface data (logs, cores, and production data), a 3D geobody ultimately can be extracted by multiple cutoff thresholds of most significant rock properties. Additionally, a static reservoir model with needed rock properties can be built for reservoir simulation and history match. When 4D or time-lapse 3D study is conducted, a dynamic reservoir can be created for optimum production.” With the advent of deepwater drilling, pore pressure estimation has become more sophisticated and has gone beyond traditional interval velocity to the compaction to pore pressure route, Schrom notes. “Geotrace’s high-density, high-resolution, high-order (HDHRHO) velocity analysis with anisotropy estimation provides the most critical 3D Interval Velocity Field (~geological velocity) at every sample and every common midpoint trace,” he says. “For example, traditionally prestack time migration estimates velocity with a ¼-mile grid that only counts for approximately 5% of data acquired and severely underutilizes the seismic acquisition investment. “Our calibrated pressure model is established with available subsurface data. It takes into account loading and offloading, burial depth, temperature, clay diagenesis, and lateral transfer and more accurately estimates HDHRHO 3D pore pressure volume, as well as other pressure attributes, such as overburden pressure, fracture gradient, and mud weights and stress for well planning and drilling hazards.” This allows engineers and drillers to plan ahead with a safety net during operation by providing an uncertainty fairway around the estimated pressure along the well path, Schrom adds. Geotrace also offers the 3D Seal Capacity Cube (a slightly less dense pore pressure volume). This tool is used for seal integrity and hydrocarbon accumulation height evaluation in the framework of prospect and regional evaluation. “The beauty of 3D pore pressure comes into play when corendering with other seismic attribute volume,” Schrom says. “Geoscientists can quickly visualize and interpret 3D pressure cells for pluming and sinks to evaluate regional drilling risk and seal concerns assessment.” Jim Sledzik, marketing director for WesternGeco, contends that “effective noise attenuation through digital group forming and 3D surface multiple attenuation has allowed us to clean the measurements in an unprecedented manner and therefore improve the quality of imaging or production monitoring in all types of environments.” Pete Bennion, vice-president, imaging, for TGS-Nopec, contends that the combination of a cost-effective computing environment using Linux cluster technology and high-speed disks has freed the software developers to enhance the precision of the algorithms and extend them while reducing turnaround. “For example, 3D SRME [surface-related multiple elimination] has become standard over 2D SRME in the past 2 years despite the considerable computational effort,” he says. “Velocity autopicking is another area where fast machines have proven effective.  Tomography has now been generalized as a velocity refinement tool for depth imaging. All-azimuth tomographic ray-tracing is now feasible and better addresses the wide-azimuth acquisition techniques now being used in 3D marine. Subsalt tomography is a reality and is being used successfully in difficult salt canopy areas of the Gulf of Mexico. Alternative multiple elimination techniques such as wavefield extrapolation are showing promise.” Davey Einarsson, CEO of Calgary-based GSI, cites SRME as a breakthrough technology: “Multiple reflections are misleading, and we finally have the technology to remove them from the data volume, resulting in ‘cleaner’ data.” Ruben Martinez, PGS chief geophysicist for data processing, cites 3D wave equation prestack depth migration (PSDM) as a key recent advance in seismic data processing: “The accuracy of the wave equation-based methods [exceed] those based on Kirchhoff implementations because wave equation methods comprehend  multivalued raypaths in the presence of complex geology and very complex velocity models.” Subsurface data interpretation While acknowledging the sophistication and power of commercial software packages for seismic interpretation, Martinez contends that advances in interpretation are mainly related to the extraction of subsurface information not obviously seen in the seismic data when analyzed in an interpretation or visualization system. “I am referring to the use of seismic attributes that can infer subsurface characteristics not seen in the conventional seismic data,” he points out. “There are many attributes that, once analyzed and combined properly, can lead to very accurate interpretations of the subsurface and its contents. For example, coherency measurements may yield maps of fracture trends. “Other advances are in the area of interpretive processing, such as acoustic impedance estimation and elastic inversion for P and S wave impedances from prestack data using [amplitude vs. offset] measurements. Maps of these estimates can be invaluable to interpret rock properties and to produce fluid content/type maps from 4D measurements.”   A great step in data interpretation came with the automatic 3D volume interpretation of geologic bodies, stratigraphic sequences, and discrete fractures after image processing and gaming industry techniques were applied to seismic data, notes Sledzik: “Also, integrated 3D visualization of subsurface measurements and interactive modeling while interpreting have helped in better understanding the data and therefore in making better decisions when guiding or correcting an automatic interpretation.” He cites WesternGeco’s i2i (interpretation to imaging) software. The software combines interpretation, processing, imaging, and specifically tomography through a permanently evolving earth velocity model. There is now a much closer linkage between interpretation and imaging driven by the need to better understand the geology, notes Bennion, citing difficult subsalt areas. “The ability to quickly view an interpretation and convert it to a new velocity model to be used in PSDM helps shorten the cycle time between generating the image and reinterpreting it,” he adds. Subsurface imaging Continuing increases in computing power are removing many of the restrictions that resulted in the use of simplified earth models in seismic imaging and inversion algorithms, Sledzik contends. “We are now seeing very impressive results when anisotropic elastic full waveform tomographic imaging and inversion algorithms are applied,” he says. “And we are really just beginning to talk about true 3D subsurface imaging with the advent of rich- and wide-azimuth marine seismic acquisition techniques, and the integration of multiple geophysical measurements (seismic, borehole, electromagnetic, gravimetric) to delineate complex geological bodies such as salt.” The dramatic increase in computing power at lower cost has also accounted for the most significant recent technology advance in subsurface imaging, contends Bennion, noting that it allows the use of multiple algorithms in depth imaging. “Kirchhoff can be used for steep dips and wide bandwidth, beam migration implementations are used for velocity model building due to their speed, wave equation is highly effective for subsalt imaging, and, finally, reverse time migration is making an appearance as today’s ultimate imaging algorithm,” he says. “Adding to this the ability to estimate and autopick anisotropy parameters epsilon and delta and run anisotropic PSDM now gives interpreters an added degree of confidence in the positioning of their prospect.” Einarsson concurs, noting that PSDM and prestack time migration “give a superior, unambiguous image of the subsurface.  The availability of relatively inexpensive, large, fast computers makes this possible.” Martinez contends that although 3D traveltime tomography is not a recent velocity estimation method, the commercialization of the method has been impressive. “Automated picking of depth residuals and dip fields has experienced important developments yielding a direct impact in turnaround time for processing very large data volumes,” he says. “Also, the accuracy and effectiveness of the ray tracing and tomographic inversion have advanced significantly in robustness and algorithmic speed.” ]

    Magazine Articles

    Magazine Articles

    Mon, 24 Sep 2007

  2. SPECIAL REPORT: Independents mitigate field costs through operating efficiencies

    Independent operators report strong US exploration and production efforts despite increased drilling costs and other service costs.

    Magazine Articles

    Magazine Articles

    Mon, 4 Feb 2008

  3. OGJ Newsletter

    drilled later. Tullow will not test the well, as it wants to assess the results of its other wells after it finishes regional drilling . Ngege-1 reached a TD of 640 m and was drilled some 3 km from the crest of the structure. Tullow said seismic interpretation

    Magazine Articles

    Magazine Articles

    Mon, 7 Jul 2008

  4. Tullow Oil makes Uganda oil, gas discovery

    Tullow Oil PLC discovered oil and gas within the Ngege-1 exploration well on the northern part of Block 2 in Uganda's Lake Albert Rift basin.

    Online Articles

    Online Articles

    Tue, 24 Jun 2008

  1. Personnel Moves and Promotions: Petrobras to undertake ADR offering, swap assets

    Magazine Articles

    Magazine Articles

    Mon, 7 Aug 2000

  2. Reed-Hycalog: US rig activity at 47-year low

    US rig activity fell to a 47-year low this summer, according to the latest census by Reed-Hycalog.

    Magazine Articles

    Magazine Articles

    Mon, 18 Oct 1999

  3. Canadian oil reserves up strongly in 2000, but gas reserves slip

    The Canadian Association of Petroleum Producers said Thursday Canada's crude oil and equivalent reserves increased 400 million bbl in 2000 to 4.8 billion. Conventional oil reserve additions, including offshore Atlantic Canada, were 131% of production in 2000.

    Online Articles

    Online Articles

    Thu, 29 Nov 2001

  4. Point of View: Apache's Harris touts firm's aggressive, 'lean and mean' drilling strategy

    Houston-based Apache Corp. experienced a 22% growth in production, 26% growth in reserves, and a 330% reserve replacement rate in 2003. It was a year in which "everything went right," said Mike Harris, Apache's director of worldwide drilling.

    Magazine Articles

    Magazine Articles

    Mon, 24 May 2004

  5. Apache's Harris touts firm's aggressive, 'lean and mean' drilling strategy

    Mike Harris Apache Corp. director, worldwide drilling "The whole deal with Apache is getting the best out of people, recognizing them as professionals, and giving them the responsibility of 15 years ago."

    Online Articles

    Online Articles

    Tue, 27 Apr 2004

  6. Drilling Market Focus: Chinese build rigs, drillers venture abroad

    China’s increasing industrialization is expanding its drilling market. The need for petroleum is driving increased drilling and Chinese yards will build more than 100 new land rigs this year.

    Magazine Articles

    Magazine Articles

    Mon, 18 Jul 2005

  7. OIL, GAS FUNDAMENTALS NEED WORK

    U.S. oil and gas producers are demonstrating industry fundamentals that the Department of Energy should watch closely. In its pursuit of a national energy strategy, DOE cannot ignore recent oil production declines. Any effective response to those declines must involve improvements to fundamentals ...

    Magazine Articles

    Magazine Articles

    Mon, 4 Jun 1990

  8. PRODUCTION RISE, CONSUMPTION FALL MAY TURN SOVIET OIL EXPORTS HIGHER

    Theodore R. Breton, John C. Blaney ICF Resources Inc. Fairfax, Va. Oil production in the Soviet republics has been falling as the Soviet Union's economy and political structure have deteriorated. The decline in Soviet oil production has accelerated in 1991, and given the current state of chaos in ...

    Magazine Articles

    Magazine Articles

    Mon, 18 Nov 1991

Get More Results
Stay Connected