New reservoir engineering observations have led to the conclusion that time-lapse geophysics must be based on the understanding of the physics of fluid-filled, parallel, compliant, fractures/micro-cracks, dilating or compacting as the reservoir is produced.
When a reservoir, any reservoir, is put under production, fluid compositions change, for example oil may be partially replaced by water or gas, gas may be expelled from oil, and so on.
Of additional significance is the fact that fluid pressures drop, changing the internal stresses on the reservoir rock.
Several studies have shown that the hydraulic conductivities of faults and fractures in reservoirs can be influenced by geomechanical perturbations due to production operations.
It is reasonable to anticipate that such dynamic permeabilities will be manifest as changes in flow-rates at production and injection wells.
These reservoir engineering observations lead to the conclusion that time-lapse geophysics (observations of any reservoirs over time) must be based on the understanding of the physics of fluid-filled, parallel, compliant, fractures/micro-cracks, dilating or compacting as the reservoir is produced.
This physics has been documented over many years, based on understanding and observing the effects of closely-spaced stress-aligned fluid-saturated microcracks on seismic shear-wave splitting (SWS) in the crust and upper mantle.
Critically, seismic observations of P-wave propagation and P-waves are relatively insensitive to fluid-saturated microcracks, whereas SWS is wholly determined by parallel microcracks and can be measured with first-order accuracy.
Thus SWS is a second-order quantity (small changes in shear-wave velocities) that can be read with first-order accuracy- thus there is tremendous resolution.
Consequently, there are significant implications for geophysical, especially seismic, monitoring of reservoir dynamics.
We can say that conventional 4D seismic, towed streamer surveys for example, only discern changes in P-wave reflectivity and thus offer at best an incomplete view of reservoir dynamics, one that is unquantifiable, allowing only empirical comparisons.
Secondly, a complete, quantifiable, view of reservoir dynamics requires 3C seismic acquisition (and strengthens the case for permanent installations).
Is it time for a new geophysics?
Many people don’t realize that the oil and gas industry is one of the safest in the world. That’s why it’s important to recognize that Finding Petroleum not only conducted an offshore safety conference on May 22nd, but that videos from that conference are now available online.
The presentations include:
Martin Shaw, managing director Marine Operations and Assurance Management Solutions Ltd and ex VP technical, fleet manager and vetting service manager, BP Shipping, talking about the dangers of “procedure overload” and how it can be mitigated.
Taf Powell, Adviser, Offshore Regulation with the European Commission and ex director of HSE’s Offshore Division, speaking about the European Commissions plans and regulating offshore safety across Europe.
Steve Prast – Founder and Managing Partner of EOS Solutions, speaking about how to use 3D simulation models, based on real engineering drawings, for training and testing how real people would behave in a specific situation such as a rig evacuation, and possible injuries which might occur.
Mike Hogan, senior consultant with Link Associates and ex head of global PR with Shell, talking about how staff can be better prepared for a crisis, particularly in dealing with journalists, and why telling the truth is always the best idea.
Enhanced Oil Recovery (EOR), or increasing the amount of crude oil that can be extracted from an oil field is something that Shell believes won’t be an afterthought in the future. Reservoir engineers will plan for EOR covering the entire lifecycle of a field.
An article in OilVoice this week details Shell’s belief that it may be possible to increase recovery on a typical reservoir to as high as 70 per cent, using a mixture of advanced enhanced oil recovery techniques, together with careful field management.
“Historically, EOR was what you thought about when there was nothing else to do,” said Val Brock, Manager Improved Oil Recovery (IOR) and Enhanced Oil Recovery (EOR) with Shell.
“But we are really pushing a lifecycle view of a field – where you plan from the start how you will keep the field running.”
In the future, production from an oilfield could be enhanced using a range of different technologies during its lifetime. This mature field management can also include smart (digital) surveillance, and more sophisticated wells and reservoir management.
“It’s about how we manage a flood overall, but we also want to get to a molecular scale of understanding what is happening between the brine, the oil, and the rock so we can do that even better,’ he said. You will also need systems which can manage the enormous amounts of data, something which is currently proving very difficult,” Brock said.
“There’s no one answer. Every reservoir has a unique challenge. EOR can be the right answer, provided it’s the right EOR.”
Nigeria expects to renew onshore oil licenses with U.S. firm Chevron and Royal Dutch Shell by June, its oil minister said on Tuesday, following Exxon Mobil’s renewal in February worth trillions of dollars.
Shell, the biggest operator in Nigeria, has onshore assets that can produce 1 million barrels of crude oil per day. It is partnered in these projects by Nigeria’s state-oil firm NNPC, Italy’s Eni and France’s Total.
“In order to show our commitment to a vibrant upstream sector … we have started the renewal of leases in good faith … renewals with Chevron and Shell are expected to be concluded by June at the latest,” Diezani Alison-Madueke said in the capital Abuja.
Several onshore drilling licenses that expired as far back as 2008 have been in negotiations between foreign oil majors, Nigeria’s state-oil firm and government for years.
Exxon signed 20-year oil license renewals on Nigerian assets producing around 550,000 barrels per day in February.
The Nigerian government has been reluctant to sign new deals or renew old ones until the Petroleum Industry Bill (PIB), which is likely to increase royalties and taxes, becomes law.
In a job satisfaction survey of visitors to the Houston Offshore Technology Conference (OTC), only 42 per cent said they were ‘satisfied’ with their current positions.
The survey was carried about by OilCareers.com.
33 % of respondents felt that they could be persuaded to change jobs and 25 % claimed to be actively looking for work.
‘We expected to find a lot of job seekers at OTC this year, but we are surprised at the number of respondents who claimed that they would consider a move if another role provided better prospects,” says Mark Guest, managing director of OilCareers.com.
The energy industry is booming and is one of the foremost employers in the world. Geoscientists have a unique advantage in that they can offer their skill set in a variety of positions throughout the industry. Go out there and get that job you want!
Many of our blogs focus on traditional relationships to geophysics. One of the most important, yet not as well-known avenues that a geoscientist can work in is water-specifically cleaning it, disposing of it when it can’t be cleaned and in general, ensuring that neighboring communities are provided water safe from contamination.
OilVoice recently met with Keith Schaefer, Publisher of the Oil & Gas Investment Bulletin to discuss the topic of water, and how it applies and is important to the oil and gas industry.
The work of marine seismic survey companies is becoming more and more critical as the world’s recoverable oil and gas reserves continue to be a concern. The search for new carbon deposits ranges farther and farther offshore, and deeper and deeper beneath the surface, often in harsh, inhospitable climates. According to most estimates, seismic activity is expected to grow 10 percent this year with business picking up in the Gulf of Mexico and the Arctic continuing to be a hot exploration frontier.
“There are an estimated 380 billion barrels of undiscovered oil and gas north of the Arctic Circle that remain to be found, of which 84 percent is expected to occur in offshore areas,” says Peter Zickerman, Executive Vice President and Head of Strategic Investments for seismic explorer Polarcus in Dubai. “Until the world finds alternative energy sources, the quest to find new oil reserves and maximize extraction from existing fields remains paramount.”
Places like the Gulf of Mexico and Northwest Europe, which have been explored several times over, require companies to constantly fine-tune their data-gathering techniques to find hydrocarbons through deeper and more complex geology. “Planning starts with geological objectives,” explains Zickerman, “and the right plan provides the geological solution, not just the technology itself, and that’s been our breakthrough.”
The growth of unconventional exploration is having a huge impact on the oil and gas industry on land and at sea. These unconventional reserves, characterized by tight shale rock, are challenging for producers and have only recently become economically viable with the advent of horizontal drilling and hydraulic fracturing.
MicroSeismic, Inc.’s Mike Mueller, Vice President of Analysis, said, “There are tremendous unconventional oil and gas resources being developed onshore all over North America and internationally. Offshore unconventional resources are also plentiful but present an additional development challenge in that they tend to be in very deep water.”
The unconventional geologic opportunity is called the Lower Tertiary or Paleogene Trend (largely sandstone), characterized by tight reservoirs which have to be stimulated by injecting fluids and propellants in order to open up oil and gas flow – the fracing process. In an offshore drilling scenario, vertical wells could be drilled in 5,000 feet of water through 20,000 feet of sediment and salt and into a pre-salt interval, where stimulating in the pre-salt could begin.
“Early exploration in the Paleogene Trend in the Gulf of Mexico indicates it may contain more oil in one place than has been discovered in all other Gulf of Mexico exploration and production activities to date,” says Mueller. “And operators active in the Paleogene will need multistage hydraulic fracturing to complete wells and achieve production rates that make the fields economical in the face of increasing exploration and development costs that are in the tens of billions of dollars. In this emerging market, operators are turning to hydraulic frac monitoring to protect their investment and provide feedback on the effectiveness of their frac programs.”
MicroSeismic pioneered a method of monitoring using an array of cables containing geophones, which establishes a large two-dimensional listening device. The passive seismic data gathered 24/7 is critical to measuring pressure and stress changes and borehole failures, which can be transmitted back to an onshore office for analysis. The results are made securely available to clients anywhere in as little as five minutes. “In the hydraulic fracturing monitoring market, the systems MicroSeismic deploys are distinct from the legacy downhole technology and can be implemented offshore with existing seismic acquisition technology,” Mueller explained. The company has been testing the technology in an offshore installation for BP in Norway for the past 10 years.
In the post-Macondo era, Mueller advocates passive seismic technology as new areas of exploration and development open up and new environmental regulations take hold. “The unconventional revolution is a game-changing, 25-to-50-year process. In the U.S., the need for oil import volumes is going down. We’re reversing a trend that has been in place for 30 years or more. It’s astonishing.” And it all begins with a seismic survey.
University of Colorado Boulder Professor John Wahr of the physics department has been elected a member of the National Academy of Sciences, a top honor recognizing scientists and engineers for their distinguished and continuing achievements in original research.
Wahr, who also is a fellow of the Cooperative Institute for Research in Environmental Sciences, is an expert on theoretical geophysics and on the use of satellite measurements to better understand the planet and its atmosphere. In recent years he has been using NASA’s GRACE satellite system to measure the depletion of water and ice stored in Earth’s glaciers, ice caps, ice sheets, soils and aquifers.
In February Wahr co-led a high-profile study using GRACE to measure mass loss in global glaciers, ice caps and ice sheets during the past decade and the resulting contribution to sea level rise. Wahr also is a leading authority on the study of Earth’s rotation, Earth and ocean tides, and crustal deformation.
“This is one of the highest honors a faculty member can receive, and we are proud to congratulate Professor Wahr,” said CU-Boulder Chancellor Philip P. DiStefano. “He joins a select group of faculty from across the country who have been elected to the prestigious academy and who are relied upon to provide expert advice to our top government leaders on science and technology issues.”
Wahr, a Professor of Distinction in the College of Arts and Sciences, joined the CU-Boulder faculty in 1983. He is an elected fellow of the American Geophysical Union and has published 170 peer-reviewed journal articles in geophysics.
Recent photographs of the Antarctic Peninsula reveal a glittering landscape of ice and snow, crowned by rugged mountains rising majestically in the distance. Yet no human captured the stunning view — it was the work of machines.
Thanks to the combined technological powers of satellites and weather stations scattered around the Antarctic Peninsula, researchers can now keep tabs on the region’s shifting ice — which in recent years has undergone dramatic changes — from the comfort of their offices.
AMIGOS 6, one of many specialized weather stations staked around the region, took the image on April 24 and relayed it to a satellite the same day.
First deployed during the 2010-2011 Antarctic field season, each AMIGOS (Automated Met-Ice-Geophysics Observation System) station is equipped with a thermometer, instruments to measure wind speed and direction and a camera to photograph its surroundings. Stations set out on the ice itself are equipped with GPS to monitor changes in the flow speed of Antarctic glaciers, which are essentially huge rivers of ice.
Poland may be able to extract 25-75 billion cubic meters (bcm) of shale gas from just three coastal license areas in Western Pomerania (Slawno, Slupsk, Starogard) operated by Saponis Investments, according to a study carried out by RPS Energy.
The total deposits have been estimated at 128 bcm in the most pessimistic scenario and at 376 bcm in the most optimistic one, with recoverable resources at 25 to 75 bcm respectively.
If the estimates could be extrapolated to the country level, Poland could be sitting on conditional resources of 4.6 to 13.6 trillion cubic meters of shale gas, or recoverable resources of 1 to 3 trillion cubic meters, much above the recent estimates of the Polish Geological Institute (PIG).