SOFTWARE USED IN
BEATING THE EXPLORATION SCHEDULE WITH INTEGRATED DATA INTERPRETATION:
KANSAS OIL’s EXPERIENCE: a virtual case study
• Oil companies have made great strides in improving the success rate of exploration and production
• Once a well is spudded, the company commits considerable resources to gather more data such as mud logs, cores, measurements-while-drilling (MWD) information and wireline logs.
• This creates a huge volume of data—often at different scales and qualities—that must be efficiently handled to ensure maximum return on the exploration investment.
• Integrated software packages that use acommon framework with a common dataformat and a common data base are nowavailable. These packages provide the toolsfor geoscientists to work on data simultane-ously in a user-friendly way.
• This presentation will examine a fictional scenario depicting Kansas Oil’s approach on its latest exploration well.
• Kansas Oil is a hypothetical small-to medium-sized oil company, based in Hilton, Australia.
• It has a flexible organization that allows members of different departments to form teams to work on specific projects. Its offices are equipped with work-stations linked by ethernet to a file server.
• It also rents satellite links to its drilling rigs, allowing data transfer rates of up to 128 kilobits per second, for instance between offshore locations and Kansas Oil’s offices.
• Earlier in the year, Kansas Oil commissioneda 3D seismic survey over the entire 22Bblock in George Bay, awarded to the com-pany in the 2006 Australian licensinground.
• Based on preliminary work in Hinton,thesenior geologist and the senior geophysicist,concluded that it would be worth drilling for oil.
Sandip Sarin,Reservoir analyst
Shankar Rajpal,Rock Mechanics
Well Planning Meeting
• Conversation regarding the need of the different software packages.
• The area of concerns of the exploration manager
1.How can we make sure we don’t hit gas?
2.What’s the rig going to be doing while you interpret all this stuffs?
Exploratory drilling(121/4-in. Hole and 95/8-in. Casing)
• A month later, when drilling begins, a wide variety of data is gathered.
• The mud logger collects and analyzes samples of cuttings.• MWD data, recorded to aid drilling, also help the geologists
define formation tops.• These data and lithological description are transmitted
daily from the offshore rig to Kansas Oil’s office.• There, they are loaded into a common data base assigned
to the well, allowing accessibility to every member ofthe exploration team.
Geologist Kuldeep’s workstation screen.In the foreground is the structural dipmeterinterpretation he has just made.Nirmal and Kuldeep are comparing the interpretation to the seismic section to ensure that the well will pass through the flanks of the reservoir.
Geological interpretation• Petroleum geology is principally concerned with
the evaluation of seven key elements in sedimentary basins:
• Source• Reservoir• Seal• Trap• Timing• Maturation• migration
Role of software
Geological interpretation within the GeoFrameenvironment uses a series of modules for:
• Data conversion
• Pre-interpretation processing
• Detailed analysis.
Sub modules of bore view module
• Bore hole image interpretation submodules.
• Structural interpretation.
• The sine-wave interactor graphics tool has been used to label faults (blue), bedding (green) and fractures (yellow) on an Formation MicroScanner image (center track). Alongside the dip magnitude and azimuth are calculated for each feature described by a sine wave.
• Once validated by the geologist as sensible,the final model is then displayed and oriented for comparison with, say a seismic section.
• After the first set of logs has been run andwhile the borehole imaging tool is loweredinto the well, a rapid petrophysical interpre-tation (quicklook) is run on the computer in the logging unit. The results are obtainedwithin 15 minutes and transmitted to KansasOil’s office.The quicklook identifies several oil zones.
• Back in Hinton, petrophysicist Nirmal Chandranchecks and discusses the wellsite interpretation with Kuldeep, and also starts to plan a more thorough petrophysical interpretation.
Petrophysical interpretation of wireline logsinvolves a series of modules within the
GeoFrame environment1) Quick view module2) Module for detailed interpretation grouped under
the ELANPlus module.
• The quick view module gives a rapid interpretation of open hole logs such as density, neutron porosity, gamma ray and resistivity
• Environmental correction such as hole size borehole salinity and temperature
• The petrophysical interpretation consists of 3 parts
1) Log measurements
• Similarly there are 3 mathematical problems which are solved by the software which helps in better predictions
1) Inverse problem
2) Forward problem
3) Calibration problem
Composite log from ELANplus module.
• Nirmal is to make a full petrophysical analysis within three hours— he is aided by the quicklookthat gives him an idea of which interpretation models to use.
• Meanwhile back at the rig, the hole is being reconditioned for further wire-line operations.
• “The detailed petrophysical interpretation has cut Swacross most of the interesting zones,” Nirmalexplains to exploration manager , who has a partner’s meeting pending and needs an update. “But over this particular interval, we might have extensive diagenesis and bioturbation, which may affect permeability. We’ll need to examine the borehole image and cores to confirm this.”
• Kuldeep is already acting on this information.He processes the borehole image data usingone of the workstation’s geological applications, bringing up the petrophysical interpretation for cross reference. He also helps Nirmal and Sandip plan the formation tester run. This includes picking depths where they want formation tester pressure measurements, and choosing the tool configuration to measure both horizontal and vertical permeability, to check communication between zones.
• They plan to take samples from all zones and also perform mini-hydraulic fracture operations on the oil-bearing zones for rock stress measurements.
• Following the partners’ meeting, Exploration manager gives the go-ahead. The conditioning trip winds up, and the testing and sampling are soon under way.
• Testing samples show oil and are sent to the pressure-volume-temperature (PVT) laboratory for analysis. The lab confirms that the samples are light crude oil and begins the PVT analysis—data that will be needed later for the detailed well test interpretation.
• The wireline transient pressure data are transmitted to Hinton, where Sandip begins to interpret them.
• Reservoir analysis within the GeoFrameenvironment is performed by two modules.
-The Polaris module
-Zodiac Zoned Dynamic Interpretation,Analysis and Computational module.
Polaris module interpretation of multiprobe formation tester transient pressure data.Pressure recordings from vertical and horizontal monitor probes are plotted against time(top left).Change in pressure at the vertical probe against change in pressure at the horizontal probe(top right).Reservoir parameter estimates are calculated and displayed at bottom right.Buttons(bottom left)access pop0up menus for data entry,manipulationand interpretation model choice.
Sandip’s workstation.Sandip uses the petrophysical interpretation(back-ground right)and the boreho;e image data(background left)to help analyze wireline formation tester transient pressure data(foreground).Nirmal and Kuldip use the pressure data,petrophysicalinterpretation and the boreho;e image data to decide whether the shale beds are continuous or simply lenses.
• Wireline formation testing:
Uses Polaris module
• Well testing
Uses Zodiac module.
• Throughout the initial interpretation and discussions between the geoscientists, the partners and Kansas Oil’s management are kept fully informed.
• Composite presentations are quickly displayed on workstation screens and screen dumps are sent across networks to color printers in partners’ offices formed.
• This result in speedy,cost-effective decisions on how the well should be completed and tested.
• Meanwhile Shankar has been working on the shear sonic data onto his workstation for mechanical properties studies.
• Computing rock properties such as bulk modulus,shear modulus or Poisson’s ratio.
• Predict the behavior of the formation when it is subjected to stresses caused by drilling or production.
Wellbore stability display.In this example the impact module has been used to integrate log data with core measurement to calculate maximum and minimum mud weight.Thecalculated safe mud weight range is presented in track 2.Lowe left is the cross plot showing the Mohr-Coulomb calibration used to calculate formation strenght and safe mud weight
Funtions of the module
• Works within the GeoFrame environment.
• Impact Integrated Mechanical Properties Analysis Computational Technique module.
- Impact module
- The wellbore stability application
- The sand strength application
- The hydraulic fracture application
• Soon afterward, the readings are set andthe well is tested in five promising zonespicked by our team. The best zone flowed2175 barrels per day with a wellhead pressure of 415 psi. The well was then suspended prior to the partners approving a full-fledged development plan.
Composite log(background),well test design(middle),borehole stability log(foregrounds) displayed on his screen.
Fact or Fiction?
• While Kansas Oil’s story is fictional, all the software applications used for data processingand interpretation described here are available.
• What has not been available, earlier, was the framework to link these applications so that they can share a common data base that allows input data and result updates to be coordinated automatically between different programs.
• Schlumberger’s GeoFrame software provides such a framework, allowing applications and interpretation modules to be linked and branched together under thecontrol of a process manager.
• Data management is handled by an ORACLE data base that labels and tracks every bit of information from raw input data to interpretation results.
• The system runs on UNIX-based workstations allowing several users simultaneous access to work.