The Western Canadian Sedimentary Basin is a mature oil and gas area, where most of the easy reservoirs have already been discovered, and in many cases already drained. Most new plays are linked to the deployment of new technologies in reservoirs previously deemed un-economic.
Where is remote geo-steering applicable?
Not every play is suitable for remote geo-steering. Most conventional plays arenít, due to the fact that the best borehole follows the best quality reservoir, and cuttings sample observation is crucial in determining the optimal wellpath. A few of the largest resource plays drilled nowadays are prime candidates, however. Contributing factors are good well control of resource plays and existing in-depth knowledge of reservoir characteristic from previously drilled stratigraphic wells.
Most new gas wells use horizontal drilling to open up more reservoir. The same is true for heavy oil in-situ wells. Gamma markers are used for landing the build section for most horizontal wells. Not sample description, but continuously supervision and communication are the key for optimal landing.
When hydraulic fracturing jobs create large permeable conduits around the wellbore, the hole can be drilled at some distance from the best natural porosity and still tap the entire hydrocarbon potential of the reservoir. The prime objective when penetrating low permeability reservoirs with thick layers of monotonous shale or siltstone is not so much rock quality, but drilling efficiency. MWD and drilling parameters are sufficient to choose the optimal drill path in such horizontal wells. Remote geo-steering can be used to drill wells in the Horn River shale gas play or in the Montney Formation in the southern Peace River Country.
When drilling horizontal wells in thin sand beds, penetration rate is the first alarm when the bit hits roof or bottom of the reservoir. Gamma or other LWD signatures are most often used to decide steering direction. Fast decisions are crucial to maximize the exposure to hydrocarbon rich rock. Steering based on cuttings samples is ineffective in this kind of play (high penetration rates produce contaminated samples, and the lag time delays the process further). Lithology within a monotonous formation gives little to no information regarding the position of the wellbore within the uniform rock unit. Remote geo-steering can be applied in heavy oil wells drilled in the Clearwater and McMurray Formations in the Athabasca area, in the Bluesky Formation of the Peace River area, or in the Bakken light oil play in South-Eastern Saskatchewan.
What does remote geo-steering offer?
- Continuous supervision of drilling operations
- Continuous assessment of stratigraphic location of the drill bit in real time.
- Correlation of drilling, MWD and mud gas parameters throughout the wellbore and to offsetting wells.
- Use offset well information to optimally land the build section, by employing TVD logs with cross plot of offset data.
- Continuous monitoring and critical evaluation of the wellpath inclination and azimuth in relation to stratigraphic markers and porosity windows.
- Continuous communication with directional driller, proactive adjustments to ensure wellpath placement remains within the acceptable stratigraphic window.
- Proactively evaluate wellpath position in relation to existing and planned wellbores.
- Assess hole condition by monitoring drilling parameters and mud properties, paying particular attention to any indications of overpressure zones, sticky hole or lost circulation.
- Establish estimated timelines for events such as encountering critical Formation tops, casing points, entering reservoir, and reaching total depth.
- Estimate how long current bit is expected to drill, and when the next trip is expected.
- Generate detailed daily reports, to be distributed within the company and to partners as needed.
- Generate exhaustive final reports and striplogs.
Why should remote geo-steering be considered?
There are two main arguments to be made in favour of remote geo-steering: one is the lower cost and the second is the added safety.
Savings occur due to the fact that geologists work close to home, transportation and accommodation costs are eliminated. Day rates are typically lower for people working in town as compared to on-site personnel.
Safety is always a big concern for oil and gas companies. With fewer people at the wellsite, there is less exposure to hazards. Fewer vehicles on the road and a smaller ammount of logged driving hours also lower the risk of accidents.
Having a focused group of geologists following a project also increases the quality of the job, with better response and more accurate data acquisition. Better flow of information is another success factor of the remote geo-steering procedure.
How does remote geo-steering work?
Real-time data relay from the wellsite is a day to day reality and has become very robust and reliable in the past few years. Geologists can acquire continuous drilling and MWD parameters to decide the optimal steering direction in real time at any distance. Decisions can be instantly relayed to directional drillers. Geologists with extensive wellsite experience are key to the efficiency of a remote procedure system.
Cuttings samples can be collected at the wellsite using semi-automated sample catching systems that require minimal supervision; they can be prepared and described at a later time in a laboratory environment. For in-depth analyses, critical samples can be collected and preserved in geo-jars and gas samples can be harvested in iso-tubes and preserved for subsequent analyses in a specialized laboratory.
Chinook Consulting offers remote geo-steering services tailored for specific projects. Continuous remote geological supervision is offered in house (in the offices of our clients) or from our dedicated operations room.
If cuttings samples are required, our company can arrange sample preparation from wet samples and petrographic description in our offices, at the EUB or at the client.
- Saudi Aramco News, Dec 2008. Geosteering at Saudi Armaco
- World Oil, Oct 2005. CNRL/Halliburton - Real-time geosteering in heavy oil sands