How can you geosteer horizontally to maximize reservoir contact?

In my experience at work over the years, i have come to discover that proper communication is as important as the technical knowledge of the involved personnel. There is the technology - the formation evaluation and the steering tool that enable the well to be geosteered and placed in a sweet spot within the reservoir - a given. There is also a geosteering team comprising people from different department who don't necessarily speak the same technical jargon. The well placement engineer and the subsurface team must clearly communicate where they want the well to be to the directional drilling specialist who will direct the steering tool, and he in turn must communicate clearly what is possible after evaluating the given request.

the objectives of geosteering is to maintain the proper bore hole in reservoir . The landing point in the reservoir is important. As the drilling progresses the data coming form MWD /LWD tools ae interpreted. The inclination angle, azimuth , gamma ray , sonic ray readings indicates the the position of the bit in the reserviour. effective planning at the well planning stage is important. During Drilling the formation tendencies (built or drop) once interpreted according he parameters are adjusted to stay in reserviour. Now a days tools closer to bits are installed to get readings closer to bit.

Geosteering is the technology use to steer accurately directional well to the target depth with using petrophysical and seismic data. The most important geosteering objectives and specific geological features are: 1. Maximizing contact with target pay zone 2. Avoid to drill close to the faults 3. Access to optimal reservoir exposure and minimizing non-productive zones 4. minimizing doglegs 5. Smooth drilling in the horizontal section of a directional well 6. Avoid to drill in water zone 7. Maximize reservoir contact

Focus on resistivity first. The Geosignal received will aid in determining whether the formation is less/more conductive. Based on this only(primarily and early step) further steering will be decided.

Define the geologic target and what special markers it has (GR, Resistivity, XRF signature) followed by identifying any hazard zone above or below your defined target. Generate a plan ahead of time of time around seismic data and design your plan around those risks.

W.R.T Reservoir, the geosteering is headed by the Logs (real time). If the reservoir is near a shale then GR is used. while in case of Aquifer, Resisitivity logs become more important during Geosteering the horizontal well.

Sometimes the layers are to thin (6 ft or less) and complex reservoirs with claystones/limestones/shales between sands...then a reactive method its better

Anyhow if resulted sweet zone and good oil shows its for perfect geologist and efforts otherwise due to fault, folds, uncomformitty or that ±0.5 deg more than wanted :)

The primary job of geosteering is to use a software to feed GR and resistivity log data of the nearby wells for stratigraphic correlations and indicating direction of the bed boundaries in drilled well. The second job is to integrate real time log data and compare with plan to give real time recommendations and possible scenarios ensure that the well properly positioned real time based on in planned program.

Geosteering is a critical process in the drilling of horizontal and directional wells, ensuring that the wellbore stays within the target zone to maximize production. Here are some of the best practices and methods for geosteering: Real-Time Data Collection: Utilizing tools like mud-pulse telemetry to collect real-time drilling data, including inclination and azimuth of the wellbore1. Gamma Ray Tools: The most common and basic geosteering tool, gamma ray tools provide valuable information about the lithology of the drilling area1. Resistivity Logging: Helps in identifying the location of the wellbore in relation to the target zone by measuring the resistivity of the surrounding formations.

When there is drilling out of our expection, we will call teams to discuss together geosteering data and geology information together. Be remember that it is not always correct for geosteering information. Reservoir is complicated. Because o noise, interference or calibration issues, or rock content abnormal, LWD or MWD will show strange inforation which we need to be careful to deal with it. Trust yourself or trust your experience is sometimes more important then MWD or LWD data.

Geosteering can be challenge when there is no log data in nearby wells. in heterogenous formations the real time data may different with nearby wells data may show different geological features and make impossible the integration of real time data with seismic and nearby wells petrophysical logs. also accuracy of the MWD and LWD data are essential for a successful geosteering job.

A good programming of the tools by the LWD engineers and speed of data acquisition are decisive in the complex reservoirs, ie. Colombia's land

The geosteering challenges and issues are happening during the operations specially because of unknown local geological and logs uncertainties, which are the best practices in order to improve future geosteering jobs.

Best practices includes pre-job modelling of the possible scenarios. Resistivity and Image modelling alongside GR will greately help during the realtime monitoring for any change in structure, lithology and fluid type.

Geosteering is really a good tool for geologist for drilling horizontal well. I have experienced hundreds of horizontal wells in the past twenty years. I think seimsmic is very important during drilling horizontal section. It is combined information from seismic and geosteerting informatoin in advance to determine direction next time. It could not only rely on geosteerting information.

Horizontal drilling is used for thin layer oil zones, injecting misible gas injection , or for water seeping of reservoir, like in Azadegan oil field.

The integration of RT mud loggiing, with AT/Behind bit Geosteering tools, L/MWD tools help calibrate the existing Geosteering Cross sectional model to determine in 3D where the wellbore is placed and minimize reservoir exit. The closer tools are to the bit, the smaller lag time and mudlog/show analysis sampling intervals and Proximity to Bed Boundaries sensors set in the Geosteering model all support the success of optimized reservoir exposure. This however can be especially challenging in complex carbonate lithography with rapidly changing facies and heterogeneity.

To place horizontal well in geological target layer. It requirs directional tools, LWD, geosteeing software. LWD plays vital role for either passive or reactive methods by providing real-time for immediate decision. Azmuithal gamma is the primary tool facilitate layer boundaries/dip distinguish and azmuithal resistivity as proactive tool to check lithology & geologic structure changes and maintan desired distance from bed boundaries and detect water zones for better wellbore positioning. For successful plan you should consider azmuithal LWD tools with high DOI, improved telemetry, software with forward modeling to keep geosteering always proactive.

Understanding Target Reservoir Characterization: Well planning horizontal trajectory in target reservoir should be done along rich information on target geological structure details (dip, etc ...). Monitoring Drilling Parameters: Carefull monitoring and logging drilling parametets (Torque, ROP, WOB, Gases. etc ...) plus drilling Cuttings matching expected target reservoir.

As a complement to proactive and reactive geosteering, the mechanical interaction of the appropriate bit with the right formation, will be a smooth, efficient, fast and safe performance using conservative drilling parameters. When drilling the horizontal section using an RSS, and same as a plane cruises with the nose tilted up to compensate for gravity, once the tendency of the BHA to build or drop has been verified, apply just enough force to compensate that tendency. Unless for a planned turn, maintain walk forces too, at just enough to compensate for left or right walk tendencies (cont.)

Today’s geosteering is much different from when we first started. Your geosteer person watched one well where as today their watching 2-3 sometimes 4 wells at one time. The DD needs to be more proactive and pay attention to the gamma numbers he receives from the MWD tool. Know your top and bottom inorder to help keep your motor or RSS closer to the middle of your target formation.