BJV Design Inc.’s Post

This section is the third installment of the seismic course, focusing on marine seismic acquisition, specifically streamer data. Excuse the quality of some sketches, as drawing is not my forte. It is the concept that is important. This segment delves deeper into ghosting and its resolution methods, as well as exploring broadband seismic. Please utilize this information in discussions with seismic designers like BJV Design Inc., acquisition specialists, seismic specification companies, and others. The objective is to present the concepts rather than provide an exhaustive discourse on seismic. Special thanks to Purvi Kaspale for the graphic work. Next weeks will be delayed. It is on OBC, shear, 4D, FWI, and pore pressures. FWI, 4D, and pore pressures go together because of the interval velocities. With 4D we see changes in the pore pressures.

When a cost estimate is obtained, ensuring that the resulting seismic will satisfy the companies imaging objectives is absolutely CRITICAL. The only solution... SEISMIC SURVEY DESIGN AND MODELING must be completed PRIOR to getting a cost estimate

Tall Building Responses under Seismic Ground Motions using Perform3D

You have to know where the seismic data was actually acquired. For marine seismic data, cable feathering can be an issue – as the receivers might not be where you want them. See below. The top figure shows a green marine vessel headed north. A seismic source is off the back indicated by the red star. A single recording streamer is behind. You might think the streamer would be directly behind the vessel (dashed black line), but a current is pushing towards the east. The current angles the streamer eastward (solid black line). Farther offsets are more displaced compared to nearer offsets. One of the initial seismic processing steps involves defining accurate geometry locations. This step is important for both land and marine seismic processing. The marine example shown here is sometimes called cable feathering. How does this affect your seismic image? See the middle and bottom figures from Mladen and others, 2003. I’ve added the labels for clarity. The middle is a stacked image without cable feathering correction. The bottom is a stacked image with the corrections applied. Obviously the bottom image is preferred as more reflectors are easily noticed. There are a number of ways to ensure correct xyz locations are applied for all sources and receivers in both land and marine seismic processing. Modern 3D land and marine surveys have GPS coverage all over (and devices to help keep marine streamers in position), but nothing is fool-proof. Vintage land and marine surveys can be quite challenging to decipher exact source and receiver locations. Geometry definition is a processing step that doesn’t get much publicity, but ensuring the correct xyz positioning for all the sources and receivers is an important early step. https://lnkd.in/gNvE5maK * Interested in a seismic training class for your organization? Leave a comment or email ron.kerr@houstonseismic.com * I have online presentations introducing seismic velocities and some processing. There’s a modest cost – https://lnkd.in/gw3eQcCB #houstonseismic

Why do we shoot 3D seismic? To answer this, first a quick explanation of the difference between 2D and 3D seismic... In 2D seismic, lines are acquired one line at a time. A source line and a receiver line are laid out along a single, straight line which produces a 2-dimensional transect of the 3D earth volume. In 3D seismic, multiple lines of sources and receivers are laid out in a grid pattern. The resulting data results in a true 3-dimensional view of the subsurface. So, why do we shoot 3D seismic? Say there is a potential target and we shoot a few 2D lines. Seismic data from the 2D lines gives multiple anomalies. But with having only 2D transects, we have no idea if these anomalies are: Independent or connected structures? If we have hit the apex or edge of the 3D structure? If there are additional structures in the area? What if the actual subsurface structure has 5 independent structural anomalies? We have no idea from the 2D seismic what is happening in the subsurface in between the 2D lines. 3Ds are more expensive than 2Ds to acquire, BUT at the same time, The only way to confirm what our target structures really look like is to acquire a 3D Acquiring a 3D seismic program will significantly reduce the economic risk when compared to acquiring 2D seismic program because the complete target is mapped in 3-dimensions. Any questions, please feel free to contact us: https://lnkd.in/e4W_9bRt

When a cost estimate is obtained, ensuring that the resulting seismic will satisfy the companies imaging objectives is absolutely critical. The only solution... SEISMIC SURVEY DESIGN AND MODELING must be completed PRIOR to getting a cost estimate

Today I had a discussion with Nikita Ragozin(who is an expert in seismic cross-borehole method) about the profile of cross-hole tomography(many boreholes/pairs along one line). The profile, as it usuallly happens, is not straight, but represents a broken line.  If all boreholes pairs are inverted together (and this is very reasonable for such task), it is really significant to project SR XYZ coordinates to 2D inversion profile without distorting of SR distances.  So this idea came to my mind (highly likely not me first). Considering that the problem is 2D, everything seems to be proper and SR distances are saved for each measurement. What do you think about this?

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Discover the power of Badley's T7 Seal & other modules as well, for better (correct) interpretations and analysis! DM to SPS representative in Malaysia Mohd Nazaruddin Hamidon to arrange for an introduction and demonstration to T7 at your convenient time! #T7 #sealanalysis #interpretation #structuralgeology #BadleyGeoscience

When designing a seismic survey, the RECORDING PATCH is determined by far offset requirements. Far offset requirements are determined by looking at processing mutes, usable offset to depth ratio, and if required, critical angles. This analysis is completed on existing datasets. Seismic survey objectives will dictate the importance of the analysis. For example, determining the critical angle of the target zone for a survey to be used for structural mapping will not likely be of value. A survey to be used for lithology determination will need a full understanding of the critical angles of the target zones.