Abstract: A method of seismic surveying and seismic data processing using a plurality of simultaneously recorded seismic-energy sources. An activation sequence for each of said plurality of seismic energy sources may be determined such that energy from seismic sources may be recorded simultaneously and seismic energy responsive to individual seismic sources separated into separate source records. The seismic sources are activated using an activation sequence, the recorded seismic energy in the shot recordings may be separated into source recordings responsive to individual seismic sources. The source records may be derived from the shot records using a combination of shot record summations, inversions and filtering.

Abstract: A portable apparatus for creating holes in rock. A rock drill connected to a compressed air supply is engaged with a connector attached between the rock drill and a rock bit. The connector has a substantially tubular shaft for transporting compressed air from the air supply to the rock bit. The tubular shaft uniquely maximizes the air available for removing rock cuttings and minimizes the possibility of rock bit sticking in the rock hole. The invention is particularly suited to seismic shothole drilling requiring portable equipment operable by a single person.

Abstract: A method of stacking seismic traces including the steps of deriving a representation of the noise component of each of the seismic traces; deriving an indication of the correlation between the noise components from the representations of the noise components, and producing a stacked seismic trace by combining the seismic traces in proportions derived from the correlation indications. The method can be used to produce stacked seismic traces having improved signal-to-noise ratios compared to conventionally stacked seismic traces. The preferred embodiment of this method is sometimes referred to as “covariant” stacking, because the weighting factors derived depend on the covariance of the noise components of their constituent traces.

Abstract: The present invention relates generally a method and apparatus for adjusting the buoyancy of towed seismic arrays comprising a plurality of streamers and specifically to the dynamic buoyancy control of the buoyancy of a towed array of streamers by means of applying current to electroactive polymers (EAP) incorporated within the towed array of seismic streamers. The bulk density of the streamer array is electrically altered to accomplish neutral buoyancy for a towed array of streamers within the full range of water-densities from fresh to extremely dense seawater.

Abstract: An apparatus for providing buoyancy to a towed marine divertor and for reducing drag acting on the divertor as the equipment is towed through water. A float attached to the divertor has a curved leading end oriented toward the tow direction to reduce water drag acting against the float. The float can be integrated within the divertor or can be attached with wire rope or chains to lower the divertor within the water. The trailing end of the float can be tapered, and vane foils can be attached to the float outboard side.

Abstract: A process for analyzing, decomposing, synthesizing and extracting seismic signal components, such as the fundamental of a pilot sweep or its harmonics, from seismic data uses a set of basis functions. The basis functions may be any of the harmonics or other components derived from the pilot sweep. These basis functions are modulated with the data being analyzed. The resulting data output from the modulation are then low-pass filtered so that the instantaneous amplitude and differential phase of the particular signal component to be synthesized may be computed. Each targeted component is then synthesized and the result subtracted from the remaining data.

Abstract: A method is disclosed for attenuating ground roll in seismic data signals. Seismic data signals are obtained from nearby seismic sensors. A difference filter is created that incorporates an estimate of ground roll differential move-out between the seismic sensors. The difference filter is then applied to the seismic data signals to produce a ground roll attenuated seismic data signal. The method can be used with one-pass and multiple-pass filter operations and can be used in connection with pairs of seismic data signals or with groups of seismic data signals from an areal pattern of nearby seismic sensors. The seismic data signals may be appropriately pre-processed and factors in addition to the ground roll differential move-out can be incorporated when creating the difference filter. The inventive method can be implemented in the time domain or in the frequency domain.

Abstract: A method of marine seismic surveying, whereby a seismic streamer is towed in a body of water while deploying three (3) sensors in close proximity to each other. In one embodiment of the invention, the first sensor generates a first signal indicative of pressure of the water, the second sensor generates a second signal indicative of vertical movement of water, and the third sensor generates a third signal indicative of vertical movement of the streamer relative to the water. A seismic signal is generated in the water and the resulting signal is detected with each of the three (3) sensors simultaneously during time intervals following the generation of the seismic signal. The second signal is combined with the third signal to generate a fourth signal that measures vertical movement of the water with noise due to streamer vibration attenuated. The first signal is combined with the fourth signal to give a signal that attenuates the ghost due to the water surface.

Abstract: A swath of marine seismic data is acquired using a plurality of receiver lines, at least two near sources and at least one far source. Lines of data corresponding to the far seismic source are augmented to produce additional lines of interpolated and/or extrapolated seismic data that are equivalent to that which would be produced by a second far source. This makes it possible to obtain fill coverage seismic data with a shorter cable length and also increases the acquisition speed relative to an acquisition method using two near and two far seismic sources.

Abstract: A system and method for deploying and retrieving streamers behind a tow vessel in a marine seismic array. Each streamer and attached lead-in cable are individually deployed and retrieved into and from the array, and are connected to adjacent lead-in cables with tag lines having a slidable latch mechanism attached to one or more ends of the tag lines. Each latch mechanism is slidable along a lead-in cable until is engages a tether head at a selected location which restricts further movement. Paravanes move the attached array transversely from the centerline of the vessel movement and retain tension on the tag lines. The system uniquely permits retrieval of a single lead-in cable and attached streamer without requiring retrieval of the entire seismic array.

Abstract: A marine seismic surveying method and apparatus are shown. The apparatus includes at least one lead-in which has two or more of the streamers connected to be towed thereby, and which comprises a load-bearing outer sheath to bear the towing forces, an electrical or electro-optical core via which control signals and electrical power are supplied to, and data signals are received from, the steamers being towed by the lead-in, and a connector device series connected in the lead-in, the connector device comprising a body member mechanically coupled between the respective portions of the load-bearing outer sheath of the lead-in on either side thereof, to transmit towing forces therebetween, and a towing attachment for mechanical connection to one of the two or more streamers.

Abstract: A method for identifying optimal seismic energy source configurations for a selected seismic survey area. Physical properties of the surface or near-surface soil or rock are assessed and are tested to determine the response of such soil to energy source characteristics and geometries. A test model for a source is generated and is projected to create a far-field seismic response model. A seismic event is initiated within the survey area to measure seismic data, and such measured data is compared against the far-field seismic response model. Differences can be assessed to permit modifications to the model, and the model can be tested for different types and configurations of seismic source energy sources.

Abstract: The present invention, in certain embodiments, discloses a method for acquiring marine seismic data using a seismic acquisition system where shot points are determined and shot records recorded. A time at which the source vessel will be substantially at a shot point position is predicted and the seismic source is activated at the shot point. The shot is recorded and the next location for recording a shot is determined. If the source vessel has passed the determined next shot point position, the seismic source is activated and a shot is recorded. If the source vessel has not reached the next shot point, a time delay is implemented until the shot point is reached. The method allows for efficient acquisition of seismic data under varying field conditions by resembling a distance based shot point determination method unless a time based acquisition method becomes more appropriate due to field conditions or other operational considerations.

Abstract: A seismic surveying method and system are disclosed. The method provides a remote display representative of the quality of the coverage of a seismic survey. The method includes progressively building up at the site of the survey a first data base of data required for said display and relating to the area being covered by the survey, concurrently transmitting the data being used to build up the first data base via satellite link to a first remote location, to build up a duplicate of the first data base at said first remote location, providing access to said first remote location for the receipt of display requests from further remote locations, and in response to such requests, processing the data of said duplicate data base to provide processed data for producing said display, and compressing said processed data and transmitting it to such a further remote location for reconstitution and display thereat.

Abstract: A seismic streamer comprises a substantially solid core having many of the main components of the streamer, namely hydrophones, electronics modules for digitising the outputs of the hydrophones, the main optical and electrical conductor bundles and Keviar strength members, embedded in it. The core also contains a large number of foam buoyancy elements. An outer skin surrounds the core, defining an annular gap around the core, and this annular gap is filled with open-celled polyurethane foam saturated with kerosene. The capsules containing the hydrophones communicate with the annular gap around the core, so that the kerosene can enter the capsules, each of which contains an open-celled polyurethane foam sheath to cushion the hydrophone. In an alternative construction, made possible by using the buoyancy elements in the core to render the core approximately neutrally buoyant in water, the outer skin and the polyurethane foam are omitted, and the core is used on its own as a solid streamer.

Abstract: In a method for inverting a seismic signal, an input seismic signal is represented as an input vector i(t) of length m+n−1, an output seismic signal is represented as an output vector o(t) of length m, and a finite impulse response filter is represented as a solution vector u(t) of length n, satisfying a convolutional equation i(t){circle around (x)}u(t)=o(t). An m×, n Toeplitz matrix T(t,&tgr;) corresponding to i(t) is calculated, satisfying a matrix equation T(t,&tgr;)·u(t)=o(t). Both sides of the matrix equation are transformed to a transform domain, to generate a transformed equation. Both sides of the transformed equation are pruned, to generate a pruned equation. The pruned equation is then solved. In one embodiment of the invention, the transformed domain is the frequency domain.

Abstract: A method of acquiring and processing seismic data involving deploying a number of seismic sensors, actuating a seismic source, receiving seismic signals produced by the seismic source using the seismic sensors, calculating offset distances (44) between the seismic source and the seismic sensors, and (42) producing spatially filtered seismic data from the received seismic signals. The inventive method may be used effectively with receiver arrays having smaller areal footprints and fewer sensors per receiver station location than conventional seismic data acquisition systems. It also allows ground roll and random noise to be effectively attenuated as the seismic data is spatially resampled or prepared for spatial resampling.

Abstract: An apparatus for shaping boreholes used in seismic operations. A drill body is attached to a drill bit and is movable in axial and rotational directions. Selective operation of the drill body causes a moveable sleeve to operate a reaming bit to extend through a drill body port and into contact with the borehole wall. A cover seals the portion of the port not covered by the reaming bit to prevent loss of a transport fluid within the drill body and to prevent drill cuttings from entering the drill body interior. The cover can be integrated within the movable sleeve or can comprise a separate component. The force exerted by the drill body against the drill bit can be proportional to the force exerted by the reaming bit against the borehole wall. The reaming bit can be operated separately or simultaneously with operation of the drill bit, and can be retracted and reset to perform another shaping operation at a different position within the borehole.