Graphic determination of interval velocity

Claim 2

In the determination of average velocity of propagation of seismic signals through a given subterranean interval by a process comprising the generation of seismic signals which are reflected from subterranean strata and the measurement of RootMean-Square velocities at the end points of said given interval, the improvement comprising in combination the determination of said average velocity by a graphical method comprising: a. constructing a plot of time of reflection arrival versus the square of the velocity of said seismic signals, b. projecting a straight line through the points on said plot which are respectively representative of the end points of said given interval, c. measuring the intersection of said straight line with the coordinate at T1 + T2, d. reading the velocity of propagation corresponding to said intersection, said velocity being the average velocity of propagation within said given interval.

Claim 3

In the determination of average velocity of propagation of seismic signals through a given subterranean interval by a process comprising the generation of seismic signals which are reflected from subterranean strata and the measurement of Root-Mean-Square velocities at the end points of said given interval, the improvement comprising: a. constructing a plot of time of reflection arrival versus the velocity of said seismic signals, b. preparing a template having curves corresponding to the general equation Vi V22 T2 - V12 T1/T2 - T1 or V12 V22 + T1m, where m V22 - V12/T2 - T1 c. shifting said template with respect to time until one of said curves passes through the point representative of the velocity propagation of said seismic signal at the beginning of said interval and also through the second point representative of the velocity of propagation of said seismic signal at the end of said given interval, d. reading, as said average velocity, the intersection of said curve with the coordinate representative of the sum of the time of entrY of said seismic signal into said given interval and the time of exit of said seismic signal from said given interval.

Claim 4

In the determination of average velocity of propagation of seismic signals through a given subterranean interval by a process comprising the generation of seismic signals which are reflected from subterranean strata and the measurement of Root-Mean-Square velocities at the end points of said given interval, the improvement comprising: a. constructing a plot of time of reflection arrival versus the velocity of said seismic signals, b. preparing a template having curves corresponding to the general equation Vi V22 T2 - V12 T1/T2 - T1 or V12 V22 + T1m, where m V22 - V12/T2 - T1 c. shifting said template with respect to time until one of said curves passes through the point representative of the velocity propagation of said seismic signal at the beginning of said interval and also through the second point representative of the velocity of propagation of said seismic signal at the end of said given interval, d. reading, as said average velocity, the intersection of said curve with the coordinate representative of the sum of the time of entrY of said seismic signal into said given interval and the time of exit of said seismic signal from said given interval.

Claim 5

A template for use in the determination of average velocity of seismic signals propagated through a given interval of subterranean formation, said template comprising a substantially transparent base having inscriptions of values of velocity increasing along one axis, values of time increasing along the second axis, and having inscriptions of a family of curves corresponding to various pairs of values of ''''a'''' in the following equation: T V2 - VL2/a(VU + VL) VU Upper velocity axis extreme VL Lower velocity axis extreme a an aribitrary positive value which determines the curvature.

Claim 6

A template for use in the determination of average velocity of seismic signals propagated through a given interval of subterranean formation, said template comprising a substantially transparent base having inscriptions of values of velocity increasing along one axis, values of time increasing along the second axis, and having inscriptions of a family of curves corresponding to various pairs of values of ''''a'''' in the following equation: T V2 - VL2/a(VU + VL) VU Upper velocity axis extreme VL Lower velocity axis extreme a an aribitrary positive value which determines the curvature.