Methods for investigating earth formations

Claim 2

A machine method of investigating earth formations adjoining a borehole, comprising: a. deriving measurements of the acoustic travel time of a formation over a section of a borehole; b. deriving measurements of the bulk density of the formation over the borehole section; and c. combining said measurements of travel time Delta t and bulk volume Rho b to produce indications of the bulk volume percentages Vf, Va, and Vc of fluid, ash and carbon respectively, in accordance with the matrix: Delta t Delta tfVf + Delta taVa + Delta tcVc Rho b Rho fVf + Rho aVa + Rho cVc 1 Vf + Va + Vc where Delta t and Rho f, Delta ta and Rho a, and Delta tc and Rho c are the characteristic travel times and bulk densities of the fluid, ash and carbon respectively.

Claim 3

A machine method of investigating earth formations adjoining a borehole, comprising: a. deriving measurements of the acoustic travel time of a formation over a section of a borehole; b. deriving measurements of the bulk density of the formation over the borehole section; and c. combining said measurements of travel time Delta t and bulk volume Rho b to produce indications of the bulk volume percentages Vf, Va, and Vc of fluid, ash and carbon respectively, in accordance with the matrix: Delta t Delta tfVf + Delta taVa + Delta tcVc Rho b Rho fVf + Rho aVa + Rho cVc 1 Vf + Va + Vc where Delta t and Rho f, Delta ta and Rho a, and Delta tc and Rho c are the characteristic travel times and bulk densities of the fluid, ash and carbon respectively.

Claim 4

A machine method of investigating earth formations adjoining a borehole, comprising: a. deriving measurements of the acoustic travel time of a formation over a section of a borehole; b. deriving measurements of the bulk density of the formation over the borehole section; and c. combining said measurements of travel time Delta t and bulk volume Rho b to produce indications of the bulk volume percentages Vf, Va, and Vc of fluid, ash and carbon respectively, in accordance with the matrix: Delta t Delta tfVf + Delta taVa + Delta tcVc Rho b Rho fVf + Rho aVa + Rho cVc 1 Vf + Va + Vc where Delta t and Rho f, Delta ta and Rho a, and Delta tc and Rho c are the characteristic travel times and bulk densities of the fluid, ash and carbon respectively.

Claim 5

The method of claim 1 and further including the step of combining said travel time and bulk density measurements to obtain indications of the strength or competence of formations adjoining said borehole section.

Claim 6

The method of claim 2 wherein said travel time Delta t and bulk density Rho b measurements are combined to produce indications of the dynamic Elastic Modulus of Deformation Ed in accordance with the expression Ed ( Rho b/( Delta t)2)K where K is a proportionality constant.

Claim 7

A machine method of investigating earth formations adjoining a borehole, comprising: a. deriving measurements of the acoustic travel time of a formation over a section of a borehole; b. deriving measurements of the bulk density of the formation over the borehole section; and c. deriving measurements of the hydrogen content of the formation over the borehole section; d. combining said derived measurements to obtain representations of the bulk volume percentage of formation parameters of which at least one is useful in determining the presence of coal deposits in said formation; e. monitoring at least one of the bulk volume percentage computations produced by said combining step to detect the presence of an appreciable coal deposit; and f. combining said travel time and bulk density measurements upon such an appreciable coal deposit being detected to produce indications of parameters relating to the quality of such a coal deposit.

Claim 8

A machine method of investigating earth formations adjoining a borehole, comprising: a. deriving measurements of the acoustic travel time of a formation over a section of a borehole; b. deriving measurements of the bulk density of the formation over the borehole section; and c. deriving measurements of the hydrogen content of the formation over the borehole section; d. combining said derived measurements to obtain representations of the bulk volume percentage of formation parameters of which at least one is useful in determining the presence of coal deposits in said formation; e. monitoring at least one of the bulk volume percentage computations produced by said combining step to detect the presence of an appreciable coal deposit; and f. combining said travel time and bulk density measurements upon such an appreciable coal deposit being detected to produce indications of parameters relating to the quality of such a coal deposit.

Claim 9

The method of claim 4 wherein the step of combining said travel time and bulk density measurements to produce coal quality indications includes combining said travel time Delta t and bulk density Rho b measurements to obtain indications of the volume of fluid Vf, carbon Vc, and ash Va in accordance with the matrix: Delta t Delta tfVf + Delta taa + Delta tcVc Rho b Rho fVf + Rho aVa + Rho cVc 1 Vf + Va + Vc where Delta tf, Rho f and Delta ta, Rho a and Delta tc, Rho c are the characteristic travel times and densities of fluid, ash and carbon respectively.

Claim 10

The method of claim 5 and further including the step of multiplying the fluid, ash and carbon volume indications by the factors Rho f/ Rho b, Rho a/ Rho b, and Rho c/ Rho b respectively, to obtain indications of the percent by weight of fluid, ash and carbon respectively.

Claim 11

A machine method of investigating earth formations adjoining a borehole, comprising: a. deriving measurements of the acoustic travel time Delta t of a formation over a section of a borehole; b. dEriving measurements of the bulk density Rho b of the formation over the borehole section; c. deriving measurements of the hydrogen content related porosity phi N of a formation over the borehole section; d. combining said derived measurements to obtain representations of the amounts of a plurality of formation parameters P1, P2, P3 and P4 in said formation in accordance with the matrix: Delta t Delta t1P1 + Delta t2P2 + Delta t3P3 + Delta t4P4 Rho b Rho 1P1 + Rho 2P2 + Rho 3P3 + Rho 4P4 phi N phi N1P1 + phi N2P2 + phi N3P3 + phi N4P4 1 P1 + P2 + P3 +P4 where Delta t1, Rho 1, phi N1 and Delta t2, Rho 2, phi N2 and Delta t3, Rho 3, phi N3 and Delta t 4, Rho 4, phi N4 are the characteristic travel times, densities and hydrogen content related porosities for parameters P1, P2, P3 and P4 respectively; and e. combining said travel time and density measurements to obtain representations of the amount of fluid, ash and carbon in a formation in accordance with the matrix: Delta t Delta ctfVf + Delta taVa + Delta tcVc Rho b Rho fVf + Rho aVa + Rho cVc 1 Vf + Va + Vc where Vf, Delta tf, Rho f and Va, Delta ta, Rho a and Vc, Delta tc, Rho c are the amounts, characteristic travel times and densities of fluid, ash and carbon respectively.

Claim 12

A machine method of investigating earth formations adjoining a borehole, comprising: a. deriving measurements of the acoustic travel time Delta t of a formation over a section of a borehole; b. dEriving measurements of the bulk density Rho b of the formation over the borehole section; c. deriving measurements of the hydrogen content related porosity phi N of a formation over the borehole section; d. combining said derived measurements to obtain representations of the amounts of a plurality of formation parameters P1, P2, P3 and P4 in said formation in accordance with the matrix: Delta t Delta t1P1 + Delta t2P2 + Delta t3P3 + Delta t4P4 Rho b Rho 1P1 + Rho 2P2 + Rho 3P3 + Rho 4P4 phi N phi N1P1 + phi N2P2 + phi N3P3 + phi N4P4 1 P1 + P2 + P3 +P4 where Delta t1, Rho 1, phi N1 and Delta t2, Rho 2, phi N2 and Delta t3, Rho 3, phi N3 and Delta t 4, Rho 4, phi N4 are the characteristic travel times, densities and hydrogen content related porosities for parameters P1, P2, P3 and P4 respectively; and e. combining said travel time and density measurements to obtain representations of the amount of fluid, ash and carbon in a formation in accordance with the matrix: Delta t Delta ctfVf + Delta taVa + Delta tcVc Rho b Rho fVf + Rho aVa + Rho cVc 1 Vf + Va + Vc where Vf, Delta tf, Rho f and Va, Delta ta, Rho a and Vc, Delta tc, Rho c are the amounts, characteristic travel times and densities of fluid, ash and carbon respectively.

Claim 13

The method of claim 7 and further including the step of combining said travel time and bulk density measurements to obtain the dynamic elastic modulus of deformation in accordance with the relationship Ed ( Rho b/( Delta t)2)K where K is a proportionality constant.