Method for determining the placement of perforations in a well casing

Claim 1

A method for determining the productivity of a well site, comprising: extracting a representative core sample of a formation of interest from the well site utilizing sponge coring techniques, the portion of the total oil that bleeds out of the core sample absorbed by the sponge utilized in sponge coring techniques; measuring the porosity of the core sample at predetermined depth increments; measuring the fraction of the core space in the core sample occupied by total oil at each of the predetermined depth increments, the total oil equal to the oil remaining in the core on the surface of the well in addition to the oil that bleeds out of the core sample upon extraction thereof, the fraction equal to the percent mobile oil; determining a Production Index to indicate the producibility of the well as a function of depth increments, the Production Index varying directly with the product of the porosity, permeability and percent mobile oil; and placing a well casing in a well that is disposed in the formation of interest and placing perforations in the well casing at selected positions determined by the Production Index such that the selected perforations are located at depths having a Production Index greater than a predetermined number along the formation of interest.

Claim 2

A method for determining the productivity of a well site, comprising: extracting a representative core sample of a formation of interest from the well site utilizing sponge coring techniques, the portion of the total oil that bleeds out of the core sample absorbed by the sponge utilized in sponge coring techniques; measuring the porosity of the core sample at predetermined depth increments; measuring the fraction of the core space in the core sample occupied by total oil at each of the predetermined depth increments, the total oil equal to the oil remaining in the core on the surface of the well in addition to the oil that bleeds out of the core sample upon extraction thereof, the fraction equal to the percent mobile oil; determining a Production Index to indicate the producibility of the well as a function of depth increments, the Production Index varying directly with the product of the porosity, permeability and percent mobile oil; and placing a well casing in a well that is disposed in the formation of interest and placing perforations in the well casing at selected positions determined by the Production Index such that the selected perforations are located at depths having a Production Index greater than a predetermined number along the formation of interest.

Claim 6

A method for determining the productivity of a well site, comprising: extracting a representative core sample of a formation of interest from the well with sponge coring techniques such that the sponge traps fluids that bleed off from the core samples; measuring the porosity of the core sample at predetermined depth increments; measuring the permeability of the core sample at each of the predetermined depth increments; measuring the oil saturation in the core sample at the predetermined depth increments, the oil saturation equal to the percent of the pore space of the core sample which is occupied by oil; measuring the percentage of oil in the pore space absorbed by the sponge at each of the predetermined depth increments; calculating the total percentage of oil saturation which is equal to the sum of the oil in the core plus the oil in the sponge as a percent of the pore space of the core sample at the predetermined depth increments; calculating percent mobile oil, the percent mobile oil equaling the fraction of the total percentage of oil saturation that is absorbed by the sponge as a percentage; calculating a core factor, the core factor equaling the square root of the product of the porosity times the permeability; calculating the Production Index, the Production Index equaling the product of the core factor and the percent mobile oil; the Production Index providing an indication of the producibility of a well, a high value for the Production Index indicating a more producible zone than a low value; placing a well casing in the well; and disposing perforations in the walls of the well casing as a function of peaks in the Production Index where the value of the Production Index is greater than a predetermined value.

Claim 7

A method for determining the productivity of a well site, comprising: extracting a representative core sample of a formation of interest from the well with sponge coring techniques such that the sponge traps fluids that bleed off from the core samples; measuring the porosity of the core sample at predetermined depth increments; measuring the permeability of the core sample at each of the predetermined depth increments; measuring the oil saturation in the core sample at the predetermined depth increments, the oil saturation equal to the percent of the pore space of the core sample which is occupied by oil; measuring the percentage of oil in the pore space absorbed by the sponge at each of the predetermined depth increments; calculating the total percentage of oil saturation which is equal to the sum of the oil in the core plus the oil in the sponge as a percent of the pore space of the core sample at the predetermined depth increments; calculating percent mobile oil, the percent mobile oil equaling the fraction of the total percentage of oil saturation that is absorbed by the sponge as a percentage; calculating a core factor, the core factor equaling the square root of the product of the porosity times the permeability; calculating the Production Index, the Production Index equaling the product of the core factor and the percent mobile oil; the Production Index providing an indication of the producibility of a well, a high value for the Production Index indicating a more producible zone than a low value; placing a well casing in the well; and disposing perforations in the walls of the well casing as a function of peaks in the Production Index where the value of the Production Index is greater than a predetermined value.

Claim 9

A method for placement of perforations in a well casing to maximize producibility in a well site, comprising: extracting a representative core sample of a formation of interest in the well; measuring the porosity of the core sample at predetermined depth increments; measuring the permeability of the core sample at each of the predetermined depth increments; measuring the fraction for the pore space in the core sample occupied by total oil at each of the predetermined depths, the total oil equal to the oil remaining in the core on the surface of the well in addition to the oil that bleeds out of the core sample upon extraction thereof, the fraction equal to the percent mobile oil; determining a Production Index to indicate the productivity of the well, the Production Index varying directly with the product of porosity, permeability and percent mobile oil and as a function of the predetermined depth increments; placing a well casing in the well; and perforating the well casing at locations determined by the Production Index such that the perforations are placed at depths having a Production Index that is greater than a predetermined value such that perforations are located proximate peaks in the value of the production index rather than valleys in the value thereof.

Claim 10

A method for placement of perforations in a well casing to maximize producibility in a well site, comprising: extracting a representative core sample of a formation of interest in the well; measuring the porosity of the core sample at predetermined depth increments; measuring the permeability of the core sample at each of the predetermined depth increments; measuring the fraction for the pore space in the core sample occupied by total oil at each of the predetermined depths, the total oil equal to the oil remaining in the core on the surface of the well in addition to the oil that bleeds out of the core sample upon extraction thereof, the fraction equal to the percent mobile oil; determining a Production Index to indicate the productivity of the well, the Production Index varying directly with the product of porosity, permeability and percent mobile oil and as a function of the predetermined depth increments; placing a well casing in the well; and perforating the well casing at locations determined by the Production Index such that the perforations are placed at depths having a Production Index that is greater than a predetermined value such that perforations are located proximate peaks in the value of the production index rather than valleys in the value thereof.

Claim 15

A method for placement of perforations in a well casing to maximize production in a well site, comprising: extracting a representative core sample of a formation of interest from the well with sponge coring techniques such that the sponge utilized in the sponge coring techniques traps fluids that bleed off from the core samples as a result of removing the core sample from a high pressure region at the depths of the well to a low pressure region at the service of the well; measuring the porosity of the core sample at predetermined depth increments along its longitudinal axis; measuring the permeability of the core sample at each of the predetermined depth increments; measuring the oil saturation in the core sample at the predetermined depths, the oil saturation equal to the percent of the pore space of the core sample which is occupied by oil; measuring the percentage of oil in the pore space absorbed by the sponge at each of the predetermined depth increments; calculating the total percentage of oil saturation which is equal to the sum of the oil in the core plus the oil in the sponge as a percent of the pore space of the core sample at the predetermined depth increments; calculating percent mobile oil, the percent mobile oil equaling the fraction of the total oil saturation that bleeds into the sponge as a percentage; calculating a core factor, the core factor equaling the square root of the product of the porosity times the permeability; calculating the Productivity Index, the Productivity Index equaling the product of the core factor and the percent mobile oil; the Production Index providing an indication of the productivity of a well, a high value for the Production Index indicating a more producible zone than a low value; placing a well casing in the well; and perforating the well casing at locations determined by the Production Index such that the perforations are placed at depths having a Production Index that is greater than a predetermined value such that perforations are located proximate peaks in the value of the Production Index rather than valleys in the value thereof.

Claim 16

A method for placement of perforations in a well casing to maximize production in a well site, comprising: extracting a representative core sample of a formation of interest from the well with sponge coring techniques such that the sponge utilized in the sponge coring techniques traps fluids that bleed off from the core samples as a result of removing the core sample from a high pressure region at the depths of the well to a low pressure region at the service of the well; measuring the porosity of the core sample at predetermined depth increments along its longitudinal axis; measuring the permeability of the core sample at each of the predetermined depth increments; measuring the oil saturation in the core sample at the predetermined depths, the oil saturation equal to the percent of the pore space of the core sample which is occupied by oil; measuring the percentage of oil in the pore space absorbed by the sponge at each of the predetermined depth increments; calculating the total percentage of oil saturation which is equal to the sum of the oil in the core plus the oil in the sponge as a percent of the pore space of the core sample at the predetermined depth increments; calculating percent mobile oil, the percent mobile oil equaling the fraction of the total oil saturation that bleeds into the sponge as a percentage; calculating a core factor, the core factor equaling the square root of the product of the porosity times the permeability; calculating the Productivity Index, the Productivity Index equaling the product of the core factor and the percent mobile oil; the Production Index providing an indication of the productivity of a well, a high value for the Production Index indicating a more producible zone than a low value; placing a well casing in the well; and perforating the well casing at locations determined by the Production Index such that the perforations are placed at depths having a Production Index that is greater than a predetermined value such that perforations are located proximate peaks in the value of the Production Index rather than valleys in the value thereof.