# US 8,739,673 B2 · Perforating gun assembly and method for controlling wellbore pressure regimes during perforating > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 8,739,673 B2 - Document ID: US8739673B2 - Status: Granted - Kind: B2 - Application number: 13/610,853 - Filed: 2012-09-11 - Published: 2013-01-03 - Granted: 2014-06-03 - Earliest claimed: 2009-07-01 - Assignees: Halliburton Energy Services, Inc. - Applicants: Cam Van Le; Darren Ross Barlow; Jeffrey Alan Nelson - Inventors: Cam Van Le; Darren Ross Barlow; Jeffrey Alan Nelson - Web page: https://patentgrep.com/patent/US8739673B2 ## CPC - E21B 43/117: Shaped-charge perforators (E21B43/118 takes precedence) - E21B 43/1195: {Replacement of drilling mud; decrease of undesirable shock waves} - E21B: EARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS ## Abstract A method comprises: a. determining a configuration of a gun string, b. determining, by a computer, a pressure transient at a location in a wellbore, c. comparing the one or more pressures with the one or more pressure thresholds at the location, and d. perforating the wellbore with the gun string using the determined configuration of the gun string when the one or more pressures meet the one or more pressure thresholds at the location. The location in the wellbore has one or more pressure thresholds, and the pressure transient comprises one or more pressures. ## Claims ### Claim 1 A method comprising: a. determining a configuration of a gun string, wherein the gun string comprises: a plurality of perforating charges supported within a carrier gun body, wherein the plurality of perforating charges and the carrier gun body are configured to create a dynamic underbalance condition when the plurality of perforating charges are detonated; and a secondary pressure generator operably associated with at least one of the perforating charges, wherein the second pressure generator is configured to reduce at least one of a peak of the underbalance condition or a duration of the underbalance condition when activated; b. computing, by a computer, a pressure transient at a location in a wellbore, wherein the location has one or more pressure thresholds; wherein the one or more pressure thresholds comprise at least one of an overpressure or an underpressure that the location can experience without adverse effects, wherein the pressure transient comprises one or more pressures, and wherein the one or more pressures are based on the dynamic underbalance condition and the at least one of the reduced peak of the underbalanced condition or the reduced duration of the underbalance condition resulting from the activation of the secondary pressure generator; c. comparing the one or more pressures with the one or more pressure thresholds at the location; and d. perforating the wellbore with the gun string using the determined configuration of the gun string when the one or more pressures meet the one or more pressure thresholds at the location. ### Claim 2 (depends on 1) The method of claim 1, wherein the one or more pressures comprise at least one of: a peak pressure at a peak overbalance condition, a peak pressure at a maximum underbalance condition, a pressure at a stabilized reservoir pressure. ### Claim 3 (depends on 1) The method of claim 1, wherein the computer comprises a processor and software stored on a non-transitory computer readable medium, where the software configures the processor to perform step b. ### Claim 4 (depends on 3) The method of claim 3 further comprising: measuring one or more actual pressures during step d. using a pressure measurement device; and calibrating the software using the one or more actual pressures. ### Claim 5 (depends on 1) The method of claim 1, further comprising assembling the gun string using the determined configuration. ### Claim 6 (depends on 1) The method of claim 1, further comprising: e. redetermining the configuration of the gun string when the one or more pressures exceed the one or more pressure thresholds at the location; and f. repeating steps b. and c. ### Claim 7 (depends on 6) The method of claim 6, wherein the gun string comprises a plurality of perforating guns coupled in series, and wherein only the configuration of the perforating gun near the location is redetermined. ### Claim 8 (depends on 6) The method of claim 6, wherein steps b., c., e., and f. are performed by a computer. ### Claim 9 (depends on 6) The method of claim 6, wherein redetermining the configuration of the gun string comprises modifying at least one of: a total number of perforating charges, a number of perforating charges operably associated with the secondary pressure generator, a number of perforating charges not operably associated with the secondary pressure generator, a geometric design of the perforating charges, a spatial layout of the perforating charges along the gun string, a layout of the gun carriers along the gun string, a geometric design of the gun string, a composition of the perforating charges, a number of blank pipe sections, a location of the blank pipe sections, a timing of firing of the perforating charges, and any combination thereof. ### Claim 10 (depends on 6) The method of claim 6, wherein redetermining the configuration of the gun string comprises changing a ratio of deep-penetrating charges to big-hole charges. ### Claim 11 (depends on 10) The method of claim 10, wherein the ratio of deep-penetrating charges to big-hole charges is between about 100:1 and about 1:100. ### Claim 12 (depends on 6) The method of claim 6, wherein redetermining the configuration of the gun string comprises placing one or more additional secondary pressure generators at or near the location when one or more pressures of the pressure transient are below at least one minimum pressure threshold. ### Claim 13 (depends on 6) The method of claim 6, wherein redetermining the configuration of the gun string comprises reducing the amount of the secondary pressure generators at or near the location when one or more pressures of the pressure transient exceed at least one maximum pressure threshold. ### Claim 14 (depends on 6) The method of claim 6, wherein redetermining the configuration of the gun string comprises changing the timing of the firing of the plurality of perforating charges when the one or more pressures exceed the one or more pressure thresholds at the location. ### Claim 15 (depends on 1) The method of claim 1, wherein the location is at or near a zonal isolation device. ### Claim 16 A method comprising: a. determining a configuration of a gun string, wherein the gun string comprises: a plurality of perforating charges supported within a carrier gun body, wherein the plurality of perforating charges and the carrier gun body are configured to create a dynamic underbalance condition; and a plurality of secondary pressure generators operably associated with the plurality of perforating charges, wherein the second pressure generator is configured to reduce at least one of a peak of the underbalance condition or a duration of the underbalance condition; b. determining, by a computer, a pressure transient at a plurality of locations in a wellbore, wherein each location of the plurality of locations has at least one pressure threshold; wherein the at least one pressure threshold comprises at least one of an overpressure or an underpressure that each location of the plurality of locations can experience without an adverse effect, and wherein the pressure transient at each location of the plurality of locations comprises one or more pressures; c. comparing the one or more pressures at each location of the plurality of locations with the at least one pressure threshold at the corresponding location; and d. perforating the wellbore with the gun string using the determined configuration of the gun string when the one or more pressures at each location of the plurality of locations meet the at least one pressure threshold at each location of the plurality of locations. ### Claim 17 (depends on 16) The method of claim 16, further comprising: e. redetermining the configuration of the gun string when the one or more pressures exceed the at least one pressure threshold at any location of the plurality of locations; and f. repeating steps b. and c. ### Claim 18 (depends on 16) The method of claim 16, wherein the at least one pressure threshold varies at two or more locations of the plurality of locations. ### Claim 19 (depends on 16) The method of claim 16, wherein a distribution of the plurality of secondary pressure generators along the gun string is non-uniform. ### Claim 20 (depends on 16) The method of claim 16, wherein the pressure transient at each location of the plurality of locations varies along the gun string.