# US 11,078,786 B2 · Salt mobility assessment and review technique (smart) for exploratory wells > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 11,078,786 B2 - Document ID: US11078786B2 - Status: Granted - Kind: B2 - Application number: 15/994,467 - Filed: 2018-05-31 - Published: 2019-12-05 - Granted: 2021-08-03 - Earliest claimed: 2018-05-31 - Assignees: Saudi Arabian Oil Company - Applicants: Saudi Arabian Oil Company - Inventors: Shrikant Tiwari; Opeyemi Adewuya; Jaber Al-Fayyadh; Ali Al-Mousa; Gregory Dolciani - Web page: https://patentgrep.com/patent/US11078786B2 ## CPC - E21B 45/00: Measuring the drilling time or rate of penetration - E21B 49/006: {Measuring wall stresses in the borehole} - E21B 41/0007: {for underwater installations (E21B41/005, E21B41/04, E21B41/06, E21B41/08, E21B41/10 take precedence)} - E21B 44/00: Automatic control systems specially adapted for drilling operations, i.e. self-operating systems which function to carry out or modify a drilling operation without intervention of a human operator, e.g. computer-controlled drilling systems; Systems specially adapted for monitoring a plurality of drilling variables or conditions - E21B 47/00: Survey of boreholes or wells (monitoring pressure or flow of drilling fluid E21B21/08) - G01V 1/38: specially adapted for water-covered areas (G01V1/28 takes precedence) - G01V 1/50: Analysing data - G01V 11/00: Prospecting or detecting by methods combining techniques covered by two or more of main groups G01V1/00 - G01V9/00 - G01V 20/00: Geomodelling in general - G01V 2200/16: Measure-while-drilling or logging-while-drilling - G01V 2210/66: Subsurface modeling - E21B: EARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS - G01V: GEOPHYSICS; GRAVITATIONAL MEASUREMENTS; DETECTING MASSES OR OBJECTS; TAGS (means for indicating the location of accidentally buried, e.g. snow-buried, persons A63B29/02) ## Abstract Provided are methods for drilling a well having a wellbore that extends into the earth and that encounters a salt layer. Such methods include determinations of subsurface salt mobility and salt balance load mud weight and the performance of salt mobility tests to determine salt creep and wellbore enlargement problems. A salt formation may be determined from well log data and a drilling rate. The presence of salt creep may be determined from torque generated by the drilling assembly and a hook load. The initial mud weight of a drilling fluid may be adjusted to a salt balance load mud weight (SBLMW) to mitigate or prevent salt creep during drilling. ## Claims ### Claim 1 A method for drilling a well having a wellbore extending into the earth, comprising: obtaining well log data from a logging-while-drilling (LWD) tool, wherein the well log data comprises resistivity data, gamma ray data, and sonic compression data; obtaining a drilling rate associated with drilling the well; determining, from the well log data and the drilling rate, the presence of a salt formation encountered by the wellbore; determining the presence of salt creep from a torque generated by a drilling assembly and a hook load; adjusting a mud weight of a drilling fluid, wherein determining the initial mud weight of the drilling fluid comprises determining the mud weight according to the following: ρ m = 101.94 ⁢ ⁢ ( OVB TVD ) - 386.95 ⁢ ⁢ ( ln ⁡ ( OVB ) TVD ) - ( 40.05 TVD ) where ρm is the mud weight in grams/cubic centimeter (g/cc), OVB is the overburden stress in MPa, and TVD is the true vertical depth in meters (m). ### Claim 2 (depends on 1) The method of claim 1, wherein determining, from the well log data and the drilling rate, the presence of a salt formation encountered by the wellbore comprises at least one of the following: determining that a resistivity from the resistivity data is in the range of 100 to 200 ohm-meter; determining that a gamma ray measurement of the gamma ray data is in the range of ±15 gamma-ray, American Petroleum Industry (GAPI) units; and determining that a sonic compression of the sonic compression data is in the range of 65-67 microseconds/foot (μs/ft). ### Claim 3 (depends on 1) The method of claim 1, wherein determining, from the well log data and the drilling rate, the presence of a salt formation encountered by the wellbore comprises determining a change in drilling rate at a constant applied weight on the drilling assembly. ### Claim 4 (depends on 1) The method of claim 1, comprising determining the presence of salt creep by: reversing the drilling assembly out of the wellbore; obtaining a drag from the reversing. ### Claim 5 (depends on 1) The method of claim 1, comprising determining the presence of salt creep by determining a change in dimension of a borehole of the wellbore using an acoustic caliper sensor. ### Claim 6 (depends on 1) The method of claim 1, wherein determining the presence of salt creep from a torque generated by the drilling assembly and a hook load comprises: rotating the drilling assembly; obtaining the torque generating by the rotation of the drilling assembly. ### Claim 7 (depends on 1) The method of claim 1, wherein determining the presence of salt creep from a torque generated by the drilling assembly and a hook load comprises: inserting the drilling assembly into the wellbore; determining a drag generated by inserting the drill string into the wellbore. ### Claim 8 (depends on 1) The method of claim 1, wherein adjusting the mud weight of the drilling fluid comprises: iteratively reducing the mud weight of the drilling fluid by 10 pounds-per-cubic foot (pcf) until the mud weight of the drilling fluid results in full circulation of the drilling fluid. ### Claim 9 (depends on 1) The method of claim 1, comprising determining an initial mud weight of the drilling fluid. ### Claim 10 A method for drilling a well having a wellbore extending into the earth, comprising: determining an initial mud weight of a drilling fluid; determining, from well log data and a drilling rate, the presence of a salt formation encountered by the wellbore, wherein the well log data comprises resistivity data, gamma ray data, and sonic compression data; determining the presence of salt creep from a torque generated by a drilling assembly and a hook load; and iteratively adjusting a mud weight of the drilling fluid until the drilling fluid has full circulation, wherein determining the initial mud weight of the drilling fluid comprises determining the mud weight according to the following: ρ m = 101.94 ⁢ ⁢ ( OVB TVD ) - 386.95 ⁢ ⁢ ( ln ⁡ ( OVB ) TVD ) - ( 40.05 TVD ) where ρm is the mud weight in grams/cubic centimeter (g/cc), OVB is the overburden stress in MPa, and TVD is the true vertical depth in meters (m). ### Claim 11 (depends on 10) The method of claim 10, wherein determining, from the well log data and the drilling rate, the presence of a salt formation encountered by the wellbore comprises at least one of the following: determining that a resistivity from the resistivity data is in the range of 100 to 200 ohm-meter; determining that a gamma ray measurement of the gamma ray data is in the range of ±15 gamma-ray, American Petroleum Industry (GAPI) units; and determining that a sonic compression of the sonic compression data is in the range of 65-67 microseconds/foot (μs/ft). ### Claim 12 (depends on 10) The method of claim 10, wherein determining, from the well log data and the drilling rate, the presence of a salt formation encountered by the wellbore comprises determining a change in drilling rate at a constant applied weight on the drilling assembly. ### Claim 13 (depends on 10) The method of claim 10, comprising determining the presence of salt creep by: reversing the drilling assembly out of the wellbore; obtaining a drag from the reversing. ### Claim 14 (depends on 10) The method of claim 10, comprising determining the presence of salt creep by determining a change in dimension of a borehole of the wellbore using an acoustic caliper sensor. ### Claim 15 (depends on 10) The method of claim 10, wherein iteratively adjusting a mud weight of the drilling fluid until the drilling fluid has full circulation comprises reducing the mud weight by 10 pounds-per-cubic foot (pcf) at each iteration. ### Claim 16 (depends on 10) The method of claim 10, comprising determining, from a rate of salt creep, that the mud weight of the drilling fluid exceeds a casing shoe fracture length. ### Claim 17 (depends on 16) The method of claim 16, comprising using an underreamer tool to enlarge the wellbore.