# US 10,501,676 B2 · Method for drilling a wellbore with a weighted hydrogen sulfide scavenger fluid

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- Number: US 10,501,676 B2
- Document ID: US10501676B2
- Status: Granted
- Kind: B2
- Application number: 16/359,129
- Filed: 2019-03-20
- Published: 2019-07-18
- Granted: 2019-12-10
- Earliest claimed: 2017-10-04
- Assignees: King Fadh University of Petroleum and Minerals
- Applicants: King Fahd University of Petroleum and Minerals
- Inventors: Salah El-Din Elkatatny; Reyad Awwad Shawabkeh; Mohamed Ahmed Nasr El-Din Mahmoud
- Web page: https://patentgrep.com/patent/US10501676B2

## CPC

- C09K 8/08: containing natural organic compounds, e.g. polysaccharides, or derivatives thereof
- C09K 8/032: {Inorganic additives}
- C09K 8/16: characterised by the inorganic compounds other than clay
- C09K 8/532: Sulfur
- E21B 21/003: {Means for stopping loss of drilling fluid (plastering the borehole wall E21B33/138)}
- E21B 41/02: in situ inhibition of corrosion in boreholes or wells
- C09K 2208/20: Hydrogen sulfide elimination
- E21B 21/062: {by mixing components}
- E21B 43/26: by forming crevices or fractures
- C09K: MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
- E21B: EARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS

## Abstract

A drilling fluid composition comprising an aqueous base fluid, a viscosifier, and a H2S scavenger comprising copper nitrate, wherein the drilling fluid composition has a H2S sorption capacity from about 4.0 to about 6.0 gram per one milliliter of the drilling fluid composition; and a method of drilling a subterranean geological formation using thereof are provided. Various embodiments of the drilling fluid composition and the method are also provided.

## Claims

### Claim 1

A method of drilling a wellbore with a weighted H2S scavenger fluid, comprising:
driving a drill bit to form the wellbore into a subterranean geological formation thereby producing a formation fluid that contains H2S; and
injecting a drilling fluid composition into the subterranean geological formation through the wellbore,
wherein the drilling fluid composition comprises
an aqueous base fluid,
a weighting agent in an amount of from 5 wt % to 15 wt % based on the total weight of the drilling fluid composition,
a viscosifier in an amount of from 0.5 to 5.0 wt %, based on the total weight of the drilling fluid composition, and
a H2S scavenger consisting of copper nitrate, and
wherein copper nitrate present in the drilling fluid composition reacts with H2S present in the formation fluid to form copper sulfide;
recovering the copper sulfide from the drilling fluid composition; and
treating the copper sulfide with nitric acid to regenerate copper nitrate while concurrently forming elemental sulfur.

### Claim 2 (depends on 1)

The method of claim 1, wherein the wellbore is a horizontal or a multilateral wellbore.

### Claim 3 (depends on 1)

The method of claim 1, wherein a temperature of the wellbore ranges from 50 to 200° C.

### Claim 4 (depends on 1)

The method of claim 1,
wherein the wellbore contains a casing that is made of at least one metal selected from the group consisting of stainless steel, aluminum, and titanium, the casing is exposed to a gaseous mixture containing up to 12 vol % of H2S, and
wherein a corrosion rate of the casing is no more than 0.0006 lb/ft2 after 6 hours of contacting with the drilling fluid composition.

### Claim 5 (depends on 4)

The method of claim 4, wherein the corrosion rate of the casing is no more than 0.00084 lb/ft2 after 24 hours of contacting with the drilling fluid composition.

### Claim 6 (depends on 1)

The method of claim 1,
wherein the formation fluid is produced for at least 1 hour but no more than 4 hours, and
wherein a concentration of H2S in the formation fluid is no more than 40 ppm.

### Claim 7 (depends on 1)

The method of claim 1, further comprising:
circulating the drilling fluid composition within the wellbore for at least 30 minutes but no more than 3 hours, after the injecting.