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On implementation of process fluids to abandon wells in a wide range of densities

UDK: 622.276.76.04
DOI: 10.24887/0028-2448-2017-11-122-125
Key words: density, abandonment fluid, well abandonment, corrosion activity, zinc bromide, caesic formiate
Authors: R.V. Karapetov, S.N. Mokhov, V.V. Savelev (Research and Engineering Institute, Vietsovpetro JV, the Socialist Republic Vietnam, Vungtau)

Development cycle for the oil and gas offshore fields at the closing stage provides for the obligatory well abandonment operation, conducted by the company-operator. The article generalizes Vietsovpetro experience on implementing the process solutions for offshore well abandonment: seawater, polymer-clay drilling mud and calcium chloride solution. Statistics data analysis of technical conditions for suspended/abandoned production strings for the last 10 years showed that the most corrosion activity belongs to seawater. Proportion of abandoned wells having corrosive wear signs, filled with seawater, regardless on oxygen scavenger and corrosion inhibitor additives, is 55 %. The signs of corrosive wear were identified in 45 % of wells, abandoned by polymer-clay solutions, treated with biocides and caustics. Preserving liquids based on calcium chloride mix with corrosion inhibitor additives have almost no corrosion impact on production strings material.

The authors stated main requirements to process solutions for temporary suspension/abandonment of wells on sedimentative stability and corrosion activity. It is indicated, that mostly highlighted criteria met by salt brines based on calcium bromide, formiate of potassium and caesium. Such solutions do not reveal acid properties and have low corrosion activity. For preserving liquids with density 1400–1800 kg/m3 it is recommended to use solutions of potassium formiate and calcium bromide; with density 1800–2000 kg/m3 – mixture of potassium and caesium formiate. Implementation of preserving liquid based on zinc and calcium bromides mixture is not recommended due to possible hydrogen-induced cracking of steel, referred to aggressive types of corrosive wearing.

References

1. Ivanov A.N., Bushkovskiy A.L., Karapetov R.V. et al., Development of abandonment fluid applied downhole while abandonment of offshore wells (In Russ.), Neftyanoe khozyaystvo = Oil Industry, 2010, no. 8, pp. 100–102.

2. Ivanovskiy V.N., Corrosion of downhole equipment and methods of protection (In Russ.), Inzhenernaya praktika, 2011, no. 3, pp. 18–25.

3. Ryabokon’ S.A., Tekhnologicheskie zhidkosti dlya zakanchivaniya i remonta skvazhin (Process fluids for completion and repair of wells), Krasnodar:  Publ. of NPO Burenie, 2002, 274 p.

4. Lamosov M.E., Povyshenie effektivnosti ispol’zovaniya zhidkostey dlya glusheniya i remonta skvazhin na osnove bromidov tsinka i kal’tsiya (Efficiency improvement of use of well-killing and workover fluids f on the basis of zinc bromide and calcium): thesis of candidate of technical science, Krasnodar, 2004.

5. Downs J., Experience in drilling HTHP wells in the North Sea (In Russ.), Neftegazovye tekhnologii, 2008, no. 8, pp. 57–66.

6. Patent no. 2215016 RF, MPK S09K 7/02, E21V 43/12, Process fluid for boring, completion and major repairs of oil and gas wells under abnormally high formation pressure and elevated temperature conditions, Inventors:  Natsepinskaya A.M., Fefelov Yu.V., Grebneva F.N., Tataurov V.G., Garshina O.V., Kashbiev Gaysa.

7. Ratent no. 8697611 US, High density brines for use in wellbore fluids, Inventors: Zhang H., Horton R.L., Prasek B.B., Dimataris M.L.K.

8. Ratent no. 7273832 US, Alkali metal tungstate compositions and uses thereof, Inventors: Benton W.J., Magri N.F.

9. ASM Handbook. Vol. 13C: Corrosion: Environments and Industries: edited by Cramer S.D., Covino B.S., ASM International, USA, Materials Park (OH), 2006, 1137 p.

Development cycle for the oil and gas offshore fields at the closing stage provides for the obligatory well abandonment operation, conducted by the company-operator. The article generalizes Vietsovpetro experience on implementing the process solutions for offshore well abandonment: seawater, polymer-clay drilling mud and calcium chloride solution. Statistics data analysis of technical conditions for suspended/abandoned production strings for the last 10 years showed that the most corrosion activity belongs to seawater. Proportion of abandoned wells having corrosive wear signs, filled with seawater, regardless on oxygen scavenger and corrosion inhibitor additives, is 55 %. The signs of corrosive wear were identified in 45 % of wells, abandoned by polymer-clay solutions, treated with biocides and caustics. Preserving liquids based on calcium chloride mix with corrosion inhibitor additives have almost no corrosion impact on production strings material.

The authors stated main requirements to process solutions for temporary suspension/abandonment of wells on sedimentative stability and corrosion activity. It is indicated, that mostly highlighted criteria met by salt brines based on calcium bromide, formiate of potassium and caesium. Such solutions do not reveal acid properties and have low corrosion activity. For preserving liquids with density 1400–1800 kg/m3 it is recommended to use solutions of potassium formiate and calcium bromide; with density 1800–2000 kg/m3 – mixture of potassium and caesium formiate. Implementation of preserving liquid based on zinc and calcium bromides mixture is not recommended due to possible hydrogen-induced cracking of steel, referred to aggressive types of corrosive wearing.

References

1. Ivanov A.N., Bushkovskiy A.L., Karapetov R.V. et al., Development of abandonment fluid applied downhole while abandonment of offshore wells (In Russ.), Neftyanoe khozyaystvo = Oil Industry, 2010, no. 8, pp. 100–102.

2. Ivanovskiy V.N., Corrosion of downhole equipment and methods of protection (In Russ.), Inzhenernaya praktika, 2011, no. 3, pp. 18–25.

3. Ryabokon’ S.A., Tekhnologicheskie zhidkosti dlya zakanchivaniya i remonta skvazhin (Process fluids for completion and repair of wells), Krasnodar:  Publ. of NPO Burenie, 2002, 274 p.

4. Lamosov M.E., Povyshenie effektivnosti ispol’zovaniya zhidkostey dlya glusheniya i remonta skvazhin na osnove bromidov tsinka i kal’tsiya (Efficiency improvement of use of well-killing and workover fluids f on the basis of zinc bromide and calcium): thesis of candidate of technical science, Krasnodar, 2004.

5. Downs J., Experience in drilling HTHP wells in the North Sea (In Russ.), Neftegazovye tekhnologii, 2008, no. 8, pp. 57–66.

6. Patent no. 2215016 RF, MPK S09K 7/02, E21V 43/12, Process fluid for boring, completion and major repairs of oil and gas wells under abnormally high formation pressure and elevated temperature conditions, Inventors:  Natsepinskaya A.M., Fefelov Yu.V., Grebneva F.N., Tataurov V.G., Garshina O.V., Kashbiev Gaysa.

7. Ratent no. 8697611 US, High density brines for use in wellbore fluids, Inventors: Zhang H., Horton R.L., Prasek B.B., Dimataris M.L.K.

8. Ratent no. 7273832 US, Alkali metal tungstate compositions and uses thereof, Inventors: Benton W.J., Magri N.F.

9. ASM Handbook. Vol. 13C: Corrosion: Environments and Industries: edited by Cramer S.D., Covino B.S., ASM International, USA, Materials Park (OH), 2006, 1137 p.


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