Preparation method of solid-free workover fluid resistant to polyvalent metal cations at ultrahigh temperature

Abstract

The invention discloses a preparation method of a solid-free workover fluid resistant to multivalent metal cations at ultrahigh temperature, which is characterized by comprising the following steps: slowly pouring 2-50 parts by weight of thickening agent into at least one of 1000 parts by weight of clear water and formation water under stirring at normal temperature, and then continuously stirring until the thickening agent is completely dissolved to obtain a polymer solution with tackifying performance, thereby obtaining the solid-free workover fluid resistant to multivalent metal cations at ultrahigh temperature. In the stirring process, 0.3-20 parts of an ultra-high-temperature polymer first precipitation inhibitor and 0.5-200 parts of an ultra-high-temperature polymer second precipitation inhibitor are sequentially added into a prepared thickening agent solution and stirred for 1 hour, then 0.1-10 parts of a sterilizing agent is added in the stirring process and continuously stirred to be uniform, then 0.1-10 parts of an ultra-high-temperature heat stabilizer is continuously added and uniformly mixed, and the ultra-high-temperature polymer thickening agent is obtained. Finally, 10-4000 parts of a density regulator is added, and the solid-free workover fluid which has the density of 1.01-2.50 g / cm < 3 > and resists polyvalent metal cations at the ultra-high temperature of 180-230 DEG C is obtained. The workover fluid has good ageing resistance, sand washing and lithology carrying properties and filtrate loss reduction properties at the ultra-high temperature.

Description

1. Technical field [0001] The invention relates to a preparation method of a multivalent metal cation-resistant solid-phase workover fluid under ultrahigh temperature, and belongs to the fields of petroleum exploitation, oilfield chemistry and oilfield macromolecules. 2. Background technology [0002] In oil and gas extraction, a large number of ultra-deep oil and gas wells need workover operations every year to ensure the normal production of oil and gas wells, and on-site construction must be carried out under the premise of safety and protection of oil well productivity. The well depth of ultra-deep oil and gas wells is usually above 6000m, and the bottomhole temperature is above 140°C, and the bottomhole temperature of some wells is above 180°C. In order to avoid the loss of the workover fluid, ensure the safety of the workover operation, protect the reservoir, and improve the sand-washing and lithology-carrying properties of the workover fluid, sodium carboxymethylcellu...

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Problems solved by technology

[0003]The purpose of this invention is to target at the current Fe3+, Fe2+, Al3+ , Ca2+ and Mg2+ and other multivalent metal cations seriously affect the anti-aging performance of the workover fluid at ultra-high temperature. The application of oilfield water with multivalent metal cations in the non-solid-phase viscosity-increasing workover fluid is limited. The formation water at the bottom of ultra-high temperature and ultra-deep wells generally contains high concentrations of Ca2+ and Mg 2+, Fe3+, Fe2+ and other polyvalent metal cations will make the workover fluid Viscosity is lost, which seriously weakens its sand washing lithology and fluid loss control. It provides a kind of Fe that can withstand high concentration of Fe in bottomhole formation water under the ultra-high temperature of 180℃~230℃. 3+, Fe2+, Al3+, Ca2+, and Mg2+ Polyvalent metal cations such as polyvalent metal cations still have good viscosity-increasing, sand-washing and lithology-carrying properties and fluid loss control properties in the ultra-deep well bottom environment, and the preparation method of a solid-free workover fluid that can balance the formation is characterized by At least one of cold gum, welan gum, diyou gum, rhamnosan gum, and sclerotin can be used as a thickener, and it can be used with water, containing Fe3+, Fe3+, Fe Oilfield formations of polyvalent metal cations such as 2+, Al3+, Ca2+ and Mg2+ At least one preparation in water, 2-butyne-1,4-diol HOCH2C≡CCH2OH, 3-hexyne-2,5- Diol CH3CH(OH)C≡CCH(OH)CH3, propynyl alcohol CH(OH)C≡CH, and 1-n-alkylalkyne-3 -Alcohol CmH2m+1CH(OH)C≡CH, at least one of the integer m=1~13 is the first precipitation inhibition of ultra-high temperature polymer Agent, sodium hexametaphosphate, phenanthroline, triethanolamine, trisodium citrate, tetrasodium edetate, sodium formate, potassium formate, sodium acetate, potassium acetate, sodium propionate, potassium propionate, 2- At least one of sodium hydroxypropionate and trisodium nitrilotriacetate is the second precipitation inhibitor for ultra-high temperature polymers, and the formaldehyde, malondialdehyde, succinaldehyde, glutaraldehyde, adipaldehyde, sodium trichlorophenate At least one of phenol, catechol, resorcinol, sodium disulfide carbamate and potassium disulfide carbamate is a bactericide, and sodium borohydride (NaBH4), potassium borohydride (KBH4), sodium dithionite (Na2S2O 4), potassium dithionite (K2S2O4), sodium bisulfite (NaHSO3), potassium bisulfite (KHSO3), sodium sulfite (Na2SO3), potassium sulfite ( K2SO3), sodium sulfide (Na2S), potassium sulfide (K2S), At least one of thiourea, o-xylene thiourea, isopropanol, n-propanol, isobutanol, n-butanol, isoamyl alcohol, n-pentanol, isohexanol and n-hexanol is an ultra-high temperature heat stabilizer, and Sodium chloride (NaCl), potassium chloride (KCl), calcium chloride (CaCl2), sodium bromide (NaBr), potassium bromide (KBr), calcium bromide (CaBr2) and at least one of zinc bromide is a density regulator

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