Low-temperature resistant and soil phase-free shielding environment-friendly killing fluid for oil and gas well workover

Abstract

The invention relates to a petroleum recovery technology, belongs to an improvement of components of a killing fluid, and particularly relates to a low-temperature resistant and soil phase-free shielding environment-friendly killing fluid for oil and gas well workover. The low-temperature resistant and soil phase-free shielding environment-friendly killing fluid contains 2-3 unit mass of a suspension agent xanthan gum XC, 2-3 unit mass of a tackifier carboxymethylcellulose sodium CMC-HV, 5-10 unit mass of a fluid loss additive carboxymethyl starch CMS, 10-400 unit mass of a reservoir shieldingagent QCX-1, 150-200 unit mass of an inorganic salt weighting agent calcium chloride, 1-3 unit mass of a surfactant, 8-10 unit mass of a corrosion inhibitor and 371-822 unit mass of medium water, wherein for the maximum mass of the calcium chloride completely dissolved by the medium water in a physical environment at a temperature of lower than or equal to normal temperature, the density of a calcium chloride aqueous solution formed by the calcium chloride and the medium water is 1.10-1.27 g/cm3 in the physical environment at normal temperature. The low-temperature resistant and soil phase-free shielding environment-friendly killing fluid provided by the invention can effectively reduce the filter loss of a system after hot rolling.

Description

technical field [0001] The invention relates to oil recovery technology, which belongs to the improvement of well killing fluid components, in particular to an environment-friendly well killing fluid with low temperature resistance and no soil phase shielding for workover of oil and gas wells. Background technique [0002] With the development of my country's petroleum industry for decades, many oil and gas fields have entered the later stage of development, the number of workovers is increasing, and the quality requirements for workovers are also increasing. According to incomplete statistics, the use of conventional well killing fluids with poor performance will cause oil and gas Well productivity generally drops by 30-50%, mainly due to foreign solid phases, which block reservoir pores and reduce productivity. Therefore, how to reduce the damage of foreign solids to the reservoir is particularly important. At present, although the solid-free killing fluid can well overcom...

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Problems solved by technology

At present, although the solid-free killing fluid can well overcome the damage of foreign solids to the reservoir, it has a large amount of fluid loss, no suspension, and the density of brine is greatly affected by climate and temperature, and t

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