Soil-phase-free strong-inhibition shielding environment-friendly well killing fluid

Abstract

The invention relates to a petroleum recovery technology, in particular to a soil-phase-free strong-inhibition shielding environment-friendly well killing fluid. The soil-phase-free strong-inhibitionshielding environment-friendly well killing fluid is prepared from X unit volume of xanthan gum XC, Y unit volume of sodium carboxymethyl cellulose CMC-HV, Z unit volume of polymer filtrate reducer SP-8, S unit volume of superfine calcium carbonate, L unit volume of carboxymethyl starch CMS, M unit volume of powdered calcium chloride and N unit volume of water, wherein X is equal to 2 to 3, Y is equal to 2 to 3, Z is equal to 0 to 2, S is equal to 50 to 100, L is equal to 0 to 10, M is equal to 300 to 400, N is equal to 482 to 646, X+Y+Z+S+L+M+N is equal to 1000, and M is smaller than or equalto the maximum mass of the powdered calcium chloride completely dissolved by the N unit volume of water in a physical environment of 15 to 25 DEG C. The soil-phase-free high-inhibition shielding environment-friendly well killing fluid can further reduce water loss (filter loss), can well overcome the liquid lock damage to reservoir caused by large filter loss, has high rheological property, can meet various well killing operations and related construction, has lower cost than a non-solid-phase well killing fluid at the same density, has low reservoir damage, has environmental protection and reservoir protection functions, and can restore the yield of an oil well to the maximum extent after completion of workover treatment.

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 without strong suppression and shielding of soil phase. 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 The production capacity of oil and gas wells generally decreases by 30-50%. The main reason is that foreign solid phases block the pores of the reservoir, resulting in a decrease in production capacity. Therefore, how to reduce the damage of foreign solids to the reservoir is particularly important. At present, although the general solid-free kill...

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Problems solved by technology

[0003] A large number of studies have shown that during the workover operation, the damage caused by the killing fluid to the oil layer is mainly due to the blockage of the rock pores by the solid phase and the change of the rock properties. Porous sub-micron soil phase particles can cause permanent damage to reservoir permeability

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