Harm-free core-drilling fluid, and its preparing method and use

Abstract

This invention discloses a kind of no damage fetching core borehole liquid and its preparation method. It is made up of the water 100000- 160000, NaCl 15000-19000, Na2CO3 200-400, NaOH 50-150, PAC-SL 150-550, FLOWZAN 200-600, Starch 1200-1800, the modified SOLTEX 1200-1800, Baracarb(5) CaCO3 a 2000-4000, Baracarb(50) CaCO3 b 2000-4000, Baracarb(600) CaCO3 c 2000-4000. The character of the no damage fetching core borehole liduid is in that: it has no damage to the core and the stratum; it has the good lubricating ability and has the good capability in cleaning well and inhibiting the drill chip disperses; the additive such as the FLOWZAN, the starch and the PAC-SL are all degraded by the organism. The Baracarb crushed by the marble is the inorganic additive and has no pollution to the environment; also it can not change the wetting property of the petrosal.

Description

technical field [0001] The invention relates to a coring drilling fluid and its preparation method and application, in particular to a non-destructive coring drilling fluid with shallow invasion depth and no impact on the environment, its preparation method and application. technical background [0002] Drilling fluid system is a complex mixture system, its composition contains alkali, inorganic salts, polymer organic polymers, the pollution to the environment is mainly manifested in high COD, high BOD, high suspended solids and pH value, oil and heavy metals salt etc. Discharge of waste drilling fluid is the main pollutant in drilling operations. If it is not controlled, it will easily lead to the enrichment of environmental pollutants and cause harm to the environment. [0003] Coring drilling fluids in foreign countries are divided into two categories: one is water-based drilling fluid; the other is oil-based drilling fluid. Defects: oil-based drilling fluid is relative...

AI Technical Summary

Problems solved by technology

[0015] 1. The modified drilling fluid system is currently widely used due to its simple process and low cost, but it is only an improvement on the basis of ordinary drilling fluid, and there is still a big gap from the goal of protecting the core

[0016] 2. The low-bentonite polymer drilling fluid system takes into account the harm of bentonite to the core, but does not consider other aspects

[0018] 4. The biggest disadvantage of the oil-in-water drilling fluid system is that it contains emulsifiers, which will change the wettability of rocks

However, the system is complex in process, requires high filtration equipment, serious leakage, and lacks suitable polymer additives in China, and there are deficiencies such as inorganic scale damage.

[0020] 6. Cationic polymer drilling and completion fluids can prevent wellbore collapse caused by clay expansion in shale and water-sensitive damage caused by clay mineral expansion in reservoirs, but the performance of the system is difficult to maintain and difficult to control

[0021] 7. Positive gel drilling and completion fluid has the ability to inhibit formation slurry, prevent well wall collapse, and has a strong ability to carry debris; Complete

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