CN-121991660-A - Tetrapolymer type multifunctional oil well cement fluid loss additive and preparation method thereof

CN121991660ACN 121991660 ACN121991660 ACN 121991660ACN-121991660-A

Abstract

A quadripolymer multifunctional oil well cement fluid loss agent relates to the field of oil well cementation, and solves the problems that the conventional fluid loss agent has low Wen Jingchao retarding and thickening time in the use of medium-high temperature conventional and unconventional horizontal wells, the viscosity of high Wen Jingshui slurry is too high, and abnormal gelation is difficult to ensure the well cementation quality. The cement fluid loss agent comprises, by weight, 15-42 parts of inorganic salt, 0.1-1 part of a dispersion stabilizer, 0.49-16 parts of an anionic monomer, 2.69-29 parts of a nonionic monomer, 0-9.6 parts of inorganic mineral or biological organic matters and 100 parts of deionized water, wherein the preparation method comprises the steps of weighing the inorganic salt according to a proportion, putting the inorganic salt into a reactor, adding deionized water and the dispersion stabilizer, pouring the anionic monomer and the nonionic monomer into the reactor for stirring, adding the inorganic mineral or the biological organic matters to enable the solid content of the active monomer in the solution to be 7-42wt%, and adding an initiator for copolymerization to obtain the product.

Inventors

LIU XIN
WANG JUNJIE
XIA MENGYING
ZHANG ZHENHUA
LIN RONGZHUANG
YANG XIUTIAN
HOU LIWEI
WANG GUANGLEI
JIANG TAO
MA JIAWEN
WANG HAIMIAO

Assignees

大庆钻探工程有限公司
中国石油天然气集团有限公司

Dates

Publication Date: 20260508
Application Date: 20250718

Claims (11)

1. A quadripolymer multifunctional oil well cement fluid loss agent is characterized in that: The composite material consists of the following components in parts by weight: 15-42 parts of inorganic salt, 0.1-1 part of dispersion stabilizer, 0.49-16 parts of anionic monomer, 2.69-29 parts of nonionic monomer, 0-9.6 parts of inorganic mineral or biological organic matter and 100 parts of deionized water.
2. The tetrapolymer type multifunctional oil well cement fluid loss additive according to claim 1, wherein the inorganic salt is at least one of potassium chloride, sodium chloride, ammonium chloride, potassium sulfate, sodium sulfate and ammonium sulfate.
3. The quadripolymer multifunctional oil well cement fluid loss additive of claim 1, wherein the dispersion stabilizer is a cationic polymer or nonionic polymer with a molecular weight of 10-150 ten thousand.
4. The tetrapolymer type multifunctional oil well cement fluid loss additive according to claim 3, wherein the cationic polymer is at least one of poly (dimethyl diallyl ammonium chloride), poly (acryloyloxyethyl trimethyl ammonium chloride) and poly (methacryloyloxyethyl trimethyl ammonium chloride); the nonionic polymer is at least one of polyvinyl alcohol and polyvinylpyrrolidone.
5. The quadripolymer multifunctional oil well cement fluid loss additive of claim 1, wherein the anionic monomer is at least one of AMPS, acrylic acid, styrene sulfonate, vinyl sulfonate, methacrylic acid, fumaric acid and itaconic acid; The nonionic monomer is at least one of acrylamide, N-dimethylacrylamide and NVP.
6. The quadripolymer multifunctional oil well cement fluid loss additive according to claim 1, wherein the inorganic mineral is a common mineral or a partially hydrophobically modified mineral, and the median particle size range is 0.1-300 microns; The biological organic matter is at least one of lignosulfonate, cellulose derivative, starch derivative and xanthan gum derivative.
7. The quadripolymer-based multifunctional oil well cement fluid loss additive of claim 6, wherein the hydrophobically modified mineral is hydrophobically modified fly ash; The preparation method of the hydrophobically modified fly ash comprises the steps of screening and pretreating the fly ash by using an 80-mesh screen to remove impurities in the fly ash to obtain the fly ash with the particle size of less than 150 mu m, placing the pretreated fly ash in a 105 ℃ oven for drying 4h, taking long-chain acyl chloride as a hydrophobe and absolute ethyl alcohol as a solvent, carrying out hydrophobic modification on the fly ash by adopting an esterification method, centrifuging after the reaction is finished, taking a lower-layer precipitate, dispersing and centrifuging again by using the absolute ethyl alcohol, repeating for 2-3 times, and taking the lower-layer precipitate for drying for standby; The long-chain acyl chloride is at least one of lauroyl chloride, myristoyl chloride, palmitoyl chloride and stearoyl chloride, the dosage of the long-chain acyl chloride is 5-50 wt% of that of the fly ash, the esterification reaction temperature is 60-80 ℃, and the esterification reaction time is 12-24h.
8. A method for preparing the quadripolymer multifunctional oil well cement fluid loss additive according to any one of claims 1 to 7, which is characterized by comprising the following steps: according to the mass ratio, 15-42 parts of inorganic salt is weighed and put into a reactor, 100 parts of deionized water is added, and the mixture is stirred uniformly; Weighing 0.1-1 part of cationic polymer or nonionic polymer with molecular weight of 10-150 ten thousand as dispersion stabilizer, adding into a reactor, and stirring uniformly; Weighing 0.49-16 parts of anionic monomer and 2.69-29 parts of nonionic monomer, pouring into a reactor, and uniformly stirring; weighing 0-9.6 parts of inorganic mineral or biological organic matters, pouring into a reactor, uniformly stirring, and regulating the pH value to 6-7; Adding deionized water to make the solid content of active monomer in the solution be 7-42wt%, then adding initiator whose mass is 0.1-5% of that of active monomer to make free radical copolymerization so as to obtain the invented product.
9. The method according to claim 8, wherein the mass ratio of the anionic monomer to the nonionic monomer is 1:1 to 1:10; The initiator is at least one of persulfates, hydrogen peroxide or water-soluble azo initiators.
10. The process according to claim 8, wherein the pH is adjusted to 6-7 by adding sodium hydroxide.
11. The method of claim 8, wherein the free radical copolymerization reaction temperature is 30-60 ℃ and the polymerization time is 4-16 hours.

Description

Tetrapolymer type multifunctional oil well cement fluid loss additive and preparation method thereof Technical Field The invention relates to the field of well cementation of oil wells, in particular to a quadripolymer multifunctional oil well cement fluid loss agent and a preparation method thereof. Background With the development and utilization of global unconventional oil and gas resources gradually increasing, medium-high maturity shale oil and compact oil become strategic take over resources with the highest potential in the petroleum industry. In recent years, shale oil development enters a high-speed development stage, horizontal well and large-scale volume fracturing are effective means for improving shale oil yield, and horizontal well horizontal section well cementation quality is one of key factors for ensuring large-scale volume fracturing effect. These unconventional oil and gas resource reservoirs often have complex geological environments such as low permeability, high stress, high temperature and high pressure, so that more technical problems need to be solved in the well cementation process. The oil well cement fluid loss agent plays a vital role in well cementation operation, when cement slurry passes through permeable stratum in well cementation process, water in the cement slurry can flow out to stratum, if the water loss of the cement slurry is not well controlled, cement slurry cement ratio is low, cement particles are not hydrated sufficiently, cement stone structure is loose, even bridge is formed, annular fluid channeling is caused, interlayer packing is failed, and well cementation quality is seriously affected. The existing fluid loss agent products have the common defects of tackifying and flocculating, the problems of overhigh cement paste consistency, thickening reversion and super retarding are extremely easy to occur in the range of 80-90 ℃, and the hydration difference of the oil well cement can induce the deterioration of the fluid loss agent at 100-120 ℃ so as to degrade or decompose water-soluble groups and adsorption groups on the molecular structure of the fluid loss agent, thereby not only reducing the capability of controlling free water, but also possibly affecting the thickening performance of the oil well cement, causing the phenomena of core-spun and temperature inversion and threatening the construction safety and the cementing quality. The addition amount of the cement paste in a cement paste system is limited for the purpose of ensuring construction safety, so that the system is dehydrated, and the cementing requirements of a horizontal well, a shale oil well and the like are difficult to meet. The problems of overlarge performance allowance, easy occurrence of super retarding and slow low-temperature strength development of the high-temperature resistant product, high cost and important consideration of molecular structural design is physical and chemical reaction with oil well cement at ultrahigh temperature, and the measures do not completely play roles on the oil well cement in a medium-high temperature region. In summary, the conventional oil well cement fluid loss agent still has certain defects under the medium and high temperature conditions, particularly has the problems of super retarding and thickening reversion easily caused by low Wen Jingji when the conventional oil well cement fluid loss agent is used in a horizontal well at the medium and high temperature (80-120 ℃), has poor sedimentation stability when the conventional oil well cement fluid loss agent is used in a high-temperature well, is not easy to ash after being matched with a stabilizer, has the problems of thick slurry at low temperature and thick slurry and high temperature dilution, and is unfavorable for stable cement slurry performance and improvement of well cementation quality. Disclosure of Invention The invention provides a quadripolymer multifunctional oil well cement fluid loss agent, which aims at solving the problems that the conventional fluid loss agent in the background art has low Wen Jingchao retarding and thickening time reversal, high Wen Jingshui slurry viscosity is too high and abnormal gelation is difficult to ensure the well cementation quality in the use of medium-high temperature conventional and unconventional horizontal wells. The quadripolymer multifunctional oil well cement fluid loss agent has wide application temperature range, has weak retarding and dispersing effects on the basis of good temperature resistance, time delay and fluid loss control effects, can meet the performance requirements of a 80-120 ℃ horizontal well on thickening, rheological property and the like of cement paste without retarder and dispersing agent, realizes multiple effects of one agent, and effectively reduces cost. The invention also provides a preparation method of the quadripolymer multifunctional oil well cement fluid loss additive. The invention solves the problems by the f