Retarded acid system

A retarding acid and system technology, applied in drilling compositions, chemical instruments and methods, etc., can solve the problems of large formation damage and limited retardation effect, meet the requirements of low damage, improve retardation effect, and small molecular weight Effect

Inactive Publication Date: 2019-12-13
SOUTHWEST PETROLEUM UNIV
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  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0006] The object of the present invention aims at the technical problem that the existing retarding acid system has limited retarding effect and great damage to the formation, and provides a retarding acid system with good retarding effect, low molecular weight and low damage

Method used

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Examples

Experimental program
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Effect test

Embodiment 1

[0022] Analysis on the Interaction Mechanism of Cationic Surfactant Alkyltrimethylammonium Chloride and Rock

[0023] Since the molecules of quaternary ammonium salt surfactants with different carbon chain lengths belong to homologues, the interaction mechanism with rocks (taking calcite as an example) is similar. Here, tetradecyltrimethylammonium chloride (C for short) 14 TAC) as an example for analysis.

[0024] N atom as C 14 The head group atom of TAC does not have the conditions to participate in chemical bonding. First, from the analysis of the spatial structure of the N atom, the N atom is surrounded by four methyl substituents, and it is impossible to interact with other atoms in the scope of chemical bonding; secondly, from the C 14 In terms of the electronic structure of the N atom in TAC, the N atom is a pentavalent atom, two of which occupy the 2s orbital, and the other three occupy the 2p orbital. Except for the lost one outer electron, the remaining four electr...

Embodiment 2

[0026] Embodiment 2, the impact of calcium salt addition

[0027] Dynamic light scattering technique is a common method to measure the hydrodynamic radius of nanoscale solutions. Here, dynamic light scattering is used to test the effect of calcium salt addition on cationic surfactant alkyltrimethylammonium chloride (C for short). n TAC) aqueous solution hydrodynamic radius of influence law. The cationic surfactant adopts C 8 TAC, C 10 TAC, C 12 TAC, C 14 TAC, C 16 TAC, C1 8 TAC, C 22 TAC, the concentration of various cationic surfactants in the solution is 3 times C cmc , C cmc Refers to the critical micelle concentration, measured by the surface tension method. The effects of different calcium salt additions (0, 1, 10, 50, 100mmol / L) on the hydrodynamic radius of various cationic surfactant solutions were tested, and the test results are shown in Table 1. Due to the low concentration of calcium salt added (0-100mmol / L), no salting-out will occur.

[0028] Table 1....

Embodiment 3

[0033] For small-scale static acid-rock reaction, the operation is as follows:

[0034] (1) Cut the natural calcite into 30mm×30mm×10mm squares, measure its length, width, height and quality;

[0035] (2) Use polyurethane PU glue (mass ratio 1:1) to seal the glue to ensure that only the upper surface is exposed to contact with the acid;

[0036] (3) Prepare a hydrochloric acid solution with a mass percent concentration of 20w% as a blank group. In addition, take 6 parts of the same hydrochloric acid solution, numbered 1, 2, 3, 4, 5, 6; add C 8 TAC, C 14 TAC, C 22 TAC, C n The concentration of TAC in hydrochloric acid solution is 3.0C cmc , C cmc Refers to the critical micelle concentration, measured by the surface tension method. Add calcium chloride to the other 3 parts of numbers 4, 5 and 6 at first to make the concentration of calcium chloride 50mmol / L; after adding calcium chloride, add C 8 TAC, C 14 TAC, C 22 TAC; C n The concentration of TAC in hydrochloric ac...

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Abstract

The invention discloses a retarded acid system. The retarded acid system comprises alkyltrimethylammonium chloride and a water-soluble calcium salt; and the alkyl group is a long-chain alkyl group containing 8-22 carbon atoms. The retarded acid system further comprises 1% of a corrosion inhibitor Mannich base and 1% of an iron ion stabilizer. In practical application, the use amount of the alkyltrimethylammonium chloride is 0.12-0.95 mass%, and the dosage concentration of the calcium salt is 10-100 mmol / L. The alkyltrimethylammonium chloride acts on a rock surface through physical adsorption,and covers the rock surface to perform hydrophobic wetting modification on the rock surface, so that hydrophilic H<+> is not prone to contact the rock surface, the reaction surface rate is controlled,and the acid rock reaction time is prolonged, thereby the retarding effect is achieved. The retarded acid has the advantages of low molecular weight, small damages to stratums, low viscosity, and improvement of the construction effect by cracking the complexity of crack networks through uneven etching of the wall surfaces of small cracks after entering the small cracks.

Description

technical field [0001] The invention relates to the field of petrochemical technology, in particular to a low-molecular-weight and low-damage retarded acid system. Background technique [0002] From a global perspective, carbonate oil and gas reservoirs are widely distributed and have great reserve potential. However, due to the strong heterogeneity of carbonate reservoirs, complex geological conditions and low productivity. Under normal circumstances, it is necessary to increase the production of the reservoir to achieve the purpose of understanding the reservoir and increasing the reserve and production. However, the relatively mature acidizing / acid fracturing technology has become one of the leading technologies for the production establishment, production increase and stable production of carbonate reservoirs. one. Comparing the effects of acidification / acid fracturing transformation at home and abroad, on the one hand, it is the innovation of the process, and on the o...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C09K8/74
CPCC09K8/74
Inventor 申鑫郭建春王世彬刘诚成刘嘉文胡鹏
Owner SOUTHWEST PETROLEUM UNIV
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