阅读说明：本技术 一种油井阻垢剂加药周期确定方法 (Oil well scale inhibitor dosing period determination method ) 是由 顾宇鹏 刘富洲 袁光喜 张永成 杨小东 庹涛 于 2020-06-09 设计创作，主要内容包括：本发明属于石油开采技术领域,具体涉及一种油井阻垢剂加药周期确定方法。该方法包括以下步骤：(1)根据日产液量的大小将同一油田不同区块中的各油井进行分级；(2)向某一级别油井中动液面最低的油井的油套环空中投入示踪剂,监测示踪剂浓度变化,利用示踪剂浓度变化反映阻垢剂浓度变化,确定阻垢剂浓度减小至最佳阻垢剂浓度所需的时间,根据所需时间确定该级别的油井阻垢剂加药周期；(3)依照步骤(2)的方法,确定该油田中其他级别的油井阻垢剂加药周期。本发明的方法能够确定油井经济、有效的加药周期,使油井在整个加药周期内都处于较优浓度阻垢剂的保护状态下。(The invention belongs to the technical field of oil exploitation, and particularly relates to a method for determining a dosing period of an oil well scale inhibitor. The method comprises the following steps: (1) grading each oil well in different blocks of the same oil field according to the daily liquid production amount; (2) putting a tracer into the air of an oil sleeve ring of an oil well with the lowest working fluid level in an oil well of a certain level, monitoring the concentration change of the tracer, reflecting the concentration change of the scale inhibitor by utilizing the concentration change of the tracer, determining the time required for reducing the concentration of the scale inhibitor to the optimal concentration of the scale inhibitor, and determining the dosing period of the scale inhibitor of the oil well of the level according to the required time; (3) and (3) determining the dosing period of the scale inhibitor of other oil wells in the oil field according to the method in the step (2). The method can determine the economic and effective dosing period of the oil well, so that the oil well is in the protection state of the scale inhibitor with better concentration in the whole dosing period.)

1. A method for determining a dosing period of an oil well scale inhibitor is characterized by comprising the following steps:

(1) grading each oil well in different blocks of the same oil field according to the daily liquid production amount;

(2) putting a tracer into the air of an oil sleeve ring of an oil well with the largest working fluid level value in an oil well of a certain level, monitoring the concentration change of the tracer, reflecting the concentration change of the scale inhibitor by using the concentration change of the tracer, determining the time required for reducing the concentration of the scale inhibitor to the optimal concentration of the scale inhibitor, and determining the dosing period of the scale inhibitor of the oil well of the level according to the required time;

(3) and (3) determining the dosing period of the scale inhibitor of other oil wells in the oil field according to the method in the step (2).

2. The method for determining the dosing cycle of the oil well scale inhibitor according to claim 1, wherein the initial concentration of the tracer is consistent with the initial concentration of the scale inhibitor.

3. The method for determining the dosing period of the oil well scale inhibitor according to claim 1, wherein the addition amount of the tracer is calculated according to the formula Q ═ Q × T + V) ×η× 10^-3，

Wherein Q is the addition of the single-well tracer agent in unit kg; q is daily oil well liquid yield, unit t/d; t is a prediction period and is a unit d; v is the oil sleeve annulus liquid mass, unit t; eta is the initial concentration of tracer in ppm.

4. The method for determining the dosing period of the oil well scale inhibitor according to any one of claims 1 to 3, wherein the initial concentration of the tracer is 2 to 4 times the concentration of the tracer corresponding to the optimal scale inhibitor concentration.

Technical Field

The invention belongs to the technical field of oil exploitation, and particularly relates to a method for determining a dosing period of an oil well scale inhibitor.

Background

In the process of developing an oil field, fluid in an oil-gas reservoir flows out of an oil-gas layer and flows to a ground gathering and transportation system through a shaft and a wellhead, and due to the change of temperature, pressure and the balance state of oil, gas and water, the concentration of scaling ions rich in formation water is changed, so that inorganic salts are easily deposited and scaled.

Scaling phenomena of different degrees can occur when the oil field enters the development stage of medium and high water-cut periods. Oil well scaling is a major factor that restricts oil field production, not only causes damage to the oil layer and reduces productivity, but also severely affects crude oil yield and pump inspection cycle of the oil well.

Adding the scale inhibitor is the simplest and most effective method for preventing oil well scaling at present, and the determination process of the dosing period of the existing scale inhibitor is as follows: firstly, a dosing period is estimated by combining other oil fields or the past experience of the oil field, and then the dosing period is gradually adjusted according to the field application effect.

The existing determination method of the dosing period mainly has the following problems: firstly, the method has certain blindness; secondly, the optimization adjustment time is long, and long-term dosing period exploration can cause overlarge dosing amount and increase treatment cost or cause poor treatment effect due to undersize dosing amount; thirdly, the liquid yield and the liquid level of the oil well can be changed in the production process, the economic and effective treatment purpose cannot be achieved by simply depending on field experience and lacking theoretical guidance, and the oil well cannot be effectively protected, so that the most common and important problem in the oil well scale treatment process is the determination of the optimal dosing period.

Disclosure of Invention

The invention aims to provide a method for determining a dosing period of an oil well scale inhibitor, which is used for providing an economic and effective dosing period and ensuring that an oil well is in a protection state of the scale inhibitor with a better concentration in the whole dosing period.

In order to achieve the purpose, the specific technical scheme of the method for determining the dosing period of the oil well scale inhibitor is as follows:

a method for determining a dosing period of an oil well scale inhibitor comprises the following steps:

(1) grading each oil well in different blocks of the same oil field according to the daily liquid production amount;

(2) putting a tracer into the air of an oil sleeve ring of an oil well with the lowest working fluid level in an oil well of a certain level, monitoring the concentration change of the tracer, reflecting the concentration change of the scale inhibitor by utilizing the concentration change of the tracer, determining the time required for reducing the concentration of the scale inhibitor to the optimal concentration of the scale inhibitor, and determining the dosing period of the scale inhibitor of the oil well of the level according to the required time;

(3) and (3) determining the dosing period of the scale inhibitor of other oil wells in the oil field according to the method in the step (2).

The oil well scale inhibitor dosing period determination method comprises the steps of grading oil wells in different blocks of the same oil field, taking daily liquid yield as a main influence factor influencing the dosing period of the scale inhibitor, and taking the working fluid level of the oil well as a secondary consideration factor; in addition, considering that in the oil wells of the same level divided according to the daily liquid production amount, the lower the working fluid level, the shorter the time required for completely updating the liquid in the oil sleeve annulus along with the continuous progress of the formation production and the wellhead production, the scale inhibitor dosing period of the oil well of the certain level is determined by determining the time required for reducing the scale inhibitor concentration corresponding to the oil well with the lowest working fluid level in the oil well of the certain level to the optimal scale inhibitor concentration, so as to ensure that the scale inhibitor concentration in the production liquid is higher than the optimal scale inhibitor concentration in the whole dosing period. For the oil wells in the same oil field, the physical property difference of each well is small, the chemical adding period of the oil well of the same level can be determined by measuring the chemical adding period of the scale inhibitor of a part of representative oil wells, and the chemical adding period of the scale inhibitor of the oil well of the same oil field has guiding significance. The optimum antiscalant concentration was determined from laboratory experiments.

Generally, there is a defined correspondence between the initial concentration of tracer added and the initial concentration of antiscalant added. Preferably, the initial concentration of the tracer is consistent with the initial concentration of the scale inhibitor to make the determination more accurate.

Further, the amount of the tracer to be added is calculated by the formula Q ═ Q × T + V) ×η× 10^-3Q is the addition of a single-well tracer agent and is unit kg, Q is the daily liquid production of the oil well and is unit T/d, T is the prediction period and is unit d, V is the annular liquid mass of the oil casing and is unit T, η is the initial concentration of the tracer agent and is unit ppm, the initial concentration is determined according to an indoor test, T is the time required for detecting the concentration of the scale inhibitor in a produced liquid, and the numerical value of the initial concentration is related to the type of the oil well.

Because the concentration of the tracer in the produced liquid is reduced quickly in the early stage of putting into the oil casing annulus, the concentration is also the same as that of the scale inhibitor, the initial concentration of the scale inhibitor is properly larger than the optimal scale inhibitor concentration, but the treatment cost is higher due to the overhigh initial concentration, preferably, the initial concentration of the scale inhibitor is 2-4 times of the optimal scale inhibitor concentration, and correspondingly, the initial concentration of the tracer is 2-4 times of the tracer concentration corresponding to the optimal scale inhibitor concentration.

Drawings

FIG. 1 shows the scale inhibition ratios of different types of scale inhibitors in the examples of the present invention;

FIG. 2 shows the scale inhibition ratios of PAS type scale inhibitors at different concentrations in examples of the present invention;

FIG. 3 shows the results of detection of tracer concentration in the 27-well on the 206-side of the row in an embodiment of the invention;

FIG. 4 is a graph of the tracer concentration measurements for rows 206-10 of wells in an embodiment of the present invention;

FIG. 5 shows the detection results of tracer concentration in 2-40 wells in the embodiment of the invention.

Detailed Description

The application of the method of the present invention will be specifically described with reference to the following examples. It should be noted that the examples given in this specification are only for the purpose of facilitating understanding of the present invention, and they are not intended to be limiting, i.e., the present invention may be embodied in other forms than those shown in the specification. Therefore, any technical solutions formed by equivalent substitution or equivalent transformation fall within the protection scope of the present invention.