CN112552885B - Superhigh temperature resistant 180 ℃ tackifying type well completion fluid and workover fluid - Google Patents

Abstract

The invention relates to a 180 ℃ ultrahigh temperature resistant tackifying type well completion fluid and workover fluid, and belongs to the field of oil and natural gas exploitation. The raw materials comprise 1wt% of stabilizing agent, 1.1wt% of water-absorbing colloidal particles and the balance of water. After aging for 24 hours at 180 ℃, the viscosity range of the workover fluid is 87-650 mPa.s, and the viscosity can be kept stable at 180 ℃. The preparation method can meet the well repair requirement of the high-temperature oil and gas well, is simple and convenient to prepare, has strong field operability, and has good application prospect.

Description

A Viscosifying Completion Fluid and Workover Fluid Resistant to Ultra-high Temperature 180°C

technical field

The invention relates to an ultra-high temperature-resistant 180°C viscosity-increasing well completion fluid and workover fluid, belonging to the field of oil and natural gas exploitation.

Background technique

The development of deep and ultra-deep oil and gas reservoirs will be the main force of future oil and gas production. The deep high-temperature environment poses severe challenges to downhole working fluids. In workover operations, carboxymethyl cellulose (CMC) and xanthan gum are commonly used to increase the viscosity of workover fluids. Carboxymethyl cellulose is a water-soluble cellulose ether. Its solution is neutral or slightly alkaline. It has the characteristics of thickening and bonding, but it will degrade rapidly at high temperature and its viscosity will be greatly reduced. The viscosifying effect of xanthan gum has good effects in improving foam stability and shear stability, but its high temperature resistance is limited, and it is prone to thermo-oxidative degradation at high temperatures, and the dosage is large and the production cost is high. Therefore, in view of the unsatisfactory viscosity-increasing effect of traditional viscosity-increasing workover fluids at high temperatures, it is urgent to develop a high-temperature-resistant viscosity-increasing completion fluid and workover fluid for circulating well washing and sand carrying.

The stability of workover fluid is a key factor for safe and efficient workover operations in ultra-high temperature oil and gas wells. During the workover process, the formation temperature is too high, and the traditional viscosity-increased workover fluid is not resistant to high temperature and is easy to leak, so it cannot carry sand and flow back. Therefore, it is necessary to improve the performance of the workover fluid, including basic requirements such as non-degradation at ultra-high temperature, easy circulation, and viscosity increase. In 2012, Xu Yandong and others developed a workover and completion fluid (Chinese patent: CN 102618225A). The workover and completion fluid includes the preparation of base fluid and additives. The prepared base fluid is formation water or a mixture of formation water and surface water . Among them, the additives include tackifiers, corrosion inhibitors, and stabilizers. All kinds of raw materials have good compatibility with the formation, and have the characteristics of high temperature resistance of 120°C and high salinity. The on-site preparation process is simple and meets the requirements of protecting the reservoir.

In 2014, Sun Lin and others studied the application of temperature-resistant and salt-resistant xanthan gum system in oilfield development. Xanthan gum has a special molecular structure and has obvious technical advantages in oil field development. It has strong water solubility, thickening, salt resistance, and pollution resistance. It also has good shear stability and unique flow characteristics. Denaturation and other advantages; but it is prone to thermo-oxidative degradation at high temperature. (Sun Lin, Wei Peng, Fu Qiang, et al. Research progress on the application of heat-resistant and salt-resistant xanthan gum system in oilfield development[J]. Applied Chemical Industry, 2014, 43(12): 2279-2284.)

In 2017, Chen Jianguang and others developed a viscosifying suspension modifier and its application (Chinese patent: CN109384884A). The viscosifying suspension modifier includes the following components: hydroxymethyl starch, N,N'-methylene Base bisacrylamide, thiosulfate. The viscosity-increasing suspension modifier can be well dissolved in high-salinity brine workover fluids, significantly increasing the viscosity of brine workover fluids, thereby improving the suspension capacity of brine workover fluids, which is conducive to smooth workover operations conduct.

In 2020, Liu et al. studied the performance of nanocomposite membranes composed of carboxymethyl cellulose, cellulose nanofibers and silica, in which carboxymethyl cellulose can be used as a thickener and flotation agent; but at high temperature Easily degrades rapidly. (Jianxin Liu, et al.Nanocomposites membranes from cellulose nanofibers,SiO ₂ and carboxymethyl cellulose with improved properties.Carbohydrate Polymers[J],2020:11588.)

The current solid-phase viscosity-increasing workover fluid system represented by xanthan gum completely degrades after 24 hours of aging at ultra-high temperature of 180 °C; CMC remains stable at 120 °C for 16 hours, but it is prone to thermal oxidation degradation, which limits It is used for workover of ultra-high temperature oil and gas wells. In view of the unsatisfactory viscosifying effect of traditional viscosity-increasing workover fluids at high temperatures, it is urgent to design an ultra-high temperature viscosity-increasing completion fluid and workover fluid to ensure safe, smooth and efficient downhole operations.

Contents of the invention

The purpose of the present invention is to develop a kind of anti-ultra-high temperature 180°C viscosity-increasing completion fluid and workover fluid, which is used for circulating sand carrying in oil and gas wells.

The invention provides a technical solution:

A kind of anti-ultra-high temperature 180°C viscosity-increasing completion fluid and workover fluid. The raw materials are mainly composed of stabilizer and water-absorbing colloidal particles, and the fluid is mixed with clean water. The stabilizer is at least one of urotropine, phenolic resin and polyethyleneimine.

In other embodiments of the present invention, the above-mentioned stabilizer is urotropine, phenolic resin, and polyethyleneimine, which are diluted with water in a certain proportion.

In other embodiments of the present invention, the above-mentioned raw materials also include water-absorbing colloidal particles, the water-absorbing colloidal particles are SAP-KA01 (commercial product, Chengdu Lite Energy Technology Co., Ltd., particle size 0.8-1.5mm, water absorption ratio: 67.2), At least one of SHK-220A (commercial product, Chengdu Lite Energy Technology Co., Ltd., particle size 0.6-1.0mm, water absorption ratio 152.17), the water-absorbing colloidal particles contain sulfonate groups.

The beneficial effects of the ultra-high temperature 180°C viscosity-increasing completion fluid and workover fluid and the preparation method thereof provided by the embodiment of the present invention are as follows:

Partial degradation of water-absorbing colloidal particles at high temperature can increase the viscosity of completion fluid and workover fluid; stabilizers can improve the effects of viscosity control and stabilization of completion fluid and workover fluid.

Description of drawings

Fig. 1 is the curve diagram of the viscosity of completion fluid and workover fluid in Example 1 of the present invention as a function of temperature;

Fig. 2 is the curve diagram of the viscosity of the completion fluid and the workover fluid in Example 2 of the present invention along with aging time;

Fig. 3 is a graph showing the variation of the viscosity of the completion fluid and the workover fluid with the colloidal particle concentration in Example 3 of the present invention.

Detailed ways

In order to make the purpose, technical solutions and advantages of the embodiments of the invention more clear, the following will clearly and completely describe the technical solutions in the embodiments of the present invention. Those who do not indicate the specific conditions in the examples are carried out according to the conventional conditions or the conditions suggested by the manufacturer. The reagents or instruments used were not indicated by the manufacturer, and they were all conventional products that could be purchased from the market.

An ultra-high temperature resistant 180°C viscosity-increasing completion fluid and workover fluid according to an embodiment of the present invention and its preparation method will be described in detail below.

A kind of anti-ultra-high temperature 180°C viscosity-increasing completion fluid and workover fluid. The raw materials mainly include stabilizer and water-absorbing colloidal particles. The stabilizer is at least one of urotropine, phenolic resin and polyethyleneimine.

In other embodiments of the present invention, the above-mentioned stabilizer is urotropine, phenolic resin, and polyethyleneimine, which are diluted with water in a certain proportion.

In other embodiments of the present invention, the above-mentioned raw materials also include water-absorbing colloidal particles, the water-absorbing colloidal particles are SAP-KA01 (commercial product, Chengdu Lite Energy Technology Co., Ltd., particle size 0.8-1.5mm, water absorption rate 67.2), SHK - At least one of 220A (commercial product, Chengdu Lite Energy Technology Co., Ltd., particle size 0.6-1.0mm, water absorption ratio 152.17), the water-absorbing colloidal particles contain sulfonate groups.

In detail, a kind of anti-ultra-high temperature 180°C viscosity-increasing completion fluid and workover fluid will be prepared, and 1% stabilizer will be diluted with clean water, and the diluted stabilizer will be added to quantitative clean water and stirred to make it evenly mixed before adding Absorb material and stir to make it completely absorb water and swell. The characteristics and performance of the present invention will be described in further detail below in conjunction with the examples.

Example 1

In the 500ml beaker, add quantitative clear water first according to the data in Table 1, and then use quantitative clear water to dilute 1% stabilizer to 20% according to the ratio of (hexamethamine, polyethyleneimine, phenolic resin according to 1:1:1) and add to In the beaker, stir for 15-30 minutes until it is completely mixed, then add 1.1% SKH-220A water-absorbing colloidal particles, then stir fully to make it completely absorb water and swell, put it into a high-temperature reactor, seal the container, and put it in a constant temperature of 180°C In a dry box, let it stand for 24 hours to prepare a super high temperature 180°C viscosity-increasing completion fluid and workover fluid. After cooling, heat the workover fluid in a water bath and gradually raise it from 20°C to 90°C, and use a six-speed rotational viscometer to test the samples at 600rpm (1022s ^-1 ), 300rpm (511s ^-1 ), 200rpm (340.7 s ⁻¹ ) and apparent viscosity at 100 rpm (170.3 s ⁻¹ ). The experimental results are shown in Table 1.

Table 1 Viscosity and temperature relationship

From the data in Table 1, it can be known that the viscosity of workover fluid decreases gradually with the increase of temperature when the shear rate is constant.

Example 2

Add quantitative water to the 500ml beaker according to the data in Table 2, then use quantitative water to dilute 1% stabilizer to 20% according to the ratio of polyethyleneimine and phenolic resin, add it to the beaker, and stir for 15-30min After completely mixing, add 1.1% SKH-220A water-absorbing colloidal particles, and then fully stir to make it completely absorb water and swell. Thus, a kind of anti-ultra-high temperature 180°C viscosity-increasing completion fluid and workover fluid was prepared. Then put it into a high-temperature reactor and age it at 180°C for 1 to 4 days, and use a six-speed rotational viscometer to test the samples at 600rpm (1022s ^-1 ), 300rpm (511s ^-1 ), 200rpm (340.7s ^-1 ) , apparent viscosity at 100 rpm (170.3 s ⁻¹ ) and 6 rpm (10.22 s ⁻¹ ). The experimental results are shown in Table 2 below.

Table 2 aging time and viscosity relationship

From the data in Table 2, it can be known that the viscosity of the workover fluid decreases gradually with the increase of aging time when the shear rate is constant.

Example 3

Add quantitative water to the 500ml beaker according to the data in Table 3, and use quantitative water to dilute 1% stabilizer (phenolic resin, urotropine, polyethyleneimine at 1:2:1) to 20% and add it to the beaker , stir for 15 to 30 minutes until completely mixed, then add 0.7% to 1.1% SKH-220A water-absorbing colloidal particles, then fully stir to make it completely absorb water and swell, put it into a high-temperature reactor, seal the container, and put it at 180°C In a constant temperature drying oven, let it stand for 24h. Thus, a kind of anti-ultra-high temperature 180°C viscosity-increasing completion fluid and workover fluid was prepared. After aging for 24 hours at 180°C with a particle concentration of 0.7% to 1.1%, the samples were tested at 600rpm (1022s ^-1 ), 300rpm (511s ^-1 ), 200rpm (340.7s -1 ) with a six-speed rotational viscometer. ^-1 ), 100 rpm (170.3 s ^-1 ), 6 rpm (10.22 s ^-1 ) and 3 rpm (5.11 s ^-1 ). The experimental results are shown in Table 3 below.

Table 3 The relationship between the concentration and viscosity of different colloidal particles

From the data in Table 3, it can be seen that at a constant shear rate, the viscosity of the workover fluid increases gradually with the increase of the colloidal particle concentration.

The embodiments described above are some, not all, embodiments of the present invention. The detailed description of the embodiments of the invention is not intended to limit the scope of the claimed invention but to represent only selected embodiments of the invention. Based on the embodiments of the present invention, all other embodiments obtained by persons of ordinary skill in the art without creative efforts fall within the protection scope of the present invention.

Claims (3)

1. An ultra-high temperature resistant 180°C viscosity-increasing completion fluid and workover fluid, composed of stabilizers and water-absorbing colloidal particles, mixed with clean water, characterized in that the components according to their mass percentages are: 1% stable agent, 1.1% water-absorbing colloidal particles, the stabilizer is composed of urotropine, phenolic resin, and polyethyleneimine in a mass ratio of 0-2:1-2:1, and the water-absorbing colloidal particles are SAP-KA01 and SHK - At least one of 220A. 2. A super-high temperature resistant 180°C viscosity-increasing completion fluid and workover fluid according to claim 1, characterized in that the stabilizer needs to be diluted with clean water. 3. A kind of anti-ultra-high temperature 180°C viscosity-increasing completion fluid and workover fluid as claimed in claim 2, characterized in that when the water-absorbing colloidal particles SHK-220A is added to the mixed solution, knotting is easy to occur, and the colloidal particles cannot It will automatically absorb water until it swells completely, so when adding it, it should be stirred in time to make it completely absorb water and swell.

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