Zaczyny cementowe z dodatkiem nanorurek węglowych do uszczelniania otworów wiertniczych o wysokiej temperaturze i ciśnieniu złożowym (150°C, 90 MPa)

Nafta-Gaz ◽  
2021 ◽  
Vol 77 (5) ◽  
pp. 323-331
Author(s):  
Miłosz Kędzierski ◽  
◽  
Marcin Rzepka ◽  

The article presents the results of the influence of carbon nanotubes on the mechanical parameters of cement stones under high temperature and pressure conditions (150°C, 90 MPa). The tests used multi-walled carbon nanotubes (MWCNTs) with an external diameter of 10–20 nm and a length of 10–30 μm. Cement slurries contained 0.1% of CNTs bwoc (by the weight of cement). Laboratory tests of cement slurries were carried out at the Oil and Gas Institute – National Research Institute. The tests were carried out under conditions of increased pressure and temperature at 150°C, 90 MPa. Cement slurries were prepared on the basis of class G drilling cement. Developing recipes were guided by the requirements to be met by cement slurry for the cementing of casing in the conditions of high temperature and reservoir pressures. The densities of tested slurries ranged from 1900 kg/m3 to 2250 kg/m3 (slurries with the addition of hematite). The cement slurries were tested for density, fluidity, rheological parameters, filtration and thickening time. Compressive strength tests and measuring adhesion were carried out after 2, 7, 14 and 28 days. Cement slurry recipes with very good technological parameters were developed and after curing (after 28 days of hydration) had very high values of compressive strength, reaching up to 45 MPa. Cements were characterized by high values of adhesion to pipes reaching up 7 MPa after 28 days. The research showed significant information about possible applications of carbon nanotubes to modify the cement slurry under conditions of high temperature and pressure. The conducted tests confirmed that the addition of even small amounts of CNTs improves the mechanical parameters of the cement stone compared to the base sample without such addition, and also reduces the thickening time of cement slurries and reduces filtration. It is investigated that CNTs addition increases the viscosity and yield point of cement slurry. As a result, slurries with the addition of MWCNTs will more effectively displace the mud from the borehole and significantly affect the quality of cementation.

Nafta-Gaz ◽  
2021 ◽  
Vol 77 (3) ◽  
pp. 200-2017
Author(s):  
Łukasz Kut ◽  

Works related to the drilling of a deep borehole must take into account the specific conditions at its bottom. This applies especially to high temperatures, exceeding 90–100°C, and pressures of 60–80 MPa. Such difficult downhole conditions have often posed many problems when developing appropriate compositions of cement slurries used for sealing columns of casing pipes. With each passing year, drilling companies make deeper and more complicated boreholes, more and more often exceeding 3000 m, which require the use of specially developed recipes of cement slurries when sealing the casing column. In deep boreholes (with very high temperature and pressure), a serious problem is to ensure a long pumping time of the cement slurry, which should be characterized by low viscosity, little or no free water and the lowest filtration possible. Therefore, it is necessary to select appropriate retardants that are resistant to high temperatures and additives ensuring the appropriate technological parameters of the slurries and cement stone. Pressure and temperature parameters increase with the depth of the borehole. Reservoir waters (brines of different mineralization) largely affect the hardened cement slurry, therefore cement slurries intended for deep boreholes should contain in their composition additives that increase thermal resistance, delay setting, lower filtration and improve resistance to chemical corrosion caused by the action of brines reservoir. The aim of the laboratory research was to develop innovative formulas of cement slurries for sealing boreholes, both crude oil and geothermal, with increased temperatures (up to about 130°C) located in the Carpathian region. During the implementation of the topic, laboratory tests were carried out on both cement slurries and cement stones obtained from them. Due to the industry’s interest in acquiring energy from sources other than crude oil and natural gas, a broader scope of laboratory tests covered cement slurries for sealing geothermal boreholes with controlled rheological parameters, which can be used at high reservoir temperatures to seal deep boreholes. The cement slurries were prepared with tap water with the addition of potassium chloride in the amount of 3, 6 and 10% bwow (in relation to the amount of water). The following agents were successively added to the mixing water: defoaming, adjusting the setting and thickening time, plasticizing and reducing filtration. Cement slurries were made with the addition of 10% latex and a latex stabilizer in the amount of 1% bwoc (both components in relation to the weight of dry cement). The other ingredients: microcement (nanocement), microsilica, hematite and cement were mixed together and then added to the mixing water. All cement slurries were prepared on the basis of drilling cement G. When all components blended, the cement slurry was mixed for 30 minutes followed by laboratory measurements such as: density, fluidity, readings from the Fann apparatus, water retention, filtration, thickening time. From among the developed cement slurries, those with the best rheological parameters were selected, then samples of cement stones were prepared from them. Cement slurries were cured for 48 hours in an environment of high temperature and pressure (downhole conditions). The obtained cement stones were tested for: compressive strength, bending strength, porosity, adhesion of cement stone to steel pipes.


Nafta-Gaz ◽  
2021 ◽  
Vol 77 (2) ◽  
pp. 106-117
Author(s):  
Miłosz Kędzierski ◽  
◽  
Marcin Rzepka ◽  
Marcin Kremieniewski ◽  
◽  
...  

The article presents the results of testing the influence of carbon nanotubes on the mechanical parameters of cement stones under HPHT conditions. Multi-walled carbon nanotubes (MWCNTs) with an external diameter of 10–20 nm and a length of 10–30 μm were used for testing. 0.1% of carbon nanotubes was added to the cement slurry. Laboratory tests of cement slurries were carried out at Oil and Gas Institute – National Research Institute. The tests were carried out under conditions of increased pressure and temperature in the temperature range of 60–130°C and the pressure range of 25–80 MPa. CEM I 42.5R Portland cement and Class G drilling cement were used to make the slurries at temperature of 60oC. Cement slurries for temperatures from 80oC to 130oC were prepared on the basis of class G drilling cement. The recipes were developed on the basis of the requirements to be met by cement slurry for the cementing of casing under conditions of very high temperatures and reservoir pressures. The densities of tested slurries ranged from 1,840 kg/m3 (slurries at a temperature of 60°C) to 2.250 kg/m3 (slurries with the addition of hematite).Compressive strength tests and adhesion measurements were carried out after 2, 7, 14 and 28 days. Cement slurry recipes with very good technological parameters were developed, which after curing (after 28 days of hydration) showed very high values of compressive strength, reaching up to 44 MPa. Cements were characterized by high values of adhesion to pipes reaching up 8 MPa after 28 days and flexural strength of about 11 MPa. The test results show that the addition of carbon nanotubes has a positive effect on the mechanical strength of cement stones with their addition. The stones modified in this way are characterized by high compressive strength and high adhesion to steel pipes. Further research is needed to determine the influence of carbon nanotubes on the microstructure of hardened cement slurries. It is also necessary to conduct further research on the determination of the optimal amounts of these agents and the selection of the most compatible additives for cement slurries that work optimally in combination with nanoparticles.


2018 ◽  
Vol 213 ◽  
pp. 207-214 ◽  
Author(s):  
Michael Hack ◽  
Wolfgang Korte ◽  
Stefan Sträßer ◽  
Matthias Teschner

1999 ◽  
Vol 122 (1) ◽  
pp. 22-26 ◽  
Author(s):  
M. Law ◽  
W. Payten ◽  
K. Snowden

Modeling of welded joints under creep conditions with finite element analysis was undertaken using the theta projection method. The results were compared to modeling based on a simple Norton law. Theta projection data extends the accuracy and predictive capability of finite element modeling of critical structures operating at high temperature and pressure. In some cases analyzed, it was found that the results diverged from those gained using a Norton law creep model. [S0094-9930(00)00601-6]


2020 ◽  
Author(s):  
Dapeng Wen ◽  
Yongfeng Wang ◽  
Junfeng Zhang ◽  
Pengxiao Li ◽  
Zhen-Min Jin

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