Hydroxyethyl Cellulose * Fracturing Fluid

In fracturing fluid, hydroxyethyl cellulose has multiple functions, and it has no effect on the oil layer itself, will not block the cracks, and can fractur e oil wells. It also has the general characteristics of water-based fracturing fluid, such as strong sand suspension ability and low friction resistance. Since 0.1%-2% water-alcohol mixture of high iodine salts such as potassium, sodium, and lead thickened by HEC is injected into the oil well under high pressure for fracturing, the fluidity can be restored within 48 hours. The water-based fracturing fluid made of HEC has basically no residue after liquefaction, and is particularly suitable for formations with low permeability and inability to reverse the residue. In alkaline environments, HEC forms complexes with solutions such as copper chloride, manganese chloride, dichromate and copper nitrate, specifically for use in fracturing fluids. The use of HEC can avoid viscosity loss and rupture of oil layers caused by high temperatures underground, and can still achieve good results at underground temperatures above 371°C. HEC is not easy to rot and deteriorate underground, has low residue, and basically will not block the oil line and cause underground pollution. It is much better than the plant gums (such as field sesbania, etc.) commonly used in fracturing. The specific effects are as follows:

1. Viscosity-increasing effect

Hydroxyethyl cellulose (HEC) has a significant viscosity-increasing effect in fracturing fluid. Fracturing fluid needs to have sufficient viscosity to carry proppants. Proppants are generally solid particles such as sand or ceramsite, and their function is to prop up rock cracks after fracturing and maintain the conductivity of the cracks. HEC can make the fracturing fluid thicker and smoothly transport the proppant to the deep cracks of the formation like a "conveyor belt". For example, in the fracturing operation of low-permeability reservoirs, fracturing fluids with sufficient viscosity can ensure that the proppant is evenly distributed in the cracks, effectively improving the seepage channels of the reservoir.

2. Suspended sand effect

It can suspend the proppant to prevent it from settling quickly in the fracturing fluid. During the fracturing construction process, especially in the fracture extension stage, if the proppant sedimentation rate is too fast, the proppant will accumulate at the bottom of the fracture and fail to effectively support the entire fracture. HEC is like a "suspended net". By increasing the structural viscosity of the fracturing fluid, the proppant particles are evenly dispersed in the fracturing fluid, ensuring that the proppant can reach the designed laying concentration and position in the fracture, thereby improving the fracturing effect.

3. Filtration control effect

HEC helps control the filtration loss of fracturing fluid. When the fracturing fluid is injected into the formation fracture, part of the liquid will be lost to the formation matrix under the action of pressure difference. If the filtration loss is too large, the amount of fracturing fluid in the fracture will be reduced, affecting the transportation of the proppant and the extension of the fracture. HEC can form a layer of filter cake on the fracture wall, reduce the filtration loss rate of the fracturing fluid, ensure that there is enough fracturing fluid to play a role in the fracture, so that the fracture can be smoothly extended according to the design requirements, and improve the effectiveness of fracturing.

4. Stabilization effect

It can stabilize the performance of the fracturing fluid. Under different formation temperature and pressure conditions, the performance of the fracturing fluid may change. HEC can enhance the shear resistance and temperature resistance of fracturing fluid.In high temperature environment, it can prevent the fracturing fluid from excessive degradation and loss of viscosity; in high shear conditions, such as when the fracturing fluid passes through the wellhead device and downhole tubing, HEC can keep the fracturing fluid at a certain viscosity and stability, ensuring the smooth progress of fracturing construction.