Oil well cement
Oil well cement is one kind of special cement just like white cement and refractory cement.What is oil well cement? Oil well cement is used for cementing of oil well and gas well, also known as plugging cement. In the oil or natural gas exploration and production, set the steel tube into the h
Send inquiryOil well cement is one kind of special cement just like white cement and refractory cement.
What is oil well cement? Oil well cement is used for cementing of oil well and gas well, also known as plugging cement. In the oil or natural gas exploration and production, set the steel tube into the hole, reinjection cement slurry, the main function of oil cement is to cement and seal steel tube with the surrounding strata, the packer in the formation of oil, gas, water, prevent string approach each other, in order to form an oil flow channel with good insulation from the reservoir to cut off the ground.
How to Build
There are two production processes for oil well cement. One is to produce clinker composed of specific minerals to meet the chemical and physical requirements of a certain grade of cement. The other is to use the basic oil well cement (grade G or Grade Hcement), adding the corresponding admixture, in order to meet the technical requirements of grade cement. The former approach tends to bring more difficulties to the cement plant, so the second approach is
widely used.
Oil well cement manufacturing process is the same as Portland cement manufacture, but there are some basic requirements to be meted in some production process.
In the raw materials of oil well cement, calcium oxide content of limestone should be high, potassium and sodium content of clay should be low, finished raw meal should be sent into homogenization to ensure the composition of the raw meal into kiln.
During the process of clinker calcining, the proportion of clinker and the content of free calcium oxide must be strictly controlled, and the specified control indexes must be reached.
After the cement is put into a storage silo, it should be fully homogenized to ensure that the quality of products from the cement factory all meet the technical requirements stipulated in the standard.
In a short, oil well cement production can be divided into five steps:
Raw materials preparation
Raw meal grinding
Clinker production
Cement grinding
Storing or bagging
Notes: The situation of oil well and gas well is very complicated, in order to adapt to the specific conditions of different oil and gas well, it is necessary to add some admixtures in cement, such as a weight-adding agent, lightening
agent, or retarder.
The basic requirements of oil well cement are as follows:
The cement slurry should have certain fluidity and suitable density in the process of well injection
After the cement slurry is injected into the well, it should condense quickly and reach a certain strength in a short time.
The hardened cement slurry shall have good stability, impermeability and corrosion resistance.
Industry Applications
In general, the temperature and pressure at the bottom of the well increase with the increase of the well depth. For every 100 m, the temperature increases by about 3℃, and the pressure increases by 1.0 ~ 2.0mpa. Therefore, the influence of high temperature and high pressure,
especially high temperature on various properties of cement is the most important problem in the production and use of oil well cement. The high temperature makes the strength of Portland cement decrease significantly,
Therefore, different concentrations of oil Wells should use cement in different compositions. According to GB 10238-98, China’s oil well cement is divided into nine grades, including ordinary (0), medium sulfate
resistant (MSR), and high sulfate resistant (HSR). The application scope of oil well cement at all levels is as follows:
Class A: For cementing from surface to 1830 m depth without special performance requirements are required. Only the normal type.
Class B:
Suitable for demanding downhole conditions and early strength, suitable
for cementing from surface to 1830 m well depth. It is divided into two
types: medium sulfate resistant and high sulfate resistant.Class C:
Suitable for downhole conditions with the high requirement in the early
strength, apply for cementing from surface to 1830 m depth. It can be
divided into three types: common type, moderate type, and high type.Class D:
Suitable for use under medium temperature and pressure downhole
conditions, divided into two types: medium and high sulfate resistance.Class E: Suitable for use under high temperature and pressure conditions include two types: medium and high sulfate resistant.
class F: Suitable for ultra-high temperature and pressure conditions, divided into medium and high sulfate resistance type.
Class G, Class H: Basic oil well cement, divided into medium sulfate resistant type and high sulfate resistant type.
J-class: Suitable for cementing 3 660 ~ 4 880 m well depth under ultra-high temperature and pressure conditions.
