Oilfield cementing technology mainly refers to the construction technology process between the cement slurry and the wellbore casing, that is, the process of injecting the cement slurry into the annulus between the wellbore and the casing. The purpose of doing this is to separate and support between layers, and protect casing. In practical construction, cementing quality technology determines the quality of cementing, which is related to the service life of oil wells and the protection of petroleum energy. Therefore, many aspects of cementing process technology should be considered, such as well preparation stage, cementing materials, cementing facilities and equipment cementing construction management, cementing construction quality, etc. With the further maturity and application of drilling technology, natural gas, ground well gas and geothermal resources have gradually been widely concerned and valued. Under the current social and economic system, people are more and more in pursuit of living energy, closer to nature and environmental protection. However, with the continuous improvement of environmental requirements, disorderly exploitation and excessive repeated exploitation of energy, on the other hand, they have to pay more attention to environmental protection Reasonable use of energy, while protecting the environment, will promote the cementing process is facing enormous challenges and tense situation.

Main techniques for enhancing cementing quality in 1 Oilfield

1.1 cementing fluid cementing technology

The main reason is that the BF cementing fluid can't be used under the condition of optimizing the cementing fluid. The use of UF drilling and MTC cementing technology can improve the compatibility of drilling fluid and cementing fluid, which can effectively deal with the incompatibility between conventional cementing slurry and drilling fluid, and achieve good barrier and cementation effect of multi-layer interface, especially the cementation effect of the second layer, so as to reduce the probability of mutual channeling of oil, gas and water fluid, and improve the cementing effect In addition, the diffusion and penetration of activator can effectively strengthen the formation of cement slurry, and block the circulation leakage and the fall of cement slurry column. Compared with the common oil well cement slurry, the cement slurry with auxiliary additives is also more affordable, and has the characteristics of low water loss, rapid development, good stability, environmental protection and pollution resistance. At present, the domestic cementing fluid technology has basically replaced the traditional displacement mechanism and displacement technology. For environmental protection, it can effectively deal with the environmental pollution caused by waste gas drilling fluid discharge, so that it can be improved.

1.2 foam cementing technology

Foam cementing technology has two practical methods of aeration, one is chemical preparation in cement slurry by chemical reaction to produce nitrogen and other additional auxiliary agent such as foam stabilizer and so on forming a more stable foam cement. Another conventional foam method is foam cement formed by mechanical aeration. The components of foam cement slurry consist of paste, nitrogen, foam stabilizer and cement slurry preparation. During the construction of the site, the cement truck is used to mix the water and mixed preparations into a paste. Then, the slurry is injected into the nitrogen gas through the nitrogen pump to form foam cement slurry. As for the amount of nitrogen injected, it can be controlled by the computer itself and blended according to the density of the cement slurry prepared at the site. Foamed cement slurry has the following advantages: its density is low, and its minimum can reach 0.72g/cm. Low density is beneficial to enhance the quality and efficiency of cement slurry. This is due to the high adhesive viscosity of the slurry, which can replace the slurry that is not easy to flow; the compressive strength of the slurry is higher than that of the past; due to its anti compression property, it can compensate the weight loss of the cement slurry, so as to prevent gas channeling; under the premise of high temperature and high pressure, compared with the past water slurry, it has higher compressive strength The slurry has better toughness and high temperature stability, so it can be used in deep well cementing operation; similarly, its cost is lower, about 30% lower than the previous cement slurry economic cost.

1.3 level cementing technology

In horizontal cementing, the following aspects should be paid attention to: the free water should be well controlled to reduce or eliminate the free water as far as possible; the annulus should be kept as clean as possible; the casing should be in the middle and keep the upper body down, and the casing should be rotated; the performance of the cement should be excellent enough to be compatible with cement slurry, drilling fluid, flushing fluid, isolation fluid, etc It is necessary to correctly use the reasonable rheological design, grasp the relationship between formation pressure and void pressure, carry out turbulent displacement as effectively as possible, and pay attention to using ampj system cement method in slim hole.

1.4 underbalanced well cementing technology

Underbalanced drilling technology, pioneered by air drilling, began in the 1950s. In the 1970s, in view of the exploration and development situation at that time, people's attention focused on the high pressure, high permeability and high yield oil and gas fields, and did not pay much attention to the low pressure, low permeability and low yield oil and gas fields, so the technology did not receive special attention. Underbalanced drilling started late in China. Xinjiang, Zhongyuan, Daqing, Dagang and other oilfields have carried out underbalanced drilling test and completion technology of underbalanced well.

2. The improvement technology of oilfield cementing development in China

2.1 cementing technology for tertiary infill wells

In order to achieve stable oil production, China attempts to study the technology of three times infill drilling in thin and poor reservoirs and outer reservoirs. However, due to the complexity of underground operation and the need for cementing quality, it is necessary to implement joint research on the drilling system, so as to lay a sufficient foundation for the tertiary infill technology.