4.  Future research direction

In recent years, PetroChina has made great progress in the research, development and application of cementing materials and cementing slurry system, but there is still a certain distance for materials suitable for cementing in complex deep wells, ultra deep wells, complex natural gas wells, tight oil and gas wells under large volume fracturing conditions, complex gas storage wells, deep complex salt gypsum wells, low-temperature deep-water cementing in the ocean, etc., with special cement The research of slurry, admixture and high performance multifunctional cement slurry system is lagging behind.

Compared with foreign countries, the current admixture products are single in variety and insufficient in refinement; lack of high-performance high-temperature retarder and loss reducing agent; lack of in-depth research on external admixture, lack of high-performance weighting agent and reducing material; lack of serialization, mainly concentrated in the stage of medium and low temperature, medium and high temperature and general-purpose admixture, lack of ultra-low temperature and ultra-high temperature water Compared with foreign countries, the slurry system has a certain gap in ultra-high density cement slurry, ultra-low density cement slurry and toughness cement slurry.

In order to meet the needs of cementing in the increasingly complex wellbore environment, it is necessary to deepen the research on the mechanism of cementing materials, accelerate the research on new cementing materials, strengthen technical reserves, strengthen independent innovation, focus on solving the key technical problems in cementing production, and improve the guarantee and market competitiveness of cementing engineering technology for exploration and development. The following research work is recommended:

1) Mechanism study

It mainly includes the research on the mechanism of the relationship between cement slurry and cement stone, the research on the mechanical properties and long-term sealing mechanism of cement stone, the research on the mechanism of enhancing the sealing ability of cement sheath, casing and formation, the research on the sealing failure criterion and sealing failure mechanism of cement sheath, the research on the tight packing mode and the interaction mechanism between materials (mainly to achieve the minimum water demand and good tight packing); elastic-plastic Study on the mechanism and modification technology of cement stone (to achieve high strength, low modulus of elasticity, high impact toughness and long-term sealing of the annulus).

2) Perfect cement slurry system and performance

It mainly includes ultra-high density and ultra-low density cement slurry, large temperature difference cement slurry system and series of admixtures, high strength and toughness cement and series of admixtures, anti-corrosion materials and anti-CO2 corrosion cement slurry system, low temperature and high temperature salt resistant cement slurry system and supporting admixtures, amps type fluid loss reducer and corresponding cement slurry system, latex salt resistant cement, etc. A lot of work has been done on the research of the above cement slurry system, and good results have been achieved in the field application. However, it is necessary to further improve the admixture and cement slurry formula, improve the reliability and field applicability.

3) Research and development of new cementing materials and additives

It mainly includes research on high-performance high-temperature retarder, high-performance high-temperature loss reducing agent and stability of cement slurry at high temperature, research on broad-spectrum admixture (mainly refers to the admixture that is not sensitive to temperature, pressure and other conditions), research on anti shrinkage material and micro crack material of cement stone, research on ultra-high temperature material of cement stone, research on self repairing material, research on non cement base material Materials, supramolecular materials, nanomaterials, etc. The above materials have just carried out preliminary research or less research. In order to provide technical reserves for cementing and long-term sealing of complex wells, more research efforts are needed.