High temperature resisting thixotropic cement slurry system and preparation method thereof

Abstract

The invention discloses a high temperature resisting thixotropic anti-fluid-channeling well cementing cement slurry system. The high temperature resisting thixotropic anti-fluid-channeling well cementing cement slurry is prepared from the following components in parts by weight:100 parts of cement, 1 to 4 parts of a thixotropic agent, 8 to 13 parts of micro silicon, 2 to 4 parts of a dispersing agent, 2 to 3 parts of a retarder, 2 to 3 parts of a fluid loss agent, 0.1 to 0.25 part of sodium hydroxide, 0.5 to 1 part of a defoaming agent, 30 to 35 parts of silica sand of180 meshes, 15 to 20 parts of silica sand of 80 meshes and 53 to 60 parts of water. The cement system disclosed by the invention has the following characteristics: firstly, the thixotropy performance is good under high temperature condition and an internal structure is easy to destroy after a machine is shut down and started; secondly, the cement system has good strength characteristics which meets strength requirements of cementing construction; thirdly, the cement slurry has good thickening performance, fluidity energy, sedimentation stability, right angle thickening characteristics and less water loss so as to meetthe requirements of site construction; fourthly, the operation time and cost are saved and technical support is provided for cementing formation which is easy for leak and fluid channeling.

Description

technical field [0001] The invention develops a high-temperature-resistant thixotropic anti-channeling agent and a high-temperature-resistant thixotropic anti-gas channeling cementing slurry system containing it, which are suitable for high-temperature and high-pressure production layer cementing operations and belong to the field of oil and gas well cementing materials. Background technique [0002] With the development of modernization, the demand for energy in the world is increasing day by day. Under the condition that recoverable and easy-to-recover reserves of oil are decreasing, the exploration and development of oilfields has developed into oceans, complex formations, deep wells and ultra-deep wells. The oil and gas reservoirs in the western oilfields of my country and the South China Sea are basically located in the formation of about 6000 meters. The temperature of the bottom hole increases rapidly with the increase of the well depth, which brings many problems to t...

AI Technical Summary

Problems solved by technology

However, high temperature will easily cause functional admixtures to fail and cause cement stone strength to decline, the rheology and stability of cement slurry will change, the viscosity of cement slurry will decrease, and the gas channeling resistance will decrease, which will easily lead to gas channeling and prevent gas channeling.

②The pressure of the gas layer is high, and the safety window is narrow. In the wellbore that encounters the high-pressure gas layer, there are low-pressure easy-to-leakage or even fracture-cave type serious leakage layers. If the high-pressure gas layer is to be stabilized, there is a risk of leaking the low-pressure layer For example, marine reservoirs in Northeast Sichuan are mostly fractured carbonate gas reservoirs. Well Heba 1, after entering Feisan Member of the Lower Triassic Feixianguan Formation, experienced well kicks and lost circulation many times. Gas invasion occurs during well killing, and lost circulation occurs during well killing. For example, carbonate gas reservoirs in the Shunnan area are mostly of fracture-cavity type. Too high cement slurry density will lead to serious leakage of fracture-cavity reservoirs. Density cement slurry will cause low fluid column pressure in the well, which will lead to gas channeling, directly affect the bonding strength of cement stone, cause a decline in sealing quality, and eventually cause damage to the casing

Clay mineral thixotropic cement slurry systems often have the problem of weak thixotropy, which cannot well meet the needs of cementing to prevent leakage, and may cause difficulty in mixing cement slurry after prehydration, affecting on-site construction; Thixotropic cement slurry mainly passes calcium sulfate cement slurry and aluminum sulfate and ferrous sulfate cement slurry

Both calcium sulfate and aluminum sulfate can react to form calcium aluminum vanadium, which promotes the natural combination between cement particles, thereby forming a network or gel structure; when subjected to shearing, the formed structure is easily destroyed, but sulfates touch The thixotropic agent only forms a small amount of network or gel structure, so that the thixotropy of the cement slurry system is less improved, and the thixotropic performance of the cement slurry system is limited; the alkali metal carbonate thixotropic cement slurry is mixed after a certain period of time. It shows good thixotropy, which is beneficial to maintain the good pumpability of cementing in the early stage, but the controllability of delayed thixotropic time is not strong, and it cannot well avoid the construction safety caused by thixotropy when cementing operations at different well depths question

The thixotropic cement slurry system using transition metal elements such as zirconium and yttrium as cross-linking agent and the anti-leakage and anti-gas channeling thixotropic cement slurry system using titanium chelate as cross-linking agent can make cement obtain high adhesiveness in a short time. It is easy to obtain thixotropy in low-density cement slurry, but these two types of thixotropic agents are sensitive to temperature and have poor high temperature resistance; the thixotropy of using mixed metal layered hydroxide as crosslinking agent Cement slurry system, the thixotropic mechanism of the system is that the modified cellulose can be chelated with mixed metal layered hydroxide through hydroxyl, carboxyl, etc., and at the same time, the cement particles associate to form an overall spatial network structure, The network structure is destroyed when it is sheared. The system has strong thixotropy, but generally has a high water loss. At the same time, the thixotropic performance becomes poor under high temperature conditions.

[0005] At present, domestic research on thixotropic anti-gas channeling cement slurry systems is mainly aimed at medium and normal temperature conditions, but there is little research on thixotropic anti-gas channeling cement slurry systems under high temperature conditions

Images