Hydrophobic gel composite cement and plugging method thereof

Abstract

The invention discloses hydrophobic gel composite cement, and relates to the technical field of cement slurry plugging in petroleum drilling. The composite cement comprises the following components in percentage by weight: 0.15 to 0.25 percent of hydrophobic gel, 10 to 30 percent of hydrophobic curing agent, 8 to 15 percent of coagulant, and the balance of cement. The invention provides a preparation method for the composite cement at the same time. By introducing the hydrophobic gel into a cement system, the water repellency of the cement slurry system is improved, the strength of a plugginglayer is improved, the mixing alternation of stratum water and cement slurry can be effectively inhibited, the tendency of gradual enhancement along with the time after the composite cement is injected into a leakage layer is ensured, the pressure bearing capacity of the leakage layer is improved, the loss problem of a loss return leakage well is solved, and the one-time plugging success rate is improved and exceeds 50 percent.

Description

technical field [0001] The invention relates to the technical field of cement slurry plugging in oil drilling, in particular to a hydrophobic gel composite cement and a plugging method suitable for lost-return leakage in the Luohe Formation in the Longdong block. Background technique [0002] The buried depth of the Jurassic Luohe Formation in Changqing Xifeng Oilfield is 700-1100m, the underground temperature is between 28-35°C, and vertical and horizontal fractures are developed. The water is relatively active, and conventional bridge plugging, cement slurry plugging, etc. are easily diluted and dissolved by formation water, and the plugging effect is poor, time-consuming and material-consuming, affecting the construction progress, and the one-time success rate of plugging is less than 50%. : [0003] 1. The rigidity of the plugging material is insufficient [0004] All bridge plugging materials currently used cannot reach the curing rigidity of concrete, and are almost ...

AI Technical Summary

Problems solved by technology

[0002] The buried depth of the Jurassic Luohe Formation in Changqing Xifeng Oilfield is 700-1100m, the underground temperature is between 28-35°C, and vertical and horizontal fractures are developed. The water is relatively active, and conventional bridge plugging, cement slurry plugging, etc. are easily diluted and dissolved by formation water, and the plugging effect is poor, time-consuming and material-consuming, affecting the construction progress, and the one-time success rate of plugging is less than 50%. :

[0003] 1. The rigidity of the plugging material is insufficient

[0004] All bridge plugging materials currently used cannot reach the curing rigidity of concrete, and are almost ineffective for large cracks or extra-large malignant cracks;

[0005] 2. Existing plugging materials lack adhesion to rocks and have insufficient hydraulic erosion resistance

[0007] 3. Insufficient rigidity and strength of gel plugging

[0008] Although chemical gel has many advantages, such as: better pumpability, delayed crosslinking, late gelation, water repellency, rock adhesion, overall tensile capacity (tension) and compressive capacity (elasticity), etc., but the lack of congenital composition (solid content <10%) restricts the performance of its overall comprehensive rigidity

[0009] 4. Defects of cement injection plugging process

[0011] ②The cured cement plug layer has only rigid strength, and lacks "flexibility" under the action of mechanical stress, and may be fractured again by the exciting pressure of the drilling fluid in the wellbore