An environment-friendly high temperature and salt resistant calcium modified natural polymer fluid loss reducer

Abstract

The invention relates to an environment-friendly high temperature and salt resistant calcium modified natural polymer fluid loss reducer. Its technical solution is: it is made of the following components, by mass percentage: 20%-30% of modified starch, 3%-8% of partially hydrolyzed polyacrylamide, 3%-5% of aluminum citrate, and 10% of superfine calcium carbonate %‑20%, the balance is water. Beneficial effects are: the present invention is aimed at the downhole complex situation of high-temperature deep well drilling, especially the brine layer, salt rock layer, salt-gypsum layer, and gypsum-mud layer. High temperature and salt-resistant calcium fluid loss reducer is the key to improving the wall-building ability of drilling fluid; the product prepared by the present invention has outstanding fluid loss reducing effect, strong wall-building, temperature resistance up to 150°C and above, salt resistance to saturation, Resistant to 0.5% CaCl 2 . The product has good compatibility with other treatment agents, is non-toxic and environmentally friendly, and can also be used as a protection material for drilling fluid oil and gas layers.

Description

technical field [0001] The invention relates to a fluid loss reducer for drilling fluid and completion fluid, in particular to an environment-friendly, high temperature, salt and calcium modified natural polymer fluid loss reducer. Background technique [0002] Drilling fluid is the working fluid in the oil drilling process. Fluid loss and wall-building is one of the most basic properties of drilling fluids. The main factor affecting the wall-building performance of fluid loss is the quality of the drilling fluid filter cake. A high-quality filter cake has the characteristics of thin thickness, good density, high toughness and good lubricity. The compressibility of the filter cake is the key to determining the quality of the filter cake. important factor in compressibility. Therefore, the key to the control of drilling fluid filtration and wall-building is to maintain a certain amount of fine particles that can be fully hydrated in the drilling fluid. In water-based drill...

AI Technical Summary

Problems solved by technology

Under the conditions of high temperature and high salinity in drilling fluid, the hydration effect of fluid loss control agent in drilling fluid is greatly weakened, the solubility is reduced, and then the adsorption effect on the surface of clay particles is weakened, and the dehydration effect on the surface of clay particles is consequently reduced. The hydration layer on the surface of clay particles becomes thinner, which leads to a decrease in the irreducible water content of the mud cake, and a weakening of the compressibility of the mud cake, which eventually makes the compactness of the mud cake worse, the fluid loss increases, and the drilling fluid fluid loss creates a wall. deterioration, affecting the normal progress of drilling construction

[0003] At present, high temperature resistant fluid loss reducers (such as lignite resin products) have poor resistance to salt and calcium, while salt and calcium resistant fluid loss reducers (such as conventional modified starch products) have low temperature resistance; Fluid loss reducers (such as modified asphalt products) that are resistant to salt and calcium at high temperatures have high toxicity and poor environmental protection performance, which seriously restricts the normal operation of drilling operations in high-temperature deep wells and high-salt conditions