Study On Slow Release Characteristics And Application Conditions Of Anti - Scaling Agent For Anti - Scaling

Currently, water flooding is one of the most important exploitation methods in oilfields, which inevitably leads to scaling. Serious scaling problem can not only negatively affect the production of crude oil, but also cause environmental pollution problems at some level. This research focuses on the squeezing inhibitor treatment technology, which avoids the disadvantages of the traditional scale inhibition methods. However, the traditional laborotary researches do not represent the real condition in the oilfield, so it is necessary to develop new methods for the squeezing inhibitor treatment technology for optimization and improvement.In this thesis, the present commonly-used scale inhibition methods in oilfields were introduced based on the origination of scaling, the formation and identification of scale,and harm. The classification of the antiscaling agent and scale inhibitors were elaborated. As a kind of scale inhibitor, low molecular weight sodium polyacrylate was synthesized at different conditions. The synthetic products were evaluated by the compatibility test and the dynamic loop test. As a result, the optimal synthesis condition of low molecular weight sodium polyacrylate was determined, and the scale inhibitor R showed the best performence in the dynamic loop tests between the five products.The performence of scale inhibitors under turbulent condition and the adsorption /desorption of scale inhibitors are two key parts of squeezing inhibitor treatment technology. For the turbulent condition part, a newly developed test methodology with rotating cylinder has been applied to generate high shear rate and evaluate surface deposition with Reynolds numbers up to-34000. The relationship between Reynolds number and surface deposition is addressed. Using this highly representable test method for BaSO4 scale deposition, several different generic types of inhibitor chemistries including polymers and phosphonates, were assessed under different levels of turbulence to evaluate their performance on surface deposition. The results showed it is not always true that higher turbulence results in higher dose of inhibitor being requested to control scale. It is inhibitor chemistry and mechanisms dependent. The scale inhibitors can be classified as three types when evaluating the trend of mass deposition versus Reynolds number and the morphology of the crystals deposited on the metal surface. For the adsorption/desorption part, a new sand pack methodology which provides a better simulation of field squeezing treatments than traditional corefloods has been designed to provide a better understanding of the scale inhibitor retention mechanisms when polyquaternary amines are applied in pre-flush treatments. The result provides an understanding on the effects of polyquaternary amines on squeeze lifetime for both phosphonate and polymeric scale inhibitors. The new sand pack methodology can provide more precise results and better repeatability.Based on the analysis of the scale and the water in Weizhou 12-1 oilfield, conventional tests and core damage experiments were implemented to select the scale inhibitor and the squeeze life enhancer which can suit the oilfield. The dosage of chemicals were determined by the research of parameters in the squeezing inhibitor treatment, and the procedures through construction process were detailed. The evaluation and monitoring of the whole squeezing inhibitor treatment technology for Weizhou 12-1 oilfield were completed.