Wastewater produced from polymer flooding in oil production features high viscosity and chemical oxygen demand because of the residue of high-concentration polymer hydrolysed polyacrylamide (HPAM). In this study, steel slag, a waste from steel manufacturing, was studied as a low-cost adsorbent for HPAM in wastewater. Optimisation of HPAM adsorption by steel slag was performed with a central composite design under response surface methodology (RSM). Results showed that the maximum removal efficiency of 89.31% was obtained at an adsorbent dosage of 105.2 g/L, contact time of 95.4 min and pH of 5.6. These data were strongly correlated with the experimental values of the RSM model. Single and interactive effect analysis showed that HPAM removal efficiency increased with increasing adsorbent dosage and contact time. Efficiency increased when pH was increased from 2.6 to 5.6 and subsequently decreased from 5.6 to 9.3. It was observed that removal efficiency significantly increased (from 0% to 86.1%) at the initial stage (from 0 min to 60 min) and increased gradually after 60 min with an adsorbent dosage of 105.2 g/L, pH of 5.6. The adsorption kinetics was well correlated with the pseudo-second-order equation. Removal of HPAM from the studied water samples indicated that steel slag can be utilised for the pre-treatment of polymer-flooding wastewater.
In water-injection development, water-sensitive oil deposits are prone to water injection pressure increase and water injection volume decrease, which makes it difficult to complete production and injection allocation. To solve this problem, on the basis of screening traditional anti-expansion unblocking agents, and combined with the performance evaluation of the formula and core experiment, a reasonable improvement scheme was proposed in this paper to develop a new type water-sensitive oil reservoir anti-expansion unblocking agent. The performance evaluation experiment shows that it has an applicable dissolution rate for oil rock samples and can dissolve inorganic salt scale; the anti-expansion rate is up to 90%; the core dynamic evaluation experiment shows that the core permeability can be increased more than double after the injection of the anti-expansion unblocking agent. The new type water-sensitive anti-expansion unblocking agent were used in 7 wells of the site, and all of them have a good effect of water injection pressure decrease and water injection volume increase.
In view of the situation that heavy oil well production fluid needs to be gathered and transferred by heating or with heat water to ensure the normal operation, a kind of cold transportation viscosity reducer was developed through the compounding of different types of surfactants and the screening of functional additives, which adapt to the oil well produced fluid without heating or watering gathering process, for saving energy, reducing consumption and increasing efficiency, while meeting the environmental needs. After on-site practical applications of 30 pipelines with different physical properties of crude oil, the average pressure of gathering pipelines dropped 1.3 Mpa, which has achieved good results. Application results show that the cold transportation viscosity reducer has strong adaptability and less usage, and it has no influence on demulsification, while having a high value of applications and a broad market prospect.
In view of the traditional inorganic cement-based material hydration shrinkage caused by the impact of performance defects range of application, applying the principle of doping dispersion and compact packing, a multistage resin composite ductile cement slurry system with different temperatures was constructed. The compatibility, thickening and mechanical evaluation tests were carried out to optimize the resin type, doping amount and method. The results show that the thickening of the composite system is controllable, and the addition of resin is beneficial to improve the elastic deformation, whereas easy to pile up if adding extra amounts, and the compressive strength reduced. At the same time, adding resin first is beneficial to disperse in the cement gap. Compared with cement-based materials, the compressive strength increased 7% to 13%, the elastic modulus decreased 10% to 15%, and the deformation capacity increased 14% to 22%. Field test shows that it has good sealing performance and remarkable effect of oil increasing and dewatering, which provides a new technical means for controlling casing leakage and ensuring its normal production.
This article demonstrates a method to make classification and dosing control for oil wells. To find the main factors that caused the corrosion and scaling in oil wells, water quality data of one oil production plant were made principal component analysis. Then the oil wells were divided into four types by using spss19.0 clustering analysis software according to the differences among main factors. Finally, wells dosing were applied in the field according to the classification. The effect is obvious, the corrosion inhibition rate can reach 70% above, and scale inhibition rate of calcium carbonate can reach 90% above. Costs savings of all the wells add up to 5390 thousands.
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