Oilfield Sewage Research Articles

Study on the Methods for Removing Sulfide Ion and Sulfate Radical from the Oilfield Sewage

Sulfide ion can reduce the viscosity of polymer solution. The higher the concentration of sulfide ion is, the greater the effect of viscosity on polymer is, and it directly affects oil recovery rate. Some methods for removing sulfide were studied by adding the oxidizing substances. Each method had certain effect on removing sulfide. The addition of hydrogenperoxide in the solution makes it faster to remove sulfide than flowing air in it, although the removal of sulfide is still not complete. This removal is quick when ozone takes part in, and it will spend much time with the increased volume of solution. The extent of removing sulfide was mainly related to the oxidability of removed substances. The stronger the oxidability of oxidizing substances was, the better the performance for sulfide removing was. In addition, part of sulfate radical in oilfield sewage could be removed by nanofiltration membrane. Removal efficiency of sulfate radical is about 50%. The probability may be avoided that sulfate radical was reduced into sulfide by the sulfate-reducing bacteria (SRB) in sewage. This method could radically reduce the presence of the reduction of sulfur in sewage, and it can reduce the corrosion of underground oil pipeline.

Friction and wear properties of UHMWPE/nano-MMT composites under oilfield sewage condition

A new stabilizer material ultra-high molecular weight polyethylene (UHMWPE) was reinforced with modified nano-montmorillonite (MMT) in different contents. Tribological properties of the materials, together with the polyamide (PA) material used as stabilizer for the purpose of comparison, were tested against a J55 steel counterfact on a reciprocating tribometer under oilfield sewage condition. The experimental conditions were a contact pressure 7.0 MPa, a stroke length of 15 mm, and a reciprocating frequency of 1 Hz. The results show that the 10 wt.% nano-MMT composite exhibits the lowest friction coefficient and the best wear resistance among all specimens; that furrow and larger area of brittleness break are dominant for the PA specimen, and that plowed scratches and abrasive wear are dominant for the 10 wt.% nano-MMT composite. The new material proves to be better than PA material when used as stabilizer materials.

Influence of alkyl group of imidazolinyl-quaternary-ammonium-salt on corrosion inhibition efficiency

The action between imidazolinyl-quaternary-ammonium-salt (IQAS) molecule and Fe atom was studied, and the influence of the alkyl group connected with N atom of imidazoline ring on corrosion inhibition efficiency was explored. Quantum chemical methods, HF/6–31 G and HF/Lan L2 dz, were applied successively to calculate the parameters such as front molecular orbit energy of IQAS I–IV and chemical adsorption for IQAS I–IV and Fe atom. The corrosion inhibition efficiency was measured with the weight loss method of carbon steel samples in acidic solution and oil field sewage. Based on the theoretical analyses and experimental results, it is concluded that N-Fe coordination bond is formed between IQAS molecule and Fe atom, corrosion inhibition efficiency is decreased in the following order (from large to small): IQAS IV, IQAS III, IQAS II, IQASI.