Technical Evaluation of the Consequence of HCDP Upsets From Gas Producers Along Pipeline Laterals

Natural gas accepted into the pipeline at receipt points is subject to gas quality specifications to ensure that downstream laterals and mainlines are not subjected to operational upsets, and that the integrity of the pipeline and related facilities is not compromised. One of the specifications is the maximum hydro-carbon dew point (HCDP) at the pipeline operating pressure. Occasionally, gas plants encounter operational upsets that result in a higher HCDP. If the HCDP exceeds the ground temperature, condensation of heavier hydrocarbon can potentially occur along the lateral. Ideally, after an upset has been detected and the producer has been shut in, the lateral would be pigged to remove the condensed hydrocarbons. However, if the lateral is unpiggable, the only way to remove the liquids is to evaporate them into a flow of dryer gas. The present paper compares two potential courses of action which may be taken after a high HCDP is detected at a receipt point on an unpiggable line: (a) flowing dry gas from the producer after the source of upset is corrected, or (b) pulling dryer gas back from the operator’s mainline through the lateral to the producer. In order to determine the most appropriate course of action for a given upset, the state of the lateral during and after the upset must first be accurately quantified. In the present paper, the state was modelled based on the governing equations of fluid flow including heat transfer and condensation, the GERG-2008 equation of state, and empirical liquid-hold-up equations. The effect of flow parameters (e.g., gas composition, lateral elevation profile, ground temperature, etc.) on the upset severity is explored. Subsequently, models for forward flow and pull back are presented, and the criteria for selecting when either course of action is appropriate are discussed.

Acetylene oligomerization on the surface of TiO2: a step forward in the in situ synthesis of nanostructured carbonaceous structures on the surface of photoactive oxides

In situ acetylene oligomerization allows synthesis of polycyclic condensed hydrocarbons in close contact with the TiO2 surface. These products represent intermediate steps in the production of photoactive graphene-like layers on TiO2.

DEPOSITION OF PETROLEUM HEAVY ORGANIC COMPOUNDS ON A LOW CARBON STEEL TUBING

Reduction of petroleum wells production is often observed and related to the presence of solid deposits adhered on the internal wall of the tubing. A piece of tubing with organic material adhered on its surface was recovered from a Mexican southeastern region well. Its composition and morphology was studied applying scanning electron microscopy with X-ray energy dispersion spectroscopy (SEM-EDXS), X-ray diffraction (XRD) and reflection Fourier Transform Infrared Spectroscopy (FT-IRS). High-condensed hydrocarbons with hydroxyl and carboxyl functional groups and 6.4 wt% total sulfur were found. The adhered-material morphology suggests vitreous solid structure usually identified in polycyclic aromatic compounds. Iron (II, III) oxides and nonstoichiometric sulfides are present; the last, as a corrosion product obtained in petroleum with low H 2 S concentration. Pyrrhotite ( Fe 1-x S ), which exhibits a nonstoichiometric structure, was reported as the active phase of iron oxide catalysts in hydrogen interchange processes.

An investigation of the formation of molecular complexes of O-(3,5-dinitrobenzoyl)-O-acetylcellulose with n- and π-donors

Soluble O-(3,5-dinitrobenzoyl)-O-acetylcellulose was synthesized, and the formation of molecular complexes with n- and π-donors was investigated. The formation of complexes obeys the Langmuir adsorption isotherm adjusted for macromolecules. The formation of molecular complexes with low-molar mass compounds of the type of heterocyclic compounds, aromatic amines and condensed hydrocarbons was confirmed by electric resistance measurements. The largest decrease in the specific resistance by 2-3 orders of magnitude was observed with indole and phenothiazine, while the specific resistance of the other types of donors decreased by 1-2 orders of magnitude. A decrease in the activation energy took place with all types of complexes.