Optimizing the Production of LNG and NGL from Arab Crudes and Wet Gases

Natural Gas Liquids (NGL) refer to a mixture of gases that consist mostly of ethane, propane, butane and pentane. The other term which closely related to NGL is Liquified Natural Gas (LNG) which refers to methane and traces of ethane. These products can be extracted by multi-stages of compression and cooling. In addition of being the main feedstock of any petrochemical industry, NGL and LNG are used widely in the industrialized countries as a major source of energy. It is expected that their future role in both the international energy market and the petrochemical industry will continue its historical gradual growing trend.This paper presents the mathematical formulation of an economic model that was developed to optimize the production of LNG and NGL. The objective function of the model is to maximize the net cash flow return of selling LNG and NGL. The explanatory variables of the model are LNG and NGL volumes and prices, oil volume and prices, the initial costs of separators, chillers, demethanizer, compressor, partial condenser and boiler, the running cost which includes cost of refrigerants, cost of steam and other continuous operating and transportion cost. The developed model should be utilized as a useful tool to help the design of an efficient processing of natural gases. A great deal of the unlimited what if questions can be answered using this model. This paper also presents a flow sheet of the natural gas processing model. Each section of the proposed production system is presented schematically. The mathematical formulation of the computation techniques used in each section are given along with all the equation derivations

Factors Affecting Sand Production from Unconsolidated Sandstone Saudi Oil and Gas Reservoir

In this work a physical model has been constructed to simulate sand production from oil and gas reservoirs. The model can accommodate unconsolidated as well as consolidated sandstone cores. The experiments were designed to investigate the effect of confining pressure, flow rate, and the displacing fluid viscosity on sand production mechanism in unconsolidated sandstone formations. Saline water (3.5% NaCl by weight), light (35° API) and heavy (27° API) crude oils were used as displacing fluids in the tests. The main goal of this study was to examine if controlling of the production rate alone can solve the problem of sand production in a Saudi oil reservoir. The oil reservoir is situated in an unconsolidated sandstone formation. A produced sand sample was obtained from this reservoir. Tests were conducted on sand packs having a similar granulomere distribution to that of the reservoir.The experimental results showed that, the magnitude of sand production from the tested porous medium is strongly affected by both flow rate and confining pressure. Sand production decreases with increasing confining pressure and/or decreasing flow rate. Only very fine particles of the porous medium are produced at high confining pressures. When water, or low viscosity crude oil are saturating the porous medium, sand production problem can be managed by controlling the flow rate. In case of saturating the porous medium by heavy crude oil, sand production mechanism becomes different and therefore, controlling only the flow rate cannot stop sand production. Hence, alternative sand control measures must be applied to control sand production in heavy crude oil reservoirs such as down hole emulsification, gravel packing, screen liners, or down hole consolidation

Evaluate the Toxicity of Pyrethroid Insecticide Cypermethrin before and after Biodegradation by Lysinibacillus cresolivuorans Strain HIS7

Herein, bacterial isolate HIS7 was obtained from contaminated soil and exhibited high efficacy to degrade pyrethroid insecticide cypermethrin. The HIS7 isolate was identified as Lysinibacillus cresolivuorans based on its morphology and physiology characteristics as well as sequencing of 16S rRNA. The biodegradation percentages of 2500 ppm cypermethrin increased from 57.7% to 86.9% after optimizing the environmental factors at incubation condition (static), incubation period (8-days), temperature (35 °C), pH (7), inoculum volume (3%), and the addition of extra-carbon (glucose) and nitrogen source (NH4Cl2). In soil, L. cresolivuorans HIS7 exhibited a high potential to degrade cypermethrin, where the degradation percentage increased from 54.7 to 93.1% after 7 to 42 days, respectively. The qualitative analysis showed that the bacterial degradation of cypermethrin in the soil was time-dependent. The High-Performance Liquid Chromatography (HPLC) analysis of the soil extract showed one peak for control at retention time (R.T.) of 3.460 min and appeared three peaks after bacterial degradation at retention time (R.T.) of 2.510, 2.878, and 3.230 min. The Gas chromatography–mass spectrometry (GC–MS) analysis confirmed the successful degradation of cypermethrin by L. cresolivuorans in the soil. The toxicity of biodegraded products was assessed on the growth performance of Zea mays using seed germination and greenhouse experiment and in vitro cytotoxic effect against normal Vero cells. Data showed the toxicity of biodegraded products was noticeably decreased as compared with that of cypermethrin before degradation