Determination of phase-partitioning tracer candidates in production waters from oilfields based on solid-phase microextraction followed by gas chromatography-tandem mass spectrometry

Conductivity Evaluation of Horizontal Wells in Coalbed Methane Reservoirs: Applicability of Micromaterial Tracer Testing Technology

Horizontal well-staged fracturing technology is widely used in the exploitation of coalbed methane reservoirs. Most coalbed methane wells have little or no flowback fluid after fracturing due to strong adsorption in the reservoir. The fracture conductivity of each fracturing interval can only be evaluated in the water drainage and gas production stage. Traditional chemical tracer monitoring technologies are risky to operate and do not provide accurate qualitative measurements. The potential applicability of trace material tracer testing technology in coalbed methane reservoirs has theoretical and practical significance, as does establishing a set of fracturing tracer technologies (e.g., reagent systems, construction schemes, detection interpretation) suitable for coalbed methane horizontal wells. Geological, laboratory, and field test data are used in this study to preliminarily resolve the trace material tracer adsorption problem in the coalbed by improving the chemical agent formula. The proposed method is applied to determine the conductivity of a fractured section in a coalbed methane well.

Head-Space SPME for the Analysis of Organophosphorus Insecticides by Novel Silica IL-Based Fibers in Real Samples

This work demonstrates the suitability of a newly developed ionic liquid (IL)-based silica SPME fiber for the determination of seven organophosphorus insecticides in cucumber and grapefruit samples by headspace solid-phase microextraction (HS-SPME) with a gas chromatography−flame ionization detector (FID). The sol-gel method released four different sorbent coatings, which were obtained based on a silica matrix containing ILs immobilized inside its pores. In order to obtain ionogel fibers, the following ionic liquids were utilized: 1-Butyl-1-methylpyrrolidinium bis(trifluoromethylsulfonyl)imide; Butyltriethyl ammonium bis(trifluoromethylsulfonyl)imide; 1-(2-Methoxyethyl)-3-methylimidazolium bis(trifluoromethylsulfonyl)imide, and 1-Benzyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide. The developed fibers were applied for the extraction of seven different insecticides from liquid samples. The most important extraction parameters of HS-SPME coupled with the GC-FID method were optimized with a central composite design. The new SPME fiber demonstrated higher selectivity for extracting the analyzed insecticides compared with commercially available fibers. The limit of detection was in the range of 0.01−0.93 μg L−1, the coefficients of determination were >0.9830, and 4.8−10.1% repeatability of the method was found. Finally, the obtained ionogel fibers were utilized to determine insecticides in fresh cucumber and grapefruit juices.

Unraveling the Complex Composition of Produced Water by Specialized Extraction Methodologies

Produced water (PW), a waste byproduct of oil and gas extraction, is a complex mixture containing numerous organic solubles and elemental species; these constituents range from polycyclic aromatic hydrocarbons to naturally occurring radioactive materials. Identification of these compounds is critical in developing reuse and disposal protocols to minimize environmental contamination and health risks. In this study, versatile extraction methodologies were investigated for the untargeted analysis of PW. Thin-film solid-phase microextraction with hydrophilic-lipophilic balance particles was utilized for the extraction of organic solubles from eight PW samples from the Permian Basin and Eagle Ford formation in Texas. Gas chromatography-mass spectrometry analysis found a total of 266 different organic constituents including 1,4-dioxane, atrazine, pyridine, and PAHs. The elemental composition of PW was evaluated using dispersive solid-phase extraction followed by inductively coupled plasma-mass spectrometry, utilizing a new coordinating sorbent, poly(pyrrole-1-carboxylic acid). This confirmed the presence of 29 elements including rare earth elements, as well as hazardous metals such as Cr, Cd, Pb, and U. Utilizing chemometric analysis, both approaches facilitated the discrimination of each PW sample based on their geochemical origin with a prediction accuracy above 90% using partial least-squares-discriminant analysis, paving the way for PW origin tracing in the environment.

Evaluation of the Release Mechanism of Sustained-Release Tracers and its Application in Horizontal Well Inflow Profile Monitoring

The inflow profile is an important parameter to evaluate horizontal well productivity; however, quantitative interpretation of the inflow profile of the horizontal wells both accurately and cost-effectively is a common challenge faced by horizontal well production technology. The sustained-release chemical tracer is a new low-cost, long-lasting, and simple technique for monitoring the inflow profile in horizontal wells. In this study, a new type of sustained-release tracer is developed using bisphenol A-type epoxy resin as the polymer matrix and 2,6-difluorobenzoic acid, 3,4-difluorobenzoic acid, and 2,3,4,5-tetrafluorobenzoic acid as tracers. Meanwhile, the release mechanism and the influencing factors (chemistry of the tracer, temperature, salinity, and flow rate) of the sustained-release tracer are studied experimentally. The experimental results show that the release mechanism of the sustained-release tracer can be divided into two stages. The first stage involved the erosion process, in which the fluid gradually contacts and wraps the tracer, and the release rate is very fast. The second stage included the diffusion process, which is the diffusion-dissolution process once the fluid is completely wrapped around the tracer, and the release rate of this process is slow. The temperature is directly proportional to the release rate of the tracer, whereas salinity is inversely proportional to the release rate, and the fluid velocity does not affect the release rate. Finally, three kinds of sustained-release tracers are applied in the field, and a method to interpret the inflow profile of the sustained-release tracer is proposed. The result of application indicates that the sustained-release tracer developed in this study can efficiently monitor the inflow profile of the horizontal well.