In this experimental study, diverse water-soluble Fe(III) complexes were synthesized and employed to catalyze the aquathermolysis of heavy oil. A ternary reaction system comprising heavy oil, water, and methanol was established to facilitate the process. Viscometry, thermogravimetric analysis, DSC, and elemental analysis were utilized to thoroughly investigate the treated heavy oil. The findings reveal that, under optimal conditions of water, catalyst, and methanol dosage, the viscosity of heavy oil can be significantly reduced by up to 88.22% after reacting at 250 °C for 12 h. Notably, apart from viscosity reduction, the catalytic aquathermolysis also effectively removes heteroatoms such as sulfur, nitrogen, and oxygen, enabling in situ modification and viscosity reduction of heavy oil. This study demonstrates the potential of water-soluble Fe(III) complexes in enhancing the efficiency of heavy oil extraction and processing.

Wellbore instability caused by the hydration of shale formations during drilling is a major problem in drilling engineering. In this paper, the shale inhibition performance of polyhydroxy-alkanolamine was evaluated using an anti-swelling test, linear swelling test, wash-durable test and montmorillonite hydration and dispersion experiment. Additionally, the shale inhibition mechanism of polyhydroxy-alkanolamine was studied via Fourier transform infrared spectroscopy (FTIR), particle size, zeta potential, thermogravimetric analysis (TGA) and scanning electron microscopy (SEM). The results show that the use of polyhydroxy-alkanolamine (EGP-2) could result in a relatively lower linear swelling rate of montmorillonite, and the linear swelling rate of 0.3% EGP-2 is 26.98%, which is stronger than that of 4% KCl. The anti-swelling rate of 0.3% EGP-2 is 43.54%, and the shrinkage–swelling rate of 0.3% EGP-2 is 34.62%. The study on the inhibition mechanism revealed that EGP-2 can permeate and adsorb on the surface of montmorillonite. The rolling recovery rate of easily hydrated shale was as high as 79.36%, which greatly reduces the dispersion ability of water to easily hydrated shale. The results of this study can be used to maintain the stability of a wellbore, which is conducive to related research.

This study aimed to evaluate the inhibitory effect of a series of ammonium adipate solutions (AASs) by using the linear expansion test, thermogravimetric analysis (TGA), and particle size distribution analysis, and to examine the underlying inhibitory mechanism. A series of AASs was prepared from adipic acid and amines as small-molecule inhibitors of oil shale rock swelling. They were then evaluated by the bentonite linear expansion test. The best one, namely, AAS-8 (synthesized with adipic acid and tetraethylenepentamine in a ratio of acid group to amine group of 1:2), was evaluated in a water-based drilling fluid. The linear expansion test showed that the linear expansion rate of AAS-8 was the lowest (59.61%) when the concentration was 0.1%. The evaluation of the drilling fluid revealed that AAS-8 had a strong inhibitory effect on the swelling of hydrated bentonite particles in the water-based drilling fluid and was compatible with carboxymethyl cellulose (CMC) and modified starch. The inhibition mechanism of AAS-8 was investigated using TGA and particle size distribution analysis, which demonstrated that AAS-8 might enter the clay layer and bind the clay sheets together by electrostatic adsorption and hydrogen bonding.

This research aims to determine the brittleness index (BI) and engineering properties of limestone specimens. In addition, this study evaluates the effect of moisture on the developed models to predict the BI and shear wave velocity (Vs), based on the point load index (Is50), dry and saturated tensile strength (Ts-d and Ts-s), and porosity. Gaussian process regression (GPR), multilayer feed-forward neural network (MFFNN), and multiple linear regression (MLR) predictive models were utilized. Microscopic examination of the limestone specimens revealed that calcite is the predominant mineral. It was observed that samples with higher calcite content exhibited greater brittleness and strength properties while having lower porosity. The results obtained from the MLR analysis demonstrated that it is possible to accurately forecast the brittleness index (BI), as well as the dry and saturated shear wave velocities (Vs-d and Vs-s) at the specific sites under investigation. The moisture effect on developed models showed that Vs prediction in dry conditions (Vs-d) was less accurate compared to the saturated conditions (Vs-s). Conversely, the relationships developed for estimating the BI in dry conditions exhibited higher accuracy. The analysis of all model assumptions using MLR indicated that the models could be reliably utilized. However, the MFFNN and GPR methods were found to be more conservative in estimating these properties. Moreover, the study identified the best transfer function and training algorithm for predicting Vs and BI. The evaluation metrics, such as R2 and RMSE revealed that GPR demonstrated higher precision compared to MFFNN and MLR.

Heavy oil transportation has become a highly technical operation facing complex difficulties. One of the major difficulties in the pipeline transportation is the high viscosity that requires efficient and economical ways to deal with. The typical polymer viscosity reducers are a negative problem during oil refinement process for their chemical properties. The objective of this study is to seek small molecular compound, different from the traditional polymers, to reduce the viscosity of the crude oil. In this work, a spirocompound, 3,9-diphenyl-2,4,8,10-tetraoxa-spiro[5.5]undecane, was synthesized catalyzed by zeolite and modified zeolite, and the product was fully characterized by NMR, MS, and TG. Then, it was used as viscosity reducer for crude oil. The factors such as dosage and temperature on the viscosity behavior have been studied. The results showed a significant viscosity reduction at different temperature, and the most economical dosage is 500 ppm. The multiphenyl groups can interact with asphaltene byπ-πstacking, and the spirostructure can fix the stacking in different direction, which can prevent the agglomeration of wax crystals.