A gas migration law study of a large-scale 3D physical similarity simulation with an adaptive Kalman filter algorithm

Purpose In this study, a physical similarity simulation plays a significant role in the study of crack evolution and the gas migration mechanism. A sensor is deployed inside a comparable artificial rock formation to assure the accuracy of the experiment results. During the building of the simulated rock formation, a huge volume of acidic gas is released, causing numerous sensor measurement mistakes. Additionally, the gas concentration estimation approach is subject to uncertainty because of the complex rock formation environment. As a result, the purpose of this study is to introduce an adaptive Kalman filter approach to reduce observation noise, increase the accuracy of the gas concentration estimation model and, finally, determine the gas migration law. Design/methodology/approach First, based on the process of gas floatation-diffusion and seepage, the gas migration model is established according to Fick’s second law, and a simplified modeling method using diffusion flux instead of gas concentration is presented. Second, an adaptive Kalman filter algorithm is introduced to establish a gas concentration estimation model, taking into account the model uncertainty and the unknown measurement noise. Finally, according to a large-scale physical similarity simulation platform, a thorough experiment about gas migration is carried out to extract gas concentration variation data with certain ventilation techniques and to create a gas chart of the time-changing trend. Findings This approach is used to determine the changing process of gas distribution for a certain ventilation mode. The results match the rock fissure distribution condition derived from the microseismic monitoring data, proving the effectiveness of the approach. Originality/value For the first time in large-scale three-dimensional physical similarity simulations, the adaptive Kalman filter data processing method based on the inverse Wishart probability density function is used to solve the problem of an inaccurate process and measurement noise, laying the groundwork for studying the gas migration law and determining the gas migration mechanism.

The investigation of the average diameter of the SiO2 nanoparticles effect on the oil displacing efficiency from the pore in the rock formation using nanosuspension as a displacing agent

The numerical investigation of the nanofluid flow, which displaced the oil, in a microchannel was carried out. The effect of the average diameter of the SiO2 nanoparticles on the oil displacing efficiency by nanofluids for different sizes of microchannel at various Reynolds numbers was studied. A T-shaped microchannel with a vertical channel, called a pore channel, which imitated the pore in the rock formation was considered as a computational domain. The main flow channel width and height were 200 µm. The width and height of the pore channel were varied in the range from 100 µm to 800 µm. The Reynolds number varied from 0.1 to 100. The oil recovery coefficient, which is defined as the ratio of the displacing volume of oil from the pore to the volume of the pore was considered as the main studied characteristic. The nanofluid is considered a single-phase fluid with experimentally obtained properties. The mass concentration of SiO2 nanoparticles was 0.5%. The average diameters of nanoparticles were 5 nm, 18 nm, and 50 nm. It was found, that the oil recovery coefficient increased with a decrease in the average diameter of nanoparticles. It was obtained that the nanofluid can enhance the oil recovery several times compared to pure water.

Assessment of Tube Well Pumping Test Performance on Different Geological Formation

Water supply-demand is increasing in line with the increment in population. Natural water resources are declining due to reduction of water catchment areas, river pollution and drought. This causes the raw water quantity and quality to decrease and increase water treatment costs. Groundwater usage may be able to solve this problem due to its less polluted nature which requires less treatment. The groundwater is preserved in aquifer within the geological formations, i.e., in the alluvium and fractured-rock. However, the groundwater yield of each formation is unknown unless tube well is constructed and pumping test are performed. This study aim to evaluate the tube well performance via pumping test on two different geological formations. This research focuses on the effect of transmissivity, hydraulic conductivity, and efficiency of the aquifer, which are step-drawdown test, constant-rate test and recovery test in tube well in geological formation of alluvium and fractured rock. Three well-pumping tests at each formation were conducted at IBS Universiti Malaysia Kelantan (UMK), Kelantan, Sekolah Kebangsaan Chantum, Kelantan, Sekolah Menengah Kebangsaan Agama Tok Bachok, Kelantan, FRU Wakaf Tapai, Terengganu, Kampung Dada Kering, Kuala Lipis, Pahang, and Kampung Seri Gunung Pulai, Johor, respectively. The aquifer efficiency obtained from the relationship between transmissivity and hydraulic conductivity. The suggested value of 75% efficiency is selected to present the well’s efficiency. The wells efficiency indicate that the alluvium formation has roughly uniform output between 9.39m3/h, 11.23m3/h and 23.38m3/h. Meanwhile in the fractured rock formation the efficiency was highly varied between sites, the highest is 32.33m3/h and the other two sites obtained has low output of 3.44 m3/h and 1.00m3/h respectively. The alluvium aquifer showed uniform water production compared to fractured hard rock aquifer. Meanwhile the water quantity in the fractured hard rock formation is unpredicted, which subjected to the fractured rock characteristic.

METASOMATIC CHANGES IN ROCKS OF SEDIMENTARY COMPLEXES IN THE CARPATHIAN OIL AND GAS PROVINCE AS AN INDICATOR OF CARBOHYDRATE MIGRATION

A field and laboratory investigation of sedimentary rocks in Carpathian oil and gas province was curried out. The theoretical and practical aspects of the peculiarities of the development of metasomatic process during the migration of fluids at the postsedimentation stage of rock formation were investigated. Based on detailed field researches, a consistent pattern of mineral aggregates’ and their crystalloid individuals developing was defined. The arguments for developing a new geochemical model of oil deposits indication in Carpathian oil and gas province were provided.

Rock Thickness Identification by XGBoost with Logging Data

Based on research on the response mechanism of rock formations and reservoirs to logging curves, 12 logging curves selected by combining the depth characteristics of formations are proposed to identify rock formations and reservoirs using four algorithms: logistic regression (LR), support vector machine (SVM), random forest (RF) and XGBoost. Out of 60 wells in the study block, 57 wells were selected for training and learning, and the remaining 3 wells were used as prediction samples for testing the algorithm. The recognition of rock formations and reservoirs is performed by each of these four machine learning algorithms, and predictive knowledge is obtained separately. It was found that the accuracy of the 4 algorithms for rock formation and reservoir layer identification reached over 90%, but the XGBoost algorithm was found to be the best in terms of the 4 scoring criteria of F1-score, precision, recall and accuracy. The accuracy of rock formation identification could reach over 95%, and the correlation analysis between the logging curve and rock formation could be performed on this basis. The results show that the RMN, RLLD and RLLS have the most obvious responses to the sandstone layer, off-surface reservoir and effective thickness layer, and the CAL has the least effect on the formation and reservoir identification, which can provide an effective reference for the selection and dimensionality reduction of the subsequent logging curves.

Disaster and Risk Mitigation at The Toll Road Planning Stage

PT. Hutama Karya (Persero), according to Presidential Regulation No. 100 of 2014 and No. 117 of 2015, obtained an assignment to construct and operate 24 sections of Trans Sumatera Toll Road along 2,789 km, including Padang - Pekanbaru Toll Road, where almost all of the segments are located in fault areas and in areas with diverse rock formation. In terms of the number of fault locations, the toll road has a greater risk of earthquakes. Whereas in terms of varying rock formations, construction planning and improper structure determination will cause a highly cost-enhancing effect. In the planning stage, the selection of route is one of the mitigations to minimize the risks and impacts of the earthquake disaster. Toll road trajectories are designed optimally by considering the movement of the earth’s plates based on fault data on these locations and data on rock formations for the construction and structure plan of the Toll Road. Input data needed is Geological Secondary Data and Topographic Data containing information on fault areas and rock formations. Therefore, planning with Quantm Trimble software is the right solution. Determining the route with Quantm Trimble software is one of the effective and efficient methods. The main key in determining routes by Quantm Trimble is the software algorithm which can determine the route quickly by considering the main constraints such as avoiding fault areas, avoiding an area with certain rock formations also determining the construction methods on certain rock formation areas. Quantm Trimble software is able to generate several alternative routes based on user-defined constraints, including accommodating the automatic selected smoothing process according to the specified road geometry standard. The software greatly accommodates the determination of the plan by considering risk and disaster management, as well as being able to manage costs well by determining the construction method plan quickly and accurately.

The investigation of the efficiency of oil displacing from the pore in the rock formation depending on the width and height of the pore using nanosuspension as a displacing agent

The numerical investigation of the two-phase fluid flow in a microchannel was carried out. The effect of the pore width and height on the oil displacing efficiency by nanofluids for various Reynolds numbers was studied. The computational domain was a T-shaped microchannel with a horizontal main flow channel and a vertical channel that imitated the pore in the rock formation, called a pore channel. The main channel width and height were 200 µm, and the pore channel width and height were varied in the range from 100 µm to 800 µm. The Reynolds number was varied from 0.1 to 100. The main studied characteristic was the oil recovery coefficient, defined as the ratio of the volume of oil remaining in the pore to the volume of the pore. That characteristic, obtained for a case, when the nanofluid was used as a displacing agent, was compared to the similar one obtained for a case, when pure water was used as a displacing agent. A single-phase fluid with properties, determined experimentally, was considered the nanofluid. The mass concentrations of SiO2 nanoparticles were 0.25% and 0.5%. The average diameter of nanoparticles was equal to 5 nm. It was found, that the oil recovery coefficient increased with an increase in width of the pore channel and a decrease in its height. It was obtained that the nanofluid can enhance the oil recovery in several times as compared to pure water. It was also found that the main factor affecting the efficiency of oil recovery is the contact angle of wetting.

In situ stress characteristics of the NE Sichuan basin based on acoustic emission test and imaging logging

This study presents the distribution rule of in situ stress in the northeast Sichuan basin and its relationship with fracture. Sixty-seven sets of core samples of 21 Wells from the terrigenous clastic rock formation (Shaximiao, Qianfoya, Xujiahe) and marine carbonate formation (Jialingjiang, Leikoupo, Feixianguan) in the northeast Sichuan basin were tested by acoustic emission experiment. The in situ stress variation with the depth was established and the corresponding regression analysis was done. The horizontal principal stress direction of terrigenous clastic rock formation and marine carbonate rock formation was obtained by combining the dual diameter data of 6 wells and the imaging logging data of 3 wells. The results show that the vertical stress in the northeast of Sichuan basin has a linear relationship with the depth, and there is little difference between the vertical stress and the overburden weight of rocks. The maximum and minimum horizontal principal stress and horizontal shear stress increase with the burial depth. The divergence degree of horizontal shear stress with depth greater than 3000 m is greater than that of the stratum smaller than 3000 m. The horizontal stress plays a dominant role in the northeast Sichuan basin. With the increase in depth, the influence of tectonic stress field decreases and the vertical stress increases. Impacted by Dabashan and Qinling plate tectonic movement, the direction of in situ stress in marine carbonate strata is nearly east–west. The direction of maximum horizontal principal stress in terrigenous clastic rock formation is basically northwest–southeast. The imaging logging data show that the fracture direction is consistent with the horizontal principal stress direction, and the present in situ stress direction is favorable to the secondary reconstruction of natural fractures, and the fractures keep good opening. The distribution law of in situ stress in northeast Sichuan basin shows σH > σV > σh, indicating that the fault activity in this area is dominated by strike-slip type, the tectonic stress field is dominated by horizontal tectonic stress, in addition that the stress state is conducive to reverse fault activity.

Residual Water Saturation of Source Rocks of the Bazhenov Formation Western Siberia, Russia

The article presents a new method of determining the residual water saturation of the Bazhenov Rock Formation using synchronous thermal analysis which is combined with gas IR and MS spectroscopy. The efficiency of the extraction-distillation method of determining open porous and residual saturation in comparison with the developed method which are considered in detail. Based on the results of studies in the properties of the Bazhenov Rock Formation, a significant underestimation of the residual water saturation in the existing guidelines for calculating reserves was found, and the structure of the saturation of rocks occurred to be typical for traditional low-permeability reservoirs. The values of open porous and residual water saturation along the section of the Bazhenov Formation vary greatly, which also contradicts the well-established opinion about the weak variability of the rock properties with depth.