Permeability Saturation Research Articles

Method for predicting drying-wetting and scanning soil-water characteristic curves

A method for predicting drying-wetting and scanning soil-water characteristic curves (SWCCs) of a soil has been proposed, which mainly uses Fredlund and Xing’s SWCC function with the fitting parameters evaluated from the saturated permeability (ks), grain size distribution curve and plastic index (PI) of a soil. The usefulness of the method has been checked by applying it to three sets of test data from this study and seven sets of test data from the literature. Fair and acceptable predictions were obtained. It is suggested that the method can be used to approximately predict SWCCs of a soil in case there is no test data available.

Determining the Geotechnical Slope Failure Factors via Ensemble and Individual Machine Learning Techniques: A Case Study in Mandi, India

Landslide disaster risk reduction necessitates the investigation of different geotechnical causal factors for slope failures. Machine learning (ML) techniques have been proposed to study causal factors across many application areas. However, the development of ensemble ML techniques for identifying the geotechnical causal factors for slope failures and their subsequent prediction has lacked in literature. The primary goal of this research is to develop and evaluate novel feature selection methods for identifying causal factors for slope failures and assess the potential of ensemble and individual ML techniques for slope failure prediction. Twenty-one geotechnical causal factors were obtained from 60 sites (both landslide and non-landslide) spread across a landslide-prone area in Mandi, India. Relevant causal factors were evaluated by developing a novel ensemble feature selection method that involved an average of different individual feature selection methods like correlation, information-gain, gain-ratio, OneR, and F-ratio. Furthermore, different ensemble ML techniques (Random Forest (RF), AdaBoost (AB), Bagging, Stacking, and Voting) and individual ML techniques (Bayesian network (BN), decision tree (DT), multilayer perceptron (MLP), and support vector machine (SVM)) were calibrated to 70% of the locations and tested on 30% of the sites. The ensemble feature selection method yielded six major contributing parameters to slope failures: relative compaction, porosity, saturated permeability, slope angle, angle of the internal friction, and in-situ moisture content. Furthermore, the ensemble RF and AB techniques performed the best compared to other ensemble and individual ML techniques on test data. The present study discusses the implications of different causal factors for slope failure prediction.

Method for measuring the saturated permeability coefficient of compacted bentonite at temperatures exceeding 100 °C

In deep geological repositories for high-level radioactive waste, the bentonite buffer layer is considered an important artificially engineered barrier between nuclear waste canisters and the host rock. Low permeability requirements of the bentonite must be met to prevent groundwater infiltration and radionuclide leakage. During the repository operation, gases will inevitably be generated through various physicochemical processes around the canister, and the continuous accumulation of these gases will result in a high-pressure state in the repository. In addition, the bentonite buffer layer may experence temperatures exceeding 100 °C because of the continuous release of decay heat from the nuclear waste in the canister, which can also affect the permeability of the bentonite buffer layer. Hence, it is necessary to obtain the saturated permeability coefficient of compacted bentonite at temperatures exceeding 100 °C. However, the conventional methods fail to consider the pressure effect, because when the temperature exceeds 100 °C under standard atmospheric pressure, free water will boil violently to form steam, which hinders the measurement of the saturated permeability coefficient of bentonite. Therefore, an innovative measurement method for the saturated permeability coefficient of compacted bentonite at temperatures exceeding 100 °C was proposed in this study, based on the relationship between the boiling point of water and the pressure. As the boiling point was increased by raising the pressure, the saturated permeability coefficients at 25 °C and 105 °C were sequentially measured for the same compacted bentonite specimen with the dry density of 1.65 g/cm3 to verify the feasibility of the proposed method. The results at 25 °C showed that the difference between the permeability coefficients measured by the proposed method and the conventional method was no more than 1 × 10−13 m/s. Thus, the proposed method can be applied to measure saturated permeability coefficients at temperatures exceeding 100 °C. Furthermore, the results at 105 °C indicated that it was more reasonable to calculate the permeability coefficients according to the amount of water seepage at the outlet. The proposed method can provide technical support for future studies on the effect of temperatures exceeding 100 °C on permeability and allow evaluation of the long-term performance of bentonite buffer layers in deep geological repositories.

In-series sample methodology for permeability characterization demonstrated on carbon nanotube-grafted alumina textiles

In-plane permeability of small area (100 × 50 mm) alumina fiber woven fabrics grafted with aligned carbon nanotubes (CNT) was quantified by placing them in series with a glass mat of known permeability during a flow experiment. The methodology was first validated on a reference woven textile. Permeability values matched those obtained by a direct method within a margin of ±15%. Permeabilities of radial-aligned (short CNT, SCNT) and so-called ‘Mohawk’ (long CNT, LCNT) morphologies of the CNT-grafted samples were then measured and compared to the non-grafted alumina, showing a decrease attributed to a change in local textile structure as assessed in previous studies. Unsaturated permeability decreased by 77% after SCNT- and 88% after LCNT-grafting, while saturated permeability further decreased by 90% and 93%, respectively. The high ratio of unsaturated to saturated permeability (in the range of 1.14 – 2.89) implies that capillary wicking contributes largely to the impregnation of CNT-grafted fabrics.

Guar Gum-Based Hydrogels as Potent Green Polymers for Enhanced Oil Recovery in High-Salinity Reservoirs.

Improving oil production for high-salinity reservoirs using polymer flooding is challenging due to chemical and mechanical degradations. This study developed two biodegradable biopolymers based on graft copolymerization of guar gum (GG) with two different co-monomers, which are acrylamide (Am) and 2-acrylamido-2-methylpropane sulfonic acid (AMPS), and cross-linked by N,N′-methylene bisacrylamide (MBA) to face these challenges. The newly synthesized guar gum-based hydrogels, GG-g-poly(Am-AMPS) (GH) and GG-g-poly(Am-AMPS)/Biochar (GBH composite), were evaluated as potential candidates for enhanced oil recovery (EOR) under high-salinity conditions. Fourier transform infrared (FTIR) spectroscopy and thermogravimetric analysis (TGA) of the synthesized hydrogels were investigated, and their rheological properties were measured at room temperature. Both GH and GHB display a shear-thinning performance. In polymer flooding experiments, guar gum hydrogel (GH) and guar gum/biochar composite hydrogel (GHB) showed a remarkable influence on delaying the water breakthrough and proved to be effective biopolymers for enhanced oil recovery in high-salinity reservoirs. At the optimum concentration of 5 g/L, GH flooding achieved maximum oil recoveries of 70.53 and 72.11% in secondary and tertiary recovery processes, respectively. Meanwhile, the waterflooding process achieved an ultimate oil recovery of 58.42%. GHB flooding at optimum concentration, 2 g/L, increased the amount of oil recovery by 8.95% in tertiary recovery compared to waterflooding. Furthermore, GH (5 g/L) and GHB (2 g/L) slightly enhanced the rock water wettability as confirmed by contact angle measurements for GH and the relative permeability saturation curves for GH and GHB.

Exploring the saturated permeability of remolded loess under inorganic salt solution seepage

The seepage of remolded loess with inorganic salt solutions can deteriorate its engineering properties. To gain insight into the mechanism responsible for changes in the permeability of remolded loess due to the invasion of inorganic pollutants, the saturated permeability tests were performed on remolded loess samples using deionized water (DW) and NaCl, CaCl2, AlCl3, and NaHCO3 solutions. Leaching tests were designed to determine the chemical components of leachates. Zeta potentials were measured to evaluate the electrochemical properties, and mercury intrusion porosimetry (MIP) and scanning electron microscope (SEM) tests were used to estimate changes in microstructure before and after seepage. The results indicate that the saturated hydraulic conductivity (Ksat) was positively correlated with the cation valence. With the increase of cation valence, the compression degree of double diffusion layer on the surface of clay particles increases, and a larger space for free water movement is formed. The salt effect promoted the dissolution of carbonate minerals of loess and enhanced permeability, for example, NaCl; while the common-ion effect of HCO3− inhibited their dissolution and even led to the calcite precipitation. In addition, the hydrolysis of Al3+ also significantly affected Ksat. Therefore, under the seepage of inorganic salt solutions, the order of Ksat of remolded loess samples was NaHCO3 < DW < NaCl < CaCl2 < AlCl3.

Static Measurements Enhance Saturation and Permeability Interpretation

This article, written by JPT Technology Editor Chris Carpenter, contains highlights of paper SPE 202683, “Marrying the Static and Dynamic Worlds: Enhancing Saturation and Permeability Interpretation Using a Combination of Multifrequency Dielectric, Nuclear Magnetic Resonance, and Wireline Formation Testers,” by Hassan Mostafa, Ghassan Al-Jefri, SPE, and Tania Felix Menchaca, SPE, ADNOC, et al., prepared for the 2020 Abu Dhabi International Petroleum Exhibition and Conference, Abu Dhabi, held virtually 9–12 November. The paper has not been peer reviewed. Accurate water saturation evaluation and permeability profiling are crucial factors in determining volumetrics and productivity of multiple, stacked carbonate reservoirs offshore Abu Dhabi and derisking reservoir management. The case study presented in the complete paper illustrates how the integration of static measurements, such as dielectric dispersion and nuclear magnetic resonance (NMR) with dynamic measurements improves understanding of reservoir properties and supports more-accurate reservoir evaluation. Sampling and downhole fluid analysis (DFA) performed by wireline formation tester (WFT) identifies the fluid and rock properties in various flow units. Field Background and Challenges Optimal field development requires accurate estimations of water saturation and permeability. In this greenfield, the hydrocarbon is generally oil (medium to light) with very low asphaltene content. Overall, the reservoir quality is controlled by a combination of depositional environment, sequence stratigraphy, and diagenesis. Some reservoirs have good porosity, but reconciliation of log-based water saturation results with well-test results has been an issue. The objective in this case study was to drill a pilot hole for data gathering in a poorly characterized field location. Phase I included drilling a hole with a 55° deviation to cover all reservoirs for data gathering only, with the openhole reservoir section then being plugged and abandoned. Phase II of the plan was to sidetrack and complete the well as dual water-injector boreholes. In the reservoir section of the pilot borehole, a variety of logs was acquired for evaluation, including both logging-while-drilling and wireline measurements. While drilling, triple- combination data were acquired, consisting of gamma ray, resistivity, and nuclear logs (density neutron) along with resistivity images. The wireline-logging program was carried out in two stages to avoid differential sticking. In the first stage, the WFT was used to acquire 10 pressure points, seven points in the first reservoir and three points in the second. Two DFA stations were also recorded in Zone 1 to confirm whether the oil/water contact was deeper than expected. Logging was conducted using a high-tension wireline cable, which facilitates quicker accessibility to the openhole sections. In the second stage, multiple wireline runs were performed for the formation evaluation of the complete section, followed by the WFT pressure and fluid-sampling run on the drillpipe conveyance. Another critical challenge was to obtain accurate water saturations in the heterogeneous, minor, thin reservoirs, which are bounded by dense layers above and below and cause shoulder-bed effects. The third challenge in this well was to obtain an accurate, continuous, and representative permeability profile for the multiple reservoirs. WFT mini-drillstem test (DST) stations along with NMR logs were used to address this important requirement.

Seepage and Dynamic Characteristics of Carbonaceous Mudstone Coarse-Grained Soil Embankment with Different Gradations

This study investigates the seepage and deformation characteristics of carbonaceous mudstone coarse-grained soil embankment with different gradations under the action of dynamic load and rainfall. An indoor geotechnical test is conducted, and the mechanical parameters of carbonaceous mudstone coarse-grained soil with different gradations are analyzed. A numerical calculation model of seepage and dynamic characteristics of carbonaceous mudstone coarse-grained soil embankment is established on the basis of the test data. The different effects of rainfall infiltration and vehicle load are evaluated. The seepage, settlement, and slope stability evolution characteristics of graded carbonaceous mudstone coarse-grained soil embankment slope are studied. Results show that under the condition of the same rainfall time, the greater the nonuniformity coefficient, the faster the decrease in pore water pressure of the coarse-grained soil embankment at the same monitoring point. The seepage velocity vector in the embankment is concentrated below the soil shoulder. The smaller the saturated permeability coefficient and saturated water content, the larger the seepage velocity vector. The greater the nonuniformity coefficient, the larger the coarse-grained soil embankment under vehicle load. The smaller the embankment settlement, the lower the safety factor of embankment. The safety factor decreases slowly at first and then decreases rapidly in the whole study period under the effect of dynamic wetting. The research results provide a theoretical reference for the practical engineering application of carbonaceous mudstone coarse-grained soil embankment in rainy areas.

Moisture Distribution during Water Absorption of Ordinary Portland Cement Mortars Obtained with Low-Field Unilateral Magnetic Resonance.

Moisture distribution in cement-based materials is important from the durability point of view. In the present study, a portable three-magnet array with an elliptical surface radio frequency coil was used to undertake magnetic resonance measurements of moisture content in ordinary Portland cement mortar and concrete samples. Measurements along the length of the samples during capillary water absorption produced moisture content profiles that were compared with reference profiles acquired using a magnetic resonance imaging instrument. Profiles obtained with the three-magnet array were similar in shape and in penetration depth to those acquired with magnetic resonance imaging. The correlation coefficient between the moisture content measured with both techniques was r2 = 0.97. Similar values of saturated permeability of the mortars with identical w/c ratio were computed with the Hydrus 1D software based on the moisture content profiles. Additionally, inverse Laplace transformation of the signal decays provided the water-filled pore size distribution in saturated and unsaturated regions of the samples. The three-magnet array was successfully used to acquire nuclear magnetic resonance signal from a concrete sample, which was not possible with the magnetic resonance imaging instrument using the single-point imaging technique.

Permeability characteristics and structural evolution of compacted loess under different dry densities and wetting-drying cycles.

Permeability characteristics of compacted loess is always an important topic in soil mechanics and geotechnical engineering. This study explored the permeability characteristics of compacted loess under different dry densities and wetting-drying cycles, and found that as the dry density increases, the compacted loess surface became denser, the saturation permeability coefficient and saturation infiltration rate decreased. However, the wetting-drying cycle presented the opposite result. Meanwhile, the evolution of the microstructure was investigated by Scanning Electron Microscope (SEM) and Nuclear Magnetic Resonance (NMR) to explain the change of its permeability characteristics. The size of compacted loess aggregates was quantitatively analyzed by Image-Pro Plus (IPP) software. It showed that the size of compacted loess aggregates for different dry densities were concentrated from 10–100 μm, occupying 65.0%, 58.19%, and 51.64% of the total aggregates area respectively. And the interesting finding was that the area occupied by 10–50 μm aggregates remained basically unchanged with the number of wetting-drying cycles increasing. Therefore, the size of 10–50 μm aggregates represented the transition zone of compacted loess. NMR analyses revealed that with increasing dry density, the volume of macropores in the compacted loess rapidly decreased, the volume of mesopores and small pores increased. Meanwhile, the change in micropores was relatively small. The pore volume of the compacted loess after three wetting-drying cycles increased by 8.56%, 8.61%, and 6.15%, respectively. The proportion of macropores in the total pore volume shows the most drastic change. Variations in aggregate size and connection relationships made it easier to form overhead structures between aggregates, and the increased of macropore volume will form more water channels. Therefore, the change in permeability characteristics of compacted loess is determined by aggregate size, loess surface morphology, and the total pore volume occupied by macropores.

Development of medium-frequency cavity loaded with multi-ring magnetic alloy cores cooled by chemically inert liquid

Magnetic alloys (MAs) are commonly applied in the radio-frequency (RF) cavities of proton synchrotrons. The high saturation permeability and Curie temperature of MAs facilitate the development of RF cavities with large accelerating gradients that could not be achieved with ferrite. The conventional MA core is a disk-shaped toroid made by winding MA ribbons. Here, we propose a multi-ring core structure that consists of three concentrically arranged toroidal ring cores of different radial sizes. Neither epoxy resin impregnation nor a waterproof coating is applied to the cores, and thus the thermal stress during high-power operation is expected to be relaxed. A set of multi-ring cores is sandwiched between two glass-epoxy plates with flow channels. This modular structure increases the velocity of the coolant flow, making the flow turbulent to obtain the desired cooling efficiency. Coolant-induced corrosion of the Fe-based MA is prevented by adopting a low-viscosity, chemically inert, and electrically insulating liquid. The RF and thermal designs of a cavity loaded with multi-ring cores are presented and two types of test cavity are developed. A series of high-power tests demonstrate stable operation with the designed performance. The results of experimental performance tests for two cavities loaded with multi-ring MA cores cooled by a chemically inert liquid are reported.

Hydro-mechanical response of crushed argillite and bentonite mixtures as sealing material

Mixture of excavated Callovo-Oxfordian (COx) argillite and MX80 bentonite has been proposed as potential sealing material for the French deep geological disposal facility of radioactive waste. The mixtures hydro-mechanical behaviour was studied in order to assess their response on design requirements. At the as-compacted state, soil fabric analysed by the MIP technique, showed single-modal pore distribution for pure COx and bimodal pore distribution for samples containing MX80. All tested mixtures developed homogeneous behaviour during compaction with no effect of MX80 presence. Swelling potential was evaluated by hydration tests under 4 MPa on highly compacted material (2.0 Mg/m 3 ). Swelling increase and saturated permeability reduction was obtained on bentonite content increment. Combining results of the present experimental work and remarks of previous researchers, the characteristic saturation potential slope was determined and exploited to estimate the swelling under 1, 4 and 7 MPa for various COx/MX80 mixtures compacted at different pressures. The experimental verification of the adopted method suggested an approach of identifying possible combinations in terms of compaction and bentonite content that can fulfill design requirements. • Mixtures compressibility at initial water content is governed by COx argillite. • Bentonite presence results in bimodal pore size distribution. • Saturation potential slope estimates swelling under varied stresses for OC samples.

Determination of Unsaturated Hydraulic Properties of Seepage Flow Process in Municipal Solid Waste

The unsaturated hydraulic characteristics of waste soil are an essential basis for predicting and evaluating leachate migration and distribution in landfills. The saturated water content and permeability coefficient were measured, and a multi-step drainage monitoring experiment was conducted indoors at different dry densities, particle sizes, and degradation ages. Single and dual permeability models were adopted to determine the unsaturated hydraulic characteristic parameters of waste. Results show that dry density and particle size are the key factors affecting the saturated water content and permeability of waste. A single degradation age has little effect on it. Respectively, the saturated water content has a linear relationship with dry density, and permeability has an exponential relationship with dry density under limited experimental data. The overflow numerical inversion method can accurately obtain the unsaturated hydraulic characteristic parameters of wastes and summarizes the values of the unsaturated hydraulic characteristic parameters of wastes with different attributes in the literature and the results of this study. The dual-permeability model performed significantly better than the single-permeability model for water movement, suggesting that a dual-domain description is required for water flow in landfills.

Chemical Transport in Partially Saturated Rocks

We have conducted single- and two-phase pulse-tracer experiments in a Berea Sandstone core using the N2/water system. X-Ray Computed tomography (CT) and Positron Emission Tomography (PET) were used to obtain the three-dimensional distribution of the nonwetting phase saturation and to image the transport of a radiotracer within the sample, respectively. Experiments were carried out at two different levels of residual saturation, so as to assess the impact of water content on solute dispersal. We observe that the solute plume is largely influenced by the level of residual gas saturation and by its spatial distribution. The latter is determined by the distribution of the nonwetting phase prior to imbibition and, ultimately, by the hysteretic behavior of the capillary pressure curve. While previous observations have unequivocally demonstrated the role of capillary pressure heterogeneity in local saturation development during drainage, our results indicate that the same is true for the subsequent imbibition and trapping process. This generates a complex interplay between saturation distribution, permeability heterogeneity, and pore-water velocity, with potential implications on the achieved rate of dissolution of the injected CO2 in geologic carbon sequestration applications.

Effects of bacterial activity on the saturated hydraulic conductivity of remolded loess

Loess is widely used as a construction material in engineering projects on the Loess Plateau of China but is regarded as one of the most problematic soils due to water sensitivity. Hydraulic conductivity ( K ) is an essential parameter in assessment of water transfer in porous media. However, the influence of bacterial activity on the saturated permeability of remolded loess is still unclear and rarely being studied. We systematically studied the effects of Gram-negative bacterial activity (a common bacteria in the loess region) on the hydraulic properties of remolded loess, with the aim to better understand water flow through loess. A series of laboratory experiments were conducted to identify the variation in hydraulic conductivity under various bacterial inoculation and carbon constraint conditions. The results indicated that the K was relatively stable (0.14–0.16 m/d) at the initial phase and decreased by 81–93% reaching 0.01–0.05 m/d at the end of the experiments. The variation of hydraulic conductivity can be divided into the unaffected stage, linear reduction stage and stable stage. The growth of bacteria and the accumulation of extracellular polymeric substances occupied the pores between soil particles in the sample, which reduced the porosity and lead to the decrease of K . Higher available carbon contents and greater initial inoculum sizes speeded up the process of hydraulic conductivity reduction. The delayed effect was observed between rapid decline of hydraulic conductivity and exponential growth of bacteria. It should be highlighted that the reduction of hydraulic conductivity in the soil columns was mainly dependent on clogging in the inlet layer. Our findings provide a better insight into the change of hydraulic conductivity related to bacterial activities, and promote the reorganization of water cycle uncertainty and the prevention of engineering geological disasters in loess areas. • Saturated hydraulic conductivity decreased by 81–93% due to bacterial activities. • Delayed effect between linear reduction of hydraulic conductivity and exponential growth of bacteria. • Reduction of hydraulic conductivity is mainly due to bacterial growth in inlet layer.

Modeling of relative permeabilities including dynamic wettability transition zones

Wettability is a pore-scale property that impacts the relative movement and distribution of fluids in a porous medium. There are reservoir fluids that provoke the surface within pores to undergo a wettability change. This wettability change, in turn, alters the dynamics of relative permeabilities at the Darcy scale. Thus, modeling the impact of wettability change in the relative permeabilities is essential to understand fluids interaction in porous media. In this study, we include time-dependent wettability change into the relative permeability–saturation relation by modifying the existing relative permeability function. To do so, we assume the wettability change is represented by the sorption-based model that is exposure time and chemistry dependent. This pore-scale model is then coupled with a triangular bundle-of-tubes model to simulate exposure time-dependent relative permeabilities data. The simulated data is used to characterize and quantify the wettability dynamics in the relative permeability–saturation curves. This study further shows the importance of accurate prediction of the relative permeability in a dynamically altering porous medium.

Investigating and predicting the temperature effects of permeability for loess

Temperature is one of the key factors affecting the permeability of water flow in loess, influencing its stability and, consequently, its geohazard potential. The traditional temperature calibration formula(TTCF) is widely used in the literature for calculating the permeability at some temperature, based on the permeability at 20 °C. However, its suitability has not been verified, especially for water flow in loess. The influence of temperature on the permeability of loess and the suitability of the TTCF were examined using samples of the late-Pleistocene Malan loess, the most widely distributed loess in the Chinese Loess Plateau, as the subject. The temperature dependency of the saturated permeability of remolded loess was investigated using the constant head permeability test method over a temperature range of 0 to 40 °C. The results show that the permeability of remolded loess increases with temperature, but in a nonlinear manner. Between 0 and 4 °C, although the changes are small, and at around 25 °C, there may be an important change in the soil's structure. We found that the measured values of loess permeability deviate strongly from those calculated by the TTCF, especially over the temperature range 0 to 4 °C and > 25 °C. New formulas for the calibration of temperature effects on the permeability of loess have subsequently been developed. Also, an empirical model for predicting the saturated hydraulic conductivity was inferred, which can satisfactorily reflect the temperature and compactness effects on permeability. The results of this study may be employed for projecting the effects of temperature changes into loess engineering and in assessing geohazard potential.

Characteristics of tuff breccia-andesite in diverse mechanisms of landslides in Oita Prefecture, Kyushu, Japan

Heavy rainfall frequently occurred in Kyushu and triggers the landslides every year. This study observes the landslides which occurred in Oita Prefecture, Kyushu, Japan. The landslides in this study, consisting of the same soil materials, tuff breccia and andesite materials; however, the landslide mechanisms were different. Two landslides occurred caused by heavy rainfall in the different timing of the landslide occurrence, and another landslide occurred without the heavy rainfall or an earthquake occurs. Therefore, this study aims to analyse the physical and mechanical properties of tuff breccia and andesite materials with diverse landslide mechanisms. This study performed soil stratigraphic analysis and soil hardness measurements in the field, and performed physical properties, saturated permeability, mechanical properties, and XRD tests in the laboratory. This study found that characteristics of tuff breccia and andesite in diverse mechanisms of landslides were not very different, especially on the landslides caused by heavy rainfall. Furthermore, the landslide in the andesite and tuff breccia areas could be divided into three types based on the timing of the landslide occurrence, scale of the landslide, and landslide mechanisms.

Effects of ammonium ion and bentonite content on permeability of bentonite-clay mixture

Sanitary landfill is a common method for the treatment of municipal solid waste. The landfill leachate contains a large amount of NH4+, which will affect the physicochemical properties of bentonite, and subsequently change the anti-seepage function of the bentonite enhanced cutoff wall. The permeability tests were carried out on bentonite-clay mixed soil infiltrated by the ammonium salt solutions using a head pressure control permeameter. The results show that saturated permeability coefficient of the bentonite-clay mixture increases with the decrease of bentonite content and with the increase of NH4+ concentration. Moreover, the reasonable mass content of bentonite is about 10% if the studied bentonite-clay mixture are used in vertical cutoff wall. The scanning electron microscope (SEM) and the nuclear magnetic resonance (NMR) measurements were conducted on the bentonite-clay mixed soil samples with different bentonite contents, and samples infiltrated by the ammonium salt solutions with different concentrations, and afterwards the variations of the micro pore structure and pore-size distribution were obtained. Connecting the Donnan osmotic pressure with saturated permeability of bentonite-clay mixed soils, the effect mechanism of bentonite content and ammonium solution concentration on the permeability of the bentonite-clay mixture was analyzed.

Analysis of logging parameter model of Jurassic complex reservoir in Xinjiang Shenquan Oilfield

The study discusses the characteristics of Jurassic reservoir in Shenquan Oilfield in Xinjiang. The reservoir of Qiketai Sanjianfang formation mainly develops delta front facies and shore shallow lake facies sand bodies.The lithological characteristics of the reservoir are mainly fine sandstone and siltstone, and the physical properties of the target layer are mainly medium porosity and medium permeability. The Jurassic reservoir space in Shenquan Oilfield is sandstone pore type, mainly composed of secondary pores, mainly including intergranular dissolved pores, intragranular dissolved pores and intercrystalline pores, with good connectivity between pores. According to the analysis data of well logging, core analysis, production performance and DST in Shenquan Oilfield, porosity, permeability and water saturation models are established respectively:The porosity interpretation model is established by using acoustic wave and shale content; the permeability parameter interpretation model is realized by applying graph based cluster analysis method and neural network algorithm. The oil saturation interpretation model is obtained by Archie formula. According to the logging interpretation model and interpretation results, it can meet the needs of reservoir evaluation, oil-water distribution and original geological reserve parameters. After analyzing the logging parameter model and reservoir parameter calculation method, it is considered that the Jurassic in the Shenquan Oilfield in Xinjiang has better physical properties.