Experimental investigation of two-phase relative permeability of gas and water for tight gas carbonate under different test conditions

Currently, tight carbonate gas reservoir has received little attention due to few discoveries of them. In this study, gas–water two-phase relative permeability was measured under two different conditions: High Temperature High Pore Pressure (HTHPP – 80 °C, 38 MPa), as well as Ambient Condition (AC), using whole core samples of tight gas carbonate. Relative permeability curves obtained at HTHPP showed two contrary curve profiles of gas relative permeability, corresponding to the distinctive micro-pore structure acquired from CT-Scanning. Then, based on Klinkenberg theory and a newly developed slip factor model for tight sandstone, slippage effect under AC is calibrated and the overestimation of gas relative permeability prove up to 41.72%–52.34% in an assumed heterogeneity. In addition, relative permeability curves obtained at HTHPP switch to higher gas saturation compared to that under AC with the rock wettability change from water-wet to less water-wet. And the wettability alteration is believed to be caused by charge change on mineral surface

miR-22 has a potent anti-tumour role with therapeutic potential in acute myeloid leukaemia

MicroRNAs are subject to precise regulation and have key roles in tumorigenesis. In contrast to the oncogenic role of miR-22 reported in myelodysplastic syndrome (MDS) and breast cancer, here we show that miR-22 is an essential anti-tumour gatekeeper in de novo acute myeloid leukaemia (AML) where it is significantly downregulated. Forced expression of miR-22 significantly suppresses leukaemic cell viability and growth in vitro, and substantially inhibits leukaemia development and maintenance in vivo. Mechanistically, miR-22 targets multiple oncogenes, including CRTC1, FLT3 and MYCBP, and thus represses the CREB and MYC pathways. The downregulation of miR-22 in AML is caused by TET1/GFI1/EZH2/SIN3A-mediated epigenetic repression and/or DNA copy-number loss. Furthermore, nanoparticles carrying miR-22 oligos significantly inhibit leukaemia progression in vivo. Together, our study uncovers a TET1/GFI1/EZH2/SIN3A/miR-22/CREB-MYC signalling circuit and thereby provides insights into epigenetic/genetic mechanisms underlying the pathogenesis of AML, and also highlights the clinical potential of miR-22-based AML therapy

Study on Simulation Modeling and Approximate Synchronous Computation Technology for the Active Structural Stiffness Design

AbstractIn the past, structure design mainly adopted strength criterion. At the same time, many problems occurred due to structural stiffness deficiency. In order to resolve many practical problems resulted from structural stiffness in aircraft structure, and draw out structural potential better, the design idea of active structural stiffness, namely, the method of active structural stiffness design (ASSD) is put forward at the beginning of the structure design. For ASSD, there are three key factors should be considered, that is, stiffness criterion, simulation modeling and computation analysis. In this paper, stiffness criterion, which is important at the preliminary stage of structural design, will be researched; Simulation modeling adopts parametric modeling technology; computation analysis is based on engineering beam theory, which is compiled and embedded into CATIA to compute structural stiffness. Using simulation modeling and computation analysis technologies, ASSD can be achieved quickly and conveniently

Experimental Study on Dynamic Characteristics of Shut-In and Restart Process in Water Drive Strong Heterogeneous Oil Reservoir

The main purpose of this investigation is to study the dynamic characteristics of shut-in and restart process in reservoirs with high water cut and strong vertical heterogeneity. The physical model, which includes three layers with low, medium, and high-permeability from top to bottom, was made according to the similarity law. Water drive test, the first restart test, and the second restart test were conducted, respectively. Water cut, oil recovery, and saturation distribution of the remaining oil were obtained during the tests. On this basis, mechanisms of shut-in and restart process of the reservoir were analyzed. It is concluded that appropriate developing plan such as layering mining and cyclic waterflooding should be implemented for developing strong heterogeneity reservoirs. The shut-in and restart tests showed that closing the water-flooded layer is beneficial for enlarging the sweep volume. Besides, water cut of 98% does not mean the economic limits of waterflooding. Under the effect of capillary force and gravitational differentiation, oil and water will redistribute in the formation. The redistribution of the oil and water, the fluctuation of the pressure difference, and the rebuild of the flow path, which produce parts of the bypassed oil, are the main mechanisms of the recovery enhancement by shut-in and restart operation. It should be noted that the shut-in and restart process indeed prolongs the waterflooding development. However, simply replying on the oil and water distribution under static conditions cannot greatly enhance the oil recovery

Experimental investigation of two-phase relative permeability of gas and water for tight gas carbonate under different test conditions

International audienceCurrently, tight carbonate gas reservoir has received little attention due to few discoveries of them. In this study, gas–water two-phase relative permeability was measured under two different conditions: High Temperature High Pore Pressure (HTHPP – 80 °C, 38 MPa), as well as Ambient Condition (AC), using whole core samples of tight gas carbonate. Relative permeability curves obtained at HTHPP showed two contrary curve profiles of gas relative permeability, corresponding to the distinctive micro-pore structure acquired from CT-Scanning. Then, based on Klinkenberg theory and a newly developed slip factor model for tight sandstone, slippage effect under AC is calibrated and the overestimation of gas relative permeability prove up to 41.72%–52.34% in an assumed heterogeneity. In addition, relative permeability curves obtained at HTHPP switch to higher gas saturation compared to that under AC with the rock wettability change from water-wet to less water-wet. And the wettability alteration is believed to be caused by charge change on mineral surface

Diversity of scoring, ingenuity of striking, art of flying - conceptual and systematical identification of soccer scoring techniques

The terms of soccer scoring techniques (SSTs) used in practice and research have been remaining confusing; even dramatic, we still do not know how many SSTs available for the game. This scenario hinders not only the scientific studies on some unique SSTs but also the development of novel coaching methods for learning these SSTs. The current paper aims to bridge the gap by establishing a SST terminology system. The system is built based on goal repeatability, selected anatomical & biomechanical parameters, and analyses of 579 attractive goals from international professional tournaments. The results have revealed that there are 43 SSTs existed in current soccer practice. Some SSTs can be identified by preliminary parameters (i.e. anatomical parameters, the ball vertical position at the shot and the hit-point on the ball), but most of them need additional biomechanical examination on the movement control in frontal & transverse planes, jumping control, and trunk orientation at shots in order to identify uniquely. Further, the new SST terminology has disclosed that soccer attractiveness is linked to the diversity, ingenuity and artistry of shots. The most attractive type of scoring awaited by millions of spectators is aerial shots. Lastly, the most important contribution of the new SST terminology system is to help researchers and practitioners launch target-orientated studies that would provide a practical and convincing scientific coach-method, clear definitions, and means to reevaluate and improve SSTs in practice

One-part alkali activated slag using Ca(OH)2 and Na2CO3 instead of NaOH as activator: more excellent compressive strength and microstructure

In this paper, sodium carbonate and calcium hydroxide instead of sodium hydroxide used as composite activators, and slag are applied to prepare one-part alkali-activated slag. Furthermore, the properties of the slag activated by sodium hydroxide are compared. The compressive strength, XRD, TGA, MIP, and SEM analysis of the two systems are performed. The results show that the one-part alkali-activated slag prepared from sodium carbonate and calcium hydroxide has a superior compressive strength against the slag activated by sodium hydroxide. It is also found that the hydration speed of the sodium hydroxide activated slag is faster, and thus the higher compressive strength of the one-part alkali-activated slag is not caused by the hydration speed. The hydration of one-part alkali-activated slag produces a certain amount of calcium carbonate, resulting in a lower porosity in comparison with the slag activated by sodium hydroxide, which may be the reason for the better compressive strength of one-part alkali-activated slag

Experimental Investigation on the Effects of CO₂ Displacement Methods on Petrophysical Property Changes of Ultra-Low Permeability Sandstone Reservoirs Near Injection Wells

The petrophysical properties of ultra-low permeability sandstone reservoirs near the injection wells change significantly after CO2 injection for enhanced oil recovery (EOR) and CO2 storage, and different CO2 displacement methods have different effects on these changes. In order to provide the basis for selecting a reasonable displacement method to reduce the damage to these high water cut reservoirs near the injection wells during CO2 injection, CO2-formation water alternate (CO2-WAG) flooding and CO2 flooding experiments were carried out on the fully saturated formation water cores of reservoirs with similar physical properties at in-situ reservoir conditions (78 °, 18 MPa), the similarities and differences of the changes in physical properties of the cores before and after flooding were compared and analyzed. The measurement results of the permeability, porosity, nuclear magnetic resonance (NMR) transversal relaxation time (T2) spectrum and scanning electron microscopy (SEM) of the cores show that the decrease of core permeability after CO2 flooding is smaller than that after CO2-WAG flooding, with almost unchanged porosity in both cores. The proportion of large pores decreases while the proportion of medium pores increases, the proportion of small pores remains almost unchanged, the distribution of pore size of the cores concentrates in the middle. The changes in range and amplitude of the pore size distribution in the core after CO2 flooding are less than those after CO2-WAG flooding. After flooding experiments, clay mineral, clastic fines and salt crystals adhere to some large pores or accumulate at throats, blocking the pores. The changes in core physical properties are the results of mineral dissolution and fines migration, and the differences in these changes under the two displacement methods are caused by the differences in three aspects: the degree of CO2-brine-rock interaction, the radius range of pores where fine migration occurs, the power of fine migration

Formation damage due to asphaltene precipitation during CO

In order to quantitatively evaluate the pore-scale formation damage of tight sandstones caused by asphaltene precipitation during CO2 flooding, the coreflood tests and Nuclear Magnetic Resonance (NMR) relaxometry measurements have been designed and applied. Five CO2 coreflood tests at immiscible, near-miscible and miscible conditions were conducted and the characteristics of the produced oil and gas were analyzed. For each coreflood test, the T2 spectrum of the core sample was measured and compared before and after CO2 flooding to determine the asphaltene precipitation distribution in pores. It is found that, the solubility and extraction effect of the CO2 plays a more dominant role in the CO2-EOR (Enhanced Oil Recovery) process with higher injection pressure. And, more light components are extracted and recovered by the CO2 and more heavy components including asphaltene are left in the core sample. Thus, the severity of formation damage influenced by asphaltene precipitation increases as the injection pressure increases. In comparison to micro and small pores (0.1–10 ms), the asphaltene precipitation has a greater influence on the medium and large pores (10–1000 ms) due to the sufficient interaction between the CO2 and crude oil in the medium and large pores. Furthermore, the asphaltene precipitation not only causes pore clogging, but also induces rock wettability to alter towards oil-wet direction

Influence of Pore Structure and Solid Bitumen on the Development of Deep Carbonate Gas Reservoirs: A Case Study of the Longwangmiao Reservoir in Gaoshiti–Longnusi Area, Sichuan Basin, SW China

A variable sedimentary environment and accumulation process leads to a complex pore structure in deep carbonate gas reservoirs, and the physical properties are quite different between layers. Moreover, some pores and throats are filled with solid bitumen (SB), which not only interferes with reservoir analysis, but also affects efficient development. However, previous studies on SB mainly focused on the accumulation process and reservoir analysis, and there are few reports about the influence on development. In this paper, through scanning electron microscope analysis, SB extraction, gas flow experiments and depletion experiments, and a similar transformation between experimental results and reservoir production, the production characteristics of carbonate gas reservoirs with different pore structures were studied, and the influence of SB on pore structure, reservoir analysis and development were systematically analyzed. The results show that permeability is one of the key factors affecting gas production rate and recovery, and the production is mainly contributed by high-permeability layers. Although the reserves are abundant, the gas production rate and recovery of layers with a low permeability are relatively low. The SB reduces the pore and throat radius, resulting in porosity and permeability being decreased by 4.73–6.28% and 36.02–3.70%, respectively. With the increase in original permeability, the permeability loss rate decreases. During development, the loss rate of gas production rate is much higher than that of permeability. Increasing the production pressure difference is conducive to reducing the influence. SB also reduces the recovery, which leads to the loss rate of gas production being much higher than that of porosity. For reservoirs with a high permeability, the loss rates of gas production rate and the amount produced are close to those of permeability and porosity. Therefore, in the reservoir analysis and development of carbonate gas reservoirs bearing SB, it is necessary and significant to analyze the influence of reservoir types