Influence of Water Injection Pressure and Method on Oil Recovery of Water Injection Huff and Puff in Tight Volcanic Oil Reservoirs.

The water injection huff and puff (WIHP) technology is regarded as one of the important means to improve the recovery factor (RF) of tight volcanic oil reservoirs (TVORs), but the influence of water injection pressure (WIP) and water injection method (WIM) on the oil recovery effect of WIHP has been rarely reported. In this paper, we first collected the real full-diameter cores from a TVOR and then simulated the distribution characteristics of fractures and matrix pores after hydraulic fracturing of the reservoir through the combination and cutting of the cores. Finally, we used the large-sized physical simulation device for tight oil WIHP that can bear high temperature and high pressure and a nuclear magnetic resonance instrument to conduct experiments of five cycles of constant pressure WIHP (CWIHP) with WIPs of 25, 32.5, and 40 MPa and step-by-step pressure rising WIHP (SWIHP) (the WIP was 25, 30, 33, 37, and 40 MPa in order) and obtained the liquid production law and mechanism of tight volcanic rock (TVR) under CWIHP and SWIHP. The result shows that under the CWIHP mode, the RF of TVR has a good power-law-positive correlation with the WIP. However, with the increase of WIHP cycles, the RF of CWIHP always decreases rapidly. In the WIHP of TVR, the injected water mainly collects oil in large pores (the pore radius is greater than 0.1 µm), and the closer the area to the outlet end of oil production and the higher the fracture density, the higher the RF. SWIHP can also effectively improve the RF of TVR, but compared with CWIHP with a WIP of 40 MPa, the amount of recovered oil decreases relatively slowly with the increase of WIHP cycles. In the first two cycles of the five cycles of WIHP, the RF of CWIHP was higher, but from the third cycle, the RF of SWIHP begins to be greater, and the more the number of cycles of WIHP, the more obvious the advantage of SWIHP. When the number of WIHP cycles exceeds 5, the oil recovery effect and the economy of SWIHP are better. This study can provide a solid theoretical basis for the efficient development of WIHP in TVORs.

The Law and Mechanism of the Sample Size Effect of Imbibition Oil Recovery of Tight Sedimentary Tuff.

Imbibition is an important mechanism to improve the recovery factor (RF) of a tight oil reservoir. Accurately evaluating the oil production capacity of tight oil reservoirs by imbibition is of great significance for the formulation of oilfield production plans and productivity prediction. However, there is currently no unified regulation on the selection of rock sample size in tight oil reservoir imbibition evaluation experiments, resulting in great differences in reservoir imbibition oil production capacity obtained from rock samples of different sizes, which brings great challenges to the efficient development of tight oil reservoirs. To clarify the law and mechanism of the rock sample size effect of tight core imbibition oil recovery, this paper takes the newly discovered tight sedimentary tuff (TST) oil reservoir as an example. First, several representative real cores were collected. Then, their wettability and pore structure characteristics were analyzed. Finally, physical simulation experiments of imbibition under different rock sample sizes were conducted. The results show that the TST has very favorable imbibition conditions, which are manifested in the following: (i) the wettability is weakly hydrophilic to hydrophilic; (ii) the mineral composition is tuffaceous minerals, calcite, and quartz, without clay minerals; (iii) micro-nanoscale pores are developed; and (iv) the pore throats are evenly distributed. In the imbibition experiments of rock samples of different sizes, the oil production characteristics of the core surface, the variation form of imbibition rate, pore production characteristics, and the influence mode of imbibition pressure on imbibition do not have the sample size effect. However, the RF of the spontaneous imbibition has an obvious sample size effect, and there is a good exponential function relationship between the imbibition RF and the specific surface area (SSA) of cores. The fundamental reason why the rock sample size effect of the TST imbibition oil recovery is relatively stable and has strong regularity is that its pore structure and wettability are relatively homogeneous and stable. The change of rock sample size does not have a great impact on the distribution of the core pore structure and wettability, resulting in no significant change in its imbibition power, resistance, and distance. Therefore, the main factor determining the imbibition RF of rock samples with different sizes is their SSA. The research results of this work can provide an important theoretical basis for understanding the law and mechanism of TST imbibition oil recovery and unifying the imbibition experimental results of small-sized rock samples.

Effect of Urolithin A on Bone Repair in Mice with Bone Defects.

BACKGROUND: Bone defect difficult to manage clinically and it is a big challenge to repair it. Secondary metabolites source from herb has shown potential for the treatment of bone defect. METHODS: Mesenchymal stem cells (MSCs) were isolated from mice and incubated with urolithin A (UA) (10, 25, and 50 µg/mL). 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) assay was performed to estimate apoptosis and mineralisation was evaluated by alkaline phosphatase assay and alizarin red S staining. A middle femoral defect was induced in mice and bone tissue was prepared for endochondral ossification by treating with UA. The effect of UA was estimated by determining markers of osteoblast proliferation in serum and micro-computed tomography to analyse bone defects. RESULTS: UA enhanced mineralisation of MSCs and osteogenic gene markers in MSCs in vitro. Also, the bone defect score and bone mineral density were improved by UA. Moreover, UA ameliorated the altered Wnt3a protein and histopathological changes in bone defect mice. CONCLUSION: Presented report conclude that UA enhances osteoblast proliferation in bone-defect mice by activating the Wnt pathway.

Pore Structure and Movable Fluid Characteristics of Typical Sedimentary Lithofacies in a Tight Conglomerate Reservoir, Mahu Depression, Northwest China.

The pore structure and movable fluid characteristics of tight conglomerate reservoirs are complex, which are greatly different from conventional reservoirs. The depositional mechanism is the fundamental factor controlling the physical properties of conglomerate reservoirs. However, there is a lack of systematic research on the pore structure and movable fluid characteristics of conglomerate reservoirs with typical sedimentary facies. This paper investigates the pore structure and movable fluid characteristics of conglomerate of different sedimentary facies based on various experiments. Casting thin sections, X-ray diffraction, scanning electron microscopy, high-pressure mercury injection, and nuclear magnetic resonance experiments were conducted on 32 conglomerates samples from the Mahu Sag, Junggar Basin, China. The quality classification method of tight conglomerate reservoirs is established. The results show that the conglomerate can be divided into three sedimentary facies; traction flow conglomerate (TFC) and pebbled sandstone (PSS) mainly develop intergranular pores and dissolved pores; and the pore diameter curves are mainly a double peak, single peak, and flat peak. Gravity flow conglomerate (GFC) mainly develops dissolved pores and interstitial micropores, and the pore diameter curve is mainly a single peak. PSS includes pebbled gritty sandstone (P(G)SS) and pebbled fine sandstone (P(F)SS). TFC and P(G)SS are favorable class I reservoirs, while GFC and P(F)SS are nonfavorable class II reservoirs. A new parameter, the ratio of the major axis to the minor axis of the pore outer ellipse (axial ratio), is proposed to quantitatively describe the compaction effect. The average axial ratios of the three lithofacies are 3.04, 3.98, and 8.78, respectively, indicating that the compaction is intensified and the pore structure becomes worse. By analyzing the correlation between pore structure parameters and permeability, it is found that the main controlling factors of permeability of GFC and TFC are sorting and connectivity, respectively, and the main flow radius is the most suitable parameter to describe permeability. A linear spectral decomposition method was used to establish a new quantitative calculation method of movable fluid saturation for different types of pores, and the results show that the movable fluid saturation of intergranular pores is the highest (average: 65.43%), and the movable fluid saturation of TFC and P(G)SS with more intergranular pores is the highest. Movable fluid saturation is inversely proportional to the content of I/S and the compaction rate and positively proportional to the content of quartz and feldspar and the cementation rate. The fluid mobility of water-wet samples is weaker. The research results provide theoretical support for the identification of favorable reservoirs and the cognition of a development mechanism.

Integrin α5ß1 promotes BMCs mobilization and differentiation to exacerbate choroidal neovascularization.

Choroidal neovascularization (CNV) is an acknowledged pathogenic mechanism of various ocular diseases, and in situ cells and mobilized bone marrow-derived cells (BMCs) are thought to participate in this process. We aimed to evaluate the roles of integrin α5 in BMCs and vascular endothelial cells (VECs) in the CNV process mediated by SDF-1/CXCR4 signaling. Adult wild-type mice were engrafted with whole BMCs obtained from GFP transgenic mice and then laser injured to induce CNV. BMCs and RF/6A cells were cultured to discover the mechanism of CNV in vitro. BMCs were mobilized to CNV areas, which expressed elevated SDF-1 and CXCR4. When SDF-1 was intravitreally injected, the number of BMCs was profoundly increased. In the SDF-1-treated group, the levels of integrin α5 expressed on BMCs and VECs were significantly higher than those on the cells in the control group. SDF-1 significantly increased the expression and positive ratio of integrin α5, which was involved in the recruitment and differentiation of BMCs into BMC-derived VECs, and these effects were suppressed by the CXCR4 inhibitor AMD3100. The PI3K/AKT pathway rather than the ERK pathway mediated SDF-1/CXCR4 induction of integrin α5. Integrin α5 suppression efficiently prevented the production of TGF-ß and bFGF but not VEGF. Inhibiting the SDF-1/CXCR4-PI3K/AKT-integrin α5 axis reduced CNV severity. Integrin α5 participates in BMC recruitment and differentiation in SDF-1/CXCR4-induced CNV and inhibition of this pathway may be a new approach to inhibit CNV.

Self-seeding circulating tumor cells promote the proliferation and metastasis of human osteosarcoma by upregulating interleukin-8.

Most circulating tumor cells (CTCs) die during the process of metastasis, but self-seeding CTCs can invade the primary tumor or form clinically meaningful metastases. This study aimed to evaluate the capacity of self-seeding CTCs to promote osteosarcoma growth and lung metastasis and to clarify the specific role of interleukin (IL)-8 in CTC self-seeding. We successfully isolated and cultured self-seeding CTCs through a self-seeding nude mouse model established using green fluorescent protein (GFP)-labeled F5M2 cells and found that self-seeding CTCs exhibit increased cellular proliferation, migration, and invasion in vitro, increased tumor growth and lung metastasis in mice, and increased IL-8 expression. Furthermore, suppressing IL-8 inhibited tumor growth and metastasis and reduced CTC seeding in primary tumors in vitro and in vivo. In osteosarcoma patients, IL-8 levels significantly correlated with the Enneking stage and metastasis. These findings demonstrate that self-seeding osteosarcoma CTCs can promote tumor growth and lung metastasis through IL-8. Their increased metastatic potential and elevated IL-8 expression suggest a novel strategy for future therapeutic interventions to prevent osteosarcoma progression and metastasis.

miR-640 aggravates intervertebral disc degeneration via NF-κB and WNT signalling pathway.

OBJECTIVES: Low back pain becomes a common orthopaedic disease today. It is mainly induced by the degeneration of the intervertebral disc. In this study, we tried to reveal the pathogenesis of the degeneration and the relative therapeutic strategy, which are still elusive. MATERIALS AND METHODS: We collected 15 degenerative intervertebral tissues and five healthy donors. Nucleus pulposus and annulus fibrosus cells were subcultured. miR-640 expression was determined by qPCR. Computer analysis and luciferase reporter assay were used to confirm miR-640 target genes. Immunohistochemical and immunocytochemical staining was used to trace the proinflammatory cytokines and key transductor of signalling pathways. We also used ß-galactosidase staining, flow cytometry, and cell viability assay to monitor the degenerative index. RESULTS: miR-640 overexpressed in patients derived degenerative nucleus pulposus tissues and cells. The inflammatory environment promoted miR-640 expression via NF-κB signalling pathway. In addition, miR-640 targeted to LRP1 and enhances NF-κB signal activity, which built a positive feedback loop. miR-640 inhibited the expression of ß-catenin and EP300, therefore, restrained WNT signal and induced the degeneration in nucleus pulposus cells. miR-640 inhibitor treatment exhibited the effects of anti-inflammation, reverse WNT signalling pathway exhaustion, and remission of degenerative characteristics in vitro. CONCLUSIONS: miR-640 plays an important role in the degeneration of intervertebral disc and the relative inflammatory microenvironment. It is a promising potential therapeutic target for the low back pain biotherapy.