Optimization of Injection Parameters for Profile Control and Flooding in an Oilfield during High Water Cut Period

In order to improve the effect of water control and oil stabilization during high water cut period, a mathematical model of five point method well group was established with the high water cut well group of an Oilfield as the target area, the variation law of water cut and recovery factor of different injection parameters was analyzed, and the optimization research of injection parameters of polymer enhanced foam flooding was carried out. The results show that the higher the injection rate, the lower the water content curve, and the higher the oil recovery rate. As the foam defoamed when encountering oil, when the injection time was earlier than 80% of water cut, the later the injection time was, the better the oil displacement effect would be. When the injection time was later than 80% of water cut, the later the injection time was, the worse the oil displacement effect would be. The larger the injection volume, the lower the water content curve and the higher the recovery rate. After the injection volume exceeded 0.2 PV, the amplitude of changes in water content and recovery rate slowed down. The optimal injection parameters of profile control agent for high water content well group in Oilfield A were: injection rate of 15 m3/d, injection timing of 80% water content, and injection volume of 0.2 PV.

Study and Application of Horizontal Well Productivity Formula with Continuous Time-Varying Considered

The horizontal well technology has been widely applied to enhanced oil recovery for low permeability and heavy oil reservoir. It is the important basis for designing and optimizing horizontal well to determine the productivity. The productivity determination of horizontal wells in offshore oil fields is mainly based on the actual productivity data of producing directional wells in the similar reservoirs nearby. Considering pressure drop and oil layer thickness to calculate the productivity, this method lacks certain theoretical basis and requires rich working experience for reservoir engineers. The other method is Joshi Formula which needs the known horizontal well control radius to be known. But the control radius is man-made at certain degree. In order to address the shortcomings of existing methods, a new reservoir engineering method was proposed to determine the horizontal well productivity formula, horizontal flow pattern and control radius based on the principle of equivalent flow resistance and conformal transformation. This method has overcome the disadvantage of determining on person. It provided some theoretical basis for getting the horizontal well productivity and is of some guiding meaning for evaluating the productivity of adjustment wells and development wells.

The Research and Applications of Remaining Oil Potential Tapping in High Watered Stage for Heavy Oil Reservoir in Bohai

S oil field is a typical of water injection development of heavy oil reservoir in Bohai, and the formation of crude oil viscosity is 42 - 284 mPa?s. Due to the formation of crude oil viscosity, the oil field development gradually faces a series of problems as rapid rise of water cut, rapid decline of output, high water cut of oil wells and others. In order to improve the effect of oilfield development, it is necessary to increase the output of the oilfield by adjusting wells for the potential in the oilfield. However, due to the high cost of drilling, operation and testing of offshore oilfields, offshore oilfields require more elaborate description of residual oil and adjustment wells. With the continuous downturn in international oil prices and the lack of new testing data in old oilfields, it is urgent to re-use the existing data in oilfields through innovative methods to achieve a detailed description of the remaining oil in the oilfields and improve the precision research of indexing wells and ensure the reliable implementation of adjustment wells. Based on the existing dynamic data of S oilfield, this paper proposes a new method to quantitatively evaluate water flooding coefficient by using tracer theory to establish tracer data, and quantitatively evaluates the vicinity of the fault by means of image reflection and potential superposition and find the residual oil in the imperfect area of the well network, combined with the numerical simulation method to realize the fine description of remaining oil and improve the research precision of the adjustment well. Through the research in this paper, S oilfield has proposed to location of six adjustment wells which has implemented two. The production confirmed that the method of this paper has some reliability, while the method of heavy oil in the high water cut stage of residual oil fine description. The research of enhanced oil recovery in the stage has certain guiding significance for heavy oil reservoirs.

Study on Water Injection Formula by Grey Correlation Method for Offshore Water Flooding Reservoir

Based on the development of the offshore water drive reservoir, the determination of reasonable water injection of monolayer and single well affects the distribution of remaining oil and development effect of oil field water flooding, so this paper, using the grey correlation analysis method, studies the main factors influencing the dividing coefficient of water-injection and weight. This method takes into account the effective thickness, permeability, injection-production well spacing, the number of injection-production wells, and the direction of formation coefficient factors such as the influence of the dividing coefficient for injection. The formula for water-injection multi-factor controlled is established, at the same time, applying water injection formula of this article and the conventional on injection allocation of A-platform offshore injection wells. And the difference of single-well injection-allocation quantity in layers is analyzed. Based on a platform offshore, layers exist in the process of water flooding and the problems such as the contradiction between the layers, put forward the necessity of layered water injection through this article to determine water injection formula and injection allocation on a platform of injection wells by implementing effect which can be found. A platform for water flooding development of water cut under control, natural decline rate reduced to verify the reliability and practicability of the formula to determine injection in this paper. It has certain guiding significance to the offshore for the water-injection development oilfield.

Research and Practice on the Profile Control Characteristics of Emulsions in Bohai Oil Field

In order to study the profile control characteristics of emulsions in porous medium, the heterogeneous experimental model was established, by which the experimental scheme was designed with different permeabilities, matching degree of particle size and concentration of emulsions. Based on experimental results of physical simulation, the concept of distributing rate and changing coefficient was introduced to quantitatively evaluate the profile control characteristics of emulsions. The results of the study show that, as the permeability ratio and emulsion concentration increase, the profile control characteristics of emulsions will enhance. The profile control characteristics of emulsions will be the best. The profile control scheme with emulsions was implemented in Bohai X oil field, The research results can be used for reference to design the profile control scheme in Bohai heterogeneous reservoir.

Classification Study on Relative Permeability Curves

The classification method of relative permeability curves is rarely reported, when relative permeability curves are applied;if the multiple relative permeability curves are normalized directly, but not classified, the calculated result maybe cause a large error. For example, the relationship curve between oil displacement efficiency and water cut, which derived from the relative permeability curve in LD oilfield is uncertain in the shape of low water cut stage. If being directly normalized, the result of the interpretation of the water flooded zone is very high. In this study, two problems were solved: 1) The mathematical equation of the relationship between oil displacement efficiency and water cut was deduced, and repaired the lost data of oil displacement efficiency and water cut curve, which solve the problem of uncertain curve shape. After analysis, the reason why the curve is not available is that relative permeability curves are not classified and optimized;2) Two kinds of classification and evaluation methods of relative permeability curve were put forward, the direct evaluation method and the analogy method;it can get the typical relative permeability curve by identifying abnormal curve.

An Effective Thin Reservoir Identification Method for Fine Oilfield Development

Thin reservoirs prediction method such as spectral inversion has drawn considerable attention in recent years. In order to avoid extracting wavelets within the whole field area purposeless and to make the filtered data has preferable fidelity as well as signal-to-noise ratio, an effective structural constrained thin reservoir description method which combines spectral inversion and wide-band Ricker wavelet filtering technology has been proposed in this paper. The method given here is more credible and is suitable for the prediction of middle-deep thin reservoirs. We take LD-A structure within Bohai Bay Basin as an example to show the implement of our method. Several sets of thin sand layers which are hardly to recognize originally have been finally identified. Also, with the application of this method, a high-production thin reservoir of LD-B structure has been identified accurately, which provides credible information for subsequent fine oil exploration and development.

Research on Optimization Design of Deep Profile Control Injection Scheme in Block S

In view of the rapid decline rate of oil production and gradual increase of water cut in oil wells in Block S, based on the determination of the formula of foam profile control agent, the optimization study of foam profile control injection scheme was carried out. Petrel software is used to establish a facies controlled geological model based on stochastic modeling method in Block S, and CMG software is used for numerical simulation to design 7 sets of foam profile control prediction schemes. Dynamic data and numerical simulation methods are used to optimize foam injection mode and injection cycle. By simulating and calculating, the optimal injection method of alternating gas and liquid injection and the optimal plan with an injection period of 2 months were selected. Through the calculation results of various research plans, it can be seen that the water content of the optimal plan has decreased significantly, and the oil production rate has increased significantly, in order to slow down production decline, control water content rise, extend the economic recovery period of the oilfield, and achieve the goal of improving oil recovery.

Diffuse Intrinsic Pontine Gliomas Exhibit Cell Biological and Molecular Signatures of Fetal Hindbrain-Derived Neural Progenitor Cells

Diffuse intrinsic pontine glioma(DIPG) is the main cause of brain tumor-related death among children.Until now, there is still a lack of effective therapy with prolonged overall survival for this disease. A typical strategy for preclinical cancer research is to find out the molecular differences between tumor tissue and para-tumor normal tissue, in order to identify potential therapeutic targets. Unfortunately, it is impossible to obtain normal tissue for DIPG because of the vital functions of the pons.Here we report the human fetal hindbrain-derived neural progenitor cells(pontine progenitor cells, PPCs) as normal control cells for DIPG. The PPCs not only harbored similar cell biological and molecular signatures as DIPG glioma stem cells, but also had the potential to be immortalized by the DIPG-specific mutation H3 K27 M in vitro. These findings provide researchers with a candidate normal control and a potential medicine carrier for preclinical research on DIPG.

Scalable and general synthesis of spinel manganese- based cathodes with hierarchical yolk-shell structure and superior lithium storage properties

Hierarchical yolk-shell structured cathodes with controllable composition are potentially attractive materials for the fabrication of lithium-ion batteries, but they are difficult to synthesize. In this work, we present a simple, scalable, and general morphology-inheritance strategy to synthesize spinel manganese cathodes with a hierarchical yolk-shell structure. Starting from uniform Mn carbonate spheres prepared by an ultrafast and scalable microwave-assisted method, we show that the subsequent sintering results in the formation of Mn203 precursors with a yolk-shell structure, which can be effectively transferred to spinel manganese cathodes via simple impregnation and solid-state reaction. Owing to the simple and scalable nature of the present strategy, materials prepared through this approach have great potential as cathodes of lithium-ion batteries, where they can lead to high specific capacity, outstanding cyclability, and superior rate capability. In particular, both LiMn204 and LiNi05Mn1504 with hierarchical yolk-shell structure achieved nearly theoretical capacity, without any apparent decay after 100 cycles at I C. Moreover, 80% of the initial discharge capacities of both samples can be maintained for up to 500 cycles at a high rate of 10 C.

Somatic GJA4 mutation in intracranial extra-axial cavernous hemangiomas

Objective Extra-axial cavernous hemangiomas(ECHs)are sporadic and rare intracranial occupational lesions that usually occur within the cavernous sinus.The aetiology of ECHs remains unknown.Methods Whole-exome sequencing was performed on ECH lesions from 12 patients(discovery cohort)and droplet digital polymerase-chain reaction(ddPCR)was used to confirm the identified mutation in 46 additional cases(validation cohort).Laser capture microdissection(LCM)was carried out to capture and characterise subgroups of tissue cells.Mechanistic and functional investigations were carried out in human umbilical vein endothelial cells and a newly established mouse model.Results We detected somatic GJA4 mutation(c.121G>T,p.G41C)in 5/12 patients with ECH in the discovery cohort and confirmed the finding in the validation cohort(16/46).LCM followed by ddPCR revealed that the mutation was enriched in lesional endothelium.In vitro experiments in endothelial cells demonstrated that the GJA4 mutation activated SGK-1 signalling that in turn upregulated key genes involved in cell hyperproliferation and the loss of arterial specification.Compared with wild-type littermates,mice overexpressing the GJA4 mutation developed ECH-like pathological morphological characteristics(dilated venous lumen and elevated vascular density)in the retinal superficial vascular plexus at the postnatal 3 weeks,which were reversed by an SGK1 inhibitor,EMD638683.Conclusions We identified a somatic GJA4 mutation that presents in over one-third of ECH lesions and proposed that ECHs are vascular malformations due to GJA4-induced activation of the SGK1 signalling pathway in brain endothelial cells.

Common Postzygotic Mutational Signatures in Healthy Adult Tissues Related to Embryonic Hypoxia

Postzygotic mutations are acquired in normal tissues throughout an individual’s lifetime and hold clues for identifying mutagenic factors.Here,we investigated postzygotic mutation spectra of healthy individuals using optimized ultra-deep exome sequencing of the time-series samples from the same volunteer as well as the samples from different individuals.In blood,sperm,and muscle cells,we resolved three common types of mutational signatures.Signatures A and B represent clocklike mutational processes,and the polymorphisms of epigenetic regulation genes influence the proportion of signature B in mutation profiles.Notably,signature C,characterized by C>T transitions at GpCpN sites,tends to be a feature of diverse normal tissues.Mutations of this type are likely to occur early during embryonic development,supported by their relatively high allelic frequencies,presence in multiple tissues,and decrease in occurrence with age.Almost none of the public datasets for tumors feature this signature,except for 19.6%of samples of clear cell renal cell carcinoma with increased activation of the hypoxia-inducible factor 1(HIF-1)signaling pathway.Moreover,the accumulation of signature C in the mutation profile was accelerated in a human embryonic stem cell line with drug-induced activation of HIF-1α.Thus,embryonic hypoxia may explain this novel signature across multiple normal tissues.Our study suggests that hypoxic condition in an early stage of embryonic development is a crucial factor inducing C>T transitions at GpCpN sites;and individuals’genetic background may also influence their postzygotic mutation profiles.

ADAR1 regulates vascular remodeling in hypoxic pulmonary hypertension through N1-methyladenosine modification of circCDK17

Pulmonary hypertension(PH)is an extremely malignant pulmonary vascular disease of unknown etiology.ADAR1 is an RNA editing enzyme that converts adenosine in RNA to inosine,thereby affecting RNA expression.However,the role of ADAR1 in PH development remains unclear.In the present study,we investigated the biological role and molecular mechanism of ADAR1 in PH pulmonary vascular remodeling.Overexpression of ADAR1 aggravated PH progression and promoted the proliferation of pulmonary artery smooth muscle cells(PASMCs).Conversely,inhibition of ADAR1 produced opposite effects.High-throughput whole transcriptome sequencing showed that ADAR1 was an important regulator of circRNAs in PH.CircCDK17 level was significantly lowered in the serum of PH patients.The effects of ADAR1 on cell cycle progression and proliferation were mediated by circCDK17.ADAR1 affects the stability of circCDK17 by mediating A-to-I modification at the A5 and A293 sites of circCDK17 to prevent it from mlA modification.We demonstrate for the first time that ADAR1 contributes to the PH development,at least partially,through m1A modification of circCDK17 and the subsequent PASMCs proliferation.Our study provides a novel therapeutic strategy for treatment of PH and the evidence for circCDK17 as a potential novel marker for the diagnosis of this disease.

Human brain arteriovenous malformation:an analysis of differential expressed genes

Background:Much still remains unknown about the pathogenesis of brain arteriovenous malformations (AVMs).Previous studies have revealed the abnormal expression of various angiogenesis-related genes in AVMs.To further understand this disease,we sought to identify genes differently expressed in AVMs by means of the gene microarray technique.Methods:Nine AVMs specimen and nine samples of normal vessels are collected.Total RNA isolated from these specimen is hybridized with Oligonucleotide array and gene analysis was conducted.Analyzing data with the help of significance analysis of microarrays (SAM) and a free web-based molecular annotation system 3.0 (MAS 3.0).Results:The SAM method identify 37 gene significantly up-regulated and 10 genes down-regulated in AVMs.Conclusions:Among those genes,VACN,SPARK and ARHGAP18 seem to play a facilitating role during the genesis of AVMs.Multiple pathways,as MAPK pathway,may also be involved.