Search

ABSTRACTWater-free oil production period is an important stage for oil production, prediction and water cut prediction. Because there are many factors affecting the water-free oil production period and the influencing mechanism is complex, it is very difficult to calculate the water-free oil production period. In this paper, the main influencing factors of water-free oil production period are analyzed by the stream tube approach method. The influence law of four influencing factors on water-free oil production period was analyzed and the quantitative relationship between four influencing factors and water-free oil production period were established. The average water saturation of reservoir and water saturation near producers are different which is important for the calculation of theoretical water cut. The quantitative relationship between average water saturation of reservoir and water saturation near producers is established. On this basis, a new method for calculating theoretical water cut is built and is applied to BZ reservoir. The result shows the theoretical water cut calculated by this method is consistent with field data.

ABSTRACTIn this paper, a new method for studying the theoretical water cut increasing rate of water flooding reservoirs is proposed based on the correction of the traditional fractional flow equation. First, the stream tube model was used to solve the saturation distribution field of reverse nine-point injection-production well pattern. Second, through analyzing the saturation results, the linear formula between the average water saturation of the reservoir after water breakthrough and the water saturation at the outlet was established for the first time. Then, based on the linear formula, the traditional fractional flow equation was corrected and a new method was proposed. Finally, the proposed method was applied to Bohai S oilfield to demonstrate its accuracy and practicability. On the one hand, the results show that compared with the traditional fractional flow equation method, the prediction accuracy of the proposed method has increased from 80% to more than 92%. On the other hand, the application of the new method effectively evaluates the development effect of oilfields with high water cut and guides formulation of reasonable adjustment measures.

Interactions of the stripe rust pathogen (Puccinia striiformisf. sp. tritici) with wheat plants activate a wide range of host responses. Among various genes involved in the plant-pathogen interactions, the expressions of particular pathogenesis-related (PR) protein genes determine different defense responses. Different types of resistance have been recognized and utilized for developing wheat cultivars for resistance to stripe rust. All-stage resistance can be detected in seedling stage and remains at high levels throughout the plant growth stages. This type of resistance is race-specific and not durable. In contrast, plants with only high-temperature adult-plant (HTAP) resistance are susceptible in seedling stage, but become resistant when plants grow older and the weather becomes warmer. HTAP resistance controlled by a single gene is partial, but usually non-race specific and durable. The objective of this study was to analyze the expression of PR protein genes involved in different types of wheat resistance to stripe rust. The expression levels of 8 PR protein genes (PR1, PR1.2, PR2, PR3, PR4, PR5, PR9and PR10) were quantitatively evaluated at 0, 1, 2, 7 and 14 days after inoculation in single resistance gene lines of wheat with all-stage resistance genes YrTr1, Yr76, YrSPand YrExp2and lines carrying HTAP resistance genes Yr52, Yr59, Yr62and Yr7B.Races PSTv-4 and PSTv-37 for compatible and incompatible interactions were used in evaluation of PR protein gene expression in wheat lines carrying all-stage resistance genes in the seedling-stage experiment while PSTv-37 was used in the HTAP experiment. Analysis of quantitative real-time polymerase chain reaction (qRT-PCR) revealed that all of the PR protein genes were involved in the different types of resistance controlled by different Yrgenes. However, these genes were upregulated at different time points and at different levels during the infection process among the wheat lines with different Yrgenes for either all-stage resistance or HTAP resistance. Some of the genes were also induced in compatible interactions, but the levels were almost always higher in the incompatible interaction than in the compatible interaction at the same time point for each Yrgene. These results indicate that both allsalicylic acid and jasmonate signaling pathways are involved in both race-specific all-stage resistance and non-race specific HTAP resistance. Although expressing at different stages of infection and at different levels, these PR protein genes work in concert for contribution to different types of resistance controlled by different Yrgenes.

Stripe (yellow) rust, caused by Puccinia striiformis Westend. f. sp. tritici Erikss., is one of the most damaging diseases in wheat and is especially damaging for winter and facultative wheat. The objective of this study was to understand stripe rust resistance in 100 wheat and facultative wheat entries from the International Winter Wheat Improvement Program by conducting experiments in a greenhouse and in four field environments in Washington State, USA, and by genotyping molecular markers linked to Yr genes. Percentages of entries resistant to the rust races at the seedling stage were: PST-17, 44%; PST-37, 32%; PST-43, 45%; PST-45, 49%; PST-116, 18%; PST-100, 17%; and PST-127, 8%. Molecular markers were positive for genes Yr9, Yr17, and Yr18 and negative for Yr5, Yr10, and Yr15. Yr18 was present in 44 entries (44%). By using the highly virulent races PST-127 and PST-100 under controlled conditions, 16 entries were shown to have high-temperature adult-plant (HTAP) resistance and resistant–moderately resistant field reactions at all four field sites. Resistant entries, especially those with HTAP resistance, were also identified in the field experiments.

Stripe rust of wheat, caused by Puccinia striiformis f. sp. tritici, continues to cause severe damage worldwide. Durable resistance is necessary for sustainable control of the disease. High-temperature adult-plant (HTAP) resistance, which expresses when the weather becomes warm and plants grow older, has been demonstrated to be durable. We conducted numerous studies to understand the molecular mechanisms of different types of stripe rust resistance using a transcriptomics approach. Through comparing gene expression patterns with race-specific, all-stage resistance controlled by various genes, we found that a greater diversity of genes is involved in HTAP resistance than in all-stage resistance. The genes involved in HTAP resistance are induced more slowly and their expression induction is less dramatic than genes involved in all-stage resistance. The high diversity of genes and less dramatic induction may explain durability and the incomplete expression level of HTAP resistance. Identification of transcripts may be helpful in identifying resistance controlled by different genes and in selecting better combinations of genes to combine for achieving adequate and durable resistance.

Seventy common spring wheat (Triticum aestivumsubsp. aestivumL.) germplasm lines (Reg. No. GP‐873, PI 660056—Reg. No. GP‐942, PI 660125) that are resistant to stripe rust (caused by Puccinia striiformisf. sp. tritici) were developed from crosses of 66 common and 4 durum [T. turgidumsubsp. durum(Desf.) Husn.] wheat lines originating from 28 countries. Among the new lines, 4 have all‐stage resistance that is effective against the currently predominant races in the United States, 11 have high‐temperature adult‐plant (HTAP) resistance, 13 have effective all‐stage resistance and possibly HTAP resistance, and 42 have HTAP resistance and ineffective all‐stage resistance. Based on their origins and reactions to stripe rust, the majority of the 70 lines may have different genes for stripe rust resistance. These lines were also selected for their relatively good agronomic traits, such as excellent tillering, plump spikes, lodge resistance, proper height, and early maturity and should be useful in diversifying resistance genes used in breeding programs for developing wheat cultivars with stripe rust resistance.

The wheat stripe rust fungus, Puccinia striiformis f. sp. tritici (Pst), does not have a known alternate host for sexual reproduction, which makes it impossible to study gene linkages through classic genetic and molecular mapping approaches. In this study, we compared 4,219 Pst expression sequence tags (ESTs) to the genomic sequence of P. graminis f. sp. tritici (Pgt), the wheat stem rust fungus, using BLAST searches. The percentages of homologous genes varied greatly among different Pst libraries with 54.51%, 51.21%, and 13.61% for the urediniospore, germinated urediniospore, and haustorial libraries, respectively, with an average of 33.92%. The 1,432 Pst genes with significant homology with Pgt sequences were grouped into physical groups corresponding to 237 Pgt supercontigs. The physical relationship was demonstrated by 12 pairs (57%), out of 21 selected Pst gene pairs, through PCR screening of a Pst BAC library. The results indicate that the Pgt genome sequence is useful in constructing Pst physical maps.