Short Effective Period Research Articles

A strong stability gel foam for water shutoff during oil and gas reservoir development

In view of the short effective period of conventional foam for water shutoff during oil and gas reservoir development, a strong stability gel foam system is proposed in this work. By comparing the foam properties of different foaming systems, the optimized formulation of foam system is “0.3% SDS (sodium dodecyl sulfate) + 0.4% HPAM (partially hydrolyzed polyacrylamide) + 0.3% SD-107 (organic chromium).” At 50 °C and 10 000 mg/l salinities, the volume of foam is basically unchanged after a short time of defoaming and finally remains above 70%, and the drainage half-life can reach 16 days. The polymer and crosslinker form a stable three-dimensional network structure on the Plateau boundary after foaming, which has good viscosity and viscoelasticity. The foam system has excellent temperature and salt resistance. It is appropriate for medium and low temperature shallow reservoirs. The foam system has a good plugging efficiency. It can effectively plug the fracture and improve the sweep volume, which has a good application prospect.

Application of separate layer water injection in high differential pressure wells

With the development of a heavy fine-RRB-layering system and dynamic adjustment, the number of large differential pressure wells increases gradually. The effect of high-pressure difference wells on water injection development is that it is difficult to separate water injection allocation, low pass rate of layers and short effective period of separate sealing, which affects the development effect of water flooding. For this reason, the research on stratified water injection technology with large pressure differences is carried out using step-by-step throttling. The throttling pressure difference borne by the water nozzle is reduced. The large throttling pressure difference produced by the water nozzle is realized. The qualified rate of the layer section is increased to improve the anti-creep performance of the expansion Packer and the sealing effect of large pressure difference injection wells and to extend the service life of the Packer. The field application results of 216 wells in the Shengli Oil Field show that the technique can effectively improve the pass rate of the layers and the sealing effect of the layers and prolong the life of the string.

Development and Application of Well-Test Model after Injection Biological Nanomaterials

Nanomaterials are gradually shining in the petroleum industry and have made great achievements in EOR, pipeline coating, fracturing, and other aspects. In practical application, they have the advantages of long validity period and more environmental friendliness. At the same time, due to the short effective period of conventional plugging removal measures such as acidizing and fracturing, which are not friendly to the environment, nanomaterials are gradually applied to reduce pressure and increase injection of injection wells, and good application results are obtained. In this study, a new biological nanomaterial with long-term injection enhancement characteristics was evaluated. To have a better understanding of the reservoir performance of water injection wells after pressure reduction and injection increase measures, it is necessary to establish the well test model after the step-down and injection increase measures of biological nanomaterials that are taken for water injection wells. In this paper, the influence of the injection amount of bionanomaterials on the permeability is studied, and the rule of the permeability around the injection well with the distance from the bottom of the well is analyzed. On this basis, the flow mathematical model of three zones (inner zone, transition zone, and outer zone) of bionanosolution is established. Then, using the basic principles of fluid mechanics and the Laplace transform principle, a mathematical model of the bottom hole pressure response of water injection wells in the third zone of the bionanosolution reservoir is obtained, and the influence of the key process parameters of the bionanosolution water injection on the bottom hole pressure is analyzed. The established well test interpretation model can be used to calculate the near wellbore permeability, reservoir skin factor, reservoir sweep radius, and reservoir resistance coefficient. Based on application examples, it was determined that the fitting results of the interpretation chart are in good agreement with the field test data, and the reservoir parameters obtained from the interpretation are reasonable and reliable. The findings of this study can help for better understanding of the dynamic change law of reservoir after injection of biological nanomaterials or similar plugging removal measures (the improvement effect varies with the distance from the bottom hole). To the best of our knowledge, it is the first paper on the application of biological nanomaterials in reducing pressure and increasing injection in injection wells.

Abdominal sepsis

Background. Sepsis is a life-threatening acute organ dysfunction that occurs as a result of dysregulation of the macroorganism’s response to infection. Septic shock is a variant of sepsis characterized by the circulatory failure, manifested by hypotension and increased lactate levels >2 mmol/L despite adequate infusion, which requires the administration of vasopressors to maintain average blood pressure >65 mm Hg.
 Objective. To describe the management of patients with abdominal sepsis.
 Materials and methods. Analysis of literature data on this topic.
 Results and discussion. Complicated intra-abdominal infection (IAI) is the growth of pathogenic microorganisms in a usually sterile abdominal cavity, usually due to the perforation of the hollow organs. Uncomplicated IAI involves transmural inflammation of the digestive tract, which does not spread beyond the hollow organ. If uncomplicated IAI are not treated, there is a possibility that they will progress to complicated ones. Measures to control the source of infection include the drainage of abscesses or places of accumulation of infected fluid, removal of necrotic infected tissues and restoration of the anatomy and functions of the affected area. Several multivariate studies have found that failure to adequately control the source of infection is a risk factor for adverse outcomes and death in patients with IAI. Surviving sepsis and other recommendations also support the need for early control of the source of infection. In a study by B. Tellor et al. (2012) mortality was 9.5 % among individuals with adequate control of the infection source and 33.3 % among patients who failed to achieve such control. In some situations, it is advisable to manage patients conservatively. Thus, in appendicular infiltration, most studies have demonstrated the benefits of conservative management (Andersson R.E., Petzold M.G., 2007). Management of IAI without final control of the primary source is possible in cases where the organism has already overcome the infection, and surgery can only increase the number of complications. In general, patients with localized infections may need less invasive management. Thus, percutaneous drainage can be used for localized accumulations of fluid in the abdominal cavity. 80-92 % of drainage procedures are successful on the first attempt. <5 % of patients require surgical treatment. Such drainage procedures are used in infected pancreatic necrosis, and the final debridement of the infection source may be delayed. In critically ill patients, damage control laparotomy and limited intervention (resection without reanastomosis or stoma formation, temporary drainage and tamponade of the abdominal cavity if necessary, temporary closure of the abdominal cavity) are performed to control the infection. Indications for damage control laparotomy include inability to achieve adequate control of the source of IAI during primary laparotomy, hemodynamic instability, the need to re-evaluate the condition of the problematic anastomosis, and diffuse peritonitis. A prospective study of staged laparotomies revealed a shorter length of stay in the intensive care unit, a lower incidence of complications and lower treatment costs using this method compared to the standard one. Antibacterial support of surgical interventions is an important aspect of treatment. In conditions of increasing antibiotic resistance, antibiotics should be prescribed strictly in accordance with the recommendations and for as short effective period as possible.
 Conclusions. 1. Despite the fact that approaches are changing, control of the IAI source remains the main method of treatment of most patients with IAI. 2. The choice of empirical antibacterial therapy should be based on the risk assessment and potential of resistant bacteria. 3. The duration of antimicrobial therapy can be significantly reduced (4 days).

Application of highly deviated well injection technology in Huabei Oilfield

With the deepening of oilfield development, the amount of highly deviated (≥30°) layered water injection wells have increased year by year. In order to solve the technical bottlenecks such as poor sealing of the columns and short effective period of dispensing. The self-supporting step-by-step releasable packers with the outer diameter of 114mm and the highly deviated well ball seat are developed. The packer integrates the function of centering-righting, ball centering, spiral righting and stepping unblocking and the ball seat has self-locking function and able to meet the requirements of pipe string used in highly deviated wells within 60°. Through the field application, a highly deviated well-dispensing process technology suitable for the characteristics of Huabei Oilfield has been formed, it has a strong popularization and application value.

Pollen Tube Growth and Embryo Sac Development in ‘Pozna Plava’ Plum Cultivar Related to Fruit Set

A newly released, late ripening plum cultivar ‘Pozna Plava’ sets fruit poorly, although it produces high quality fruit. This study aimed to evaluate which factors in the reproductive process could be related to the lack of fruit set. In two consecutive years, establishment of a suitable polleniser and the stage of ovule development at anthesis as well as initial and final fruit set have been studied. In addition to this, the impact made by temperature fluctuations on the interaction between male gametophytes and female sporophytes was also analysed. Growth of the pollen tubes in the style and penetration into the nucellus as well as fruit set were more effective in cross-pollination than in open and self-pollination. A relative delay in ovule development was observed, and most ovules had an embryo sac with eight nuclei. Considering the results of the quantitative parameter study of pollen tube growth in the ovary as well as the results of the stage of ovule development, a conclusion can be made that this cultivar is characterised by an extremely short effective period of pollination.