Daqing Oil Field Research Articles

Effect of the kappa angle on depth of focus after implantation of the TECNIS Symfony intraocular lens.

To evaluate the clinical effect of TECNIS Symfony intraocular lens (IOL) implantation and identify the effect of kappa angle on the depth of focus (DOF) after implantation. This prospective clinical study included consecutive patients who underwent cataract surgery and TECNIS Symfony IOL implantation at the Daqing Oilfield General Hospital from January 2019 to September 2019. Patients were divided into three groups according to the preoperative kappa angle (r): A (0 < r ≤ 0.2), B (0.2 < r ≤ 0.4), and C (r > 0.4). Uncorrected visual acuity was performed preoperatively and at 7days, 1month, and 3months postoperatively. Synthetical optometry, higher-order aberrations, and defocus examinations were performed at 3months postoperatively. Single-factor analysis of variance and Spearman correlation coefficient were used for data analysis. The uncorrected visual acuity values of the three groups were significantly improved postoperatively, compared with preoperative values (p < 0.001). Three months postoperatively, the best-corrected visual acuity values of the three groups were 0.11±0.02 logarithm of the minimum angle of resolution (logMAR), 0.09±0.03 logMAR, and 0.11±0.03 logMAR, respectively. Spherical equivalent (SE) values were 0.37±0.08 D, 0.41±0.06 D, and 0.42±0.06 D, respectively. Best-corrected visual acuity and SE did not significantly differ among the three groups (F = 1.254, p = 0.135; F = 0.849, p = 0.228). There was no significant difference in SE between the three groups (F = 1.658, p = 0.312). Moreover, higher-order aberrations did not significantly differ among the three groups (p > 0.05). The kappa angle was negatively correlated with the postoperative DOF (r = -4.341, p = 0.026). Three months postoperatively, 54.55% of patients exhibited DOF ≥ 3 D, while 92.42% of patients exhibited DOF ≥ 2 D. The ranges of DOF in the three groups were 3.18±0.27 D, 2.83±0.80 D, and 2.57±0.89 D, respectively; the difference among the three groups was statistically significant (F = 5.689, p = 0.037). Most patients achieved full-range vision after TECNIS Symfony IOL implantation, but the DOF narrowed for those with an excessively large kappa angle, which indicates a need for careful selection.

Chemotaxis Toward Crude Oil by an Oil-Degrading Pseudomonas aeruginosa 6-1B Strain.

The chemotactic properties of an oil-degrading Pseudomonas aeruginosa strain 6-1B, isolated from Daqing Oilfield, China, have been investigated. The strain 6-1B could grow well in crude oil with a specific rhamnolipid biosurfactant production. Furthermore, it exhibits chemotaxis toward various substrates, including glycine, glycerol, glucose, and sucrose. Compared with another oil-degrading strain, T7-2, the strain 6-1B presented a better chemotactic response towards crude oil and its vital component, n-alkenes. Based on the observed distribution of the strain 6-1B cells around the oil droplet in the chemotactic assays, the potential chemotaxis process of bacteria toward crude oil could be summarized in the following steps: searching, moving and consuming.

Using machine learning to predict post-operative depth of focus after cataract surgery with implantation of Tecnis Symfony

To predict post-operative depth of focus (DoF) using machine learning techniques after cataract surgery with Tecnis Symfony implantation and determine associated impact factors. This was a retrospective cohort study among patients receiving Tecnis Symfony implantation, an extended-range-of-vision intraocular lens, during October 2016-January 2020 at Daqing Oilfield General Hospital, China. Four different predictive models were used to predict good post-operative DoF (⩾2.5 D): Extreme Gradient Boost (XGBoost), random forest (RF), LASSO penalized regression, and multivariable logistic regression (MLR). Apriori algorithm was employed to further explore the association between patient attributes and DoF. A total of 182 unique cases (143 patients) were included. The XGBoost model produced the best predictive accuracy compared to RF, LASSO, and MLR models. Overall performance of the best fitting XGBoost model was as follows: accuracy = 70.3%, AUC = 80.2%, sensitivity = 65.5%, and specificity = 87.5%. The Apriori algorithm identified six preoparative attributes with substantial effects on good post-operative DoF: low anterior chamber depth (ACD) (1.9 to <2.5 mm), smaller pupil size (1.7 to <2.5 mm), low-to-mid axial length (21 to <23 mm), minimum astigmatism degree (-0.2 to 0 diopter), low IOP (9 to <12 mmHg), and medium lens target refractive error (-0.5 to <-0.25 diopter). Machine Learning models were able to predict good post-operative DoF among cataract patients receiving a Tecnis Symfony ocular lens implantation. The accuracy of the model was above 70%. The Apriori algorithm identified six preoperative attributes with a strong association with post-operative DoF.

Enhanced oil recovery mechanisms of polymer flooding in a heterogeneous oil reservoir

Abstract Taking reservoir rocks and fluids of the Daqing, Dagang and Changqing oilfields as research objects, the EOR mechanisms and technical approach of polymer flooding were discussed. By comparing the displacement performances of ordinary polymer, glycerol, polymer in “sheet-net” structure and heterogeneous weak gel at the same viscosity and concentration, the relationship between the viscosity of polymer displacement agents and displacement performance was demonstrated, and the method of improving polymer flooding effect was worked out. The main mechanism of polymer flooding to increase oil recovery is the swept volume expansion of water injection due to polymer retention in porous media. The viscosity of polymer agents has no positive correlation with polymer flooding effect. Although polymer of “sheet-net” structure has strong capacity in increasing viscosity, it has poor compatibility with pore throat structure of reservoir rock, low injectivity and low shear resistance. Heterogeneous weak gel system has higher adsorption and capture capacity in porous media, which is easy to retain in porous media, and can effectively establish seepage resistance in high permeability layers (zones). Compared with polymer solutions with the same viscosity or concentration, it has stronger ability to expand swept volume. Long term injection of polymer flooding agents will inevitably lead to fluid entry profile reversal, and thus worsening of polymer flooding effect. Alternate injection of high retention and low or non-retention displacement agents can further improve the displacement effect of polymer flooding agents.

Well log data super-resolution based on locally linear embedding

Unconventional remaining oil and gas resources such as tight oil, shale oil, and coalbed gas are currently the focus of the exploration and development of major oil fields all over the world. Therefore, to make best understand of target reservoirs, enhancing the vertical resolution of well log data is crucial important. However, in the face of the continuous low-level fluctuations of international oil price, large scale use of expensive high resolution well logging hardware tools has always been unaffordable and unacceptable. In another aspect, traditional well log interpolation methods can always not realize high reliable information enhancement for crucial high frequency components. In this paper, in order to improve the well log data super-resolution performance, we propose for the first time to employ Locally Linear Embedding (LLE) technique to reveal the nonlinear mapping relationship between 2-times-scale-difference well log data. Several super resolution experiments with well log data from a given area of Daqing Oil field, China, were conducted. Experimental results illustrated that the proposed LLE-based method can efficiently achieve more reliable super-resolution results than other state-of-the-art methods.

A comparative analysis and rapid performance prediction of polymer flooding process by coupling reservoir simulation with neural networks

Accelerated technological progresses offer massive amounts of data, prompting decision making for any asset to be more complicated and challenging than before. Data-driven modelling has gained popularity among petroleum engineering professionals by turning big data into valuable insights that introduces fast and reliable decision making. In this study, a viscosifying polymer flooding performance-forecasting tool is developed using an artificial neural network-based data-driven model. A wide variety of reservoir and operational scenarios are generated to inclusively cover possible conditions of the process. Each scenario goes through no injection, water-only flooding, polymer followed by waterflooding and polymer-only flooding schemes. Neural network models were trained with three representative performance indicators derived from simulator outputs; efficiency, water-cut and recovery factor. Practicality of the tool in assessing probabilistic and deterministic predictions is demonstrated with a real polymer-flooding case of Daqing Oil Field. [Received: April 15, 2020; Accepted: June 26, 2020]

Recent Advances in Polymer Flooding in China: Lessons Learned and Continuing Development

SummaryPolymer flooding is one of the most promising chemical enhanced-oil-recovery (EOR) techniques. It offers a high incremental-oil-recovery factor (IORF), low cost, and wide reservoir applicability. The first large commercial polymer-flooding application began in Daqing Oil Field and remains the largest polymer application in the world. However, encouraged by the success of previous field applications and new findings regarding the viscoelasticity of polymers in the reduction of residual oil saturation (ROS), high-concentration high-molecular-weight (MW) polymer-flooding (HCHMW) field tests have been conducted in many oil fields in China. Although some of these field tests in Daqing are well-documented, subsequent progress has seldom been reported. Moreover, recent references about the latest polymer-flooding applications in China reveal that HCHMW has only a limited application in Daqing. This is not in agreement with previous reports and expectations, especially given that viscoelasticity has been drawing increased attention. This paper explains why HCHMW is not currently widely used. New types of amphiphilic polymers are also field tested in China. Lessons learned from polymer-flooding practices in offshore reservoirs, heavy-oil reservoirs, and conglomerate reservoirs are given to help reduce risks and costs of polymer flooding in the low-oil-price era. EOR techniques in post-polymer-flooding reservoir field tests are also compared. In addition to providing useful information for engineers, this paper helps clarify some misconceptions—such as injecting the most viscous polymer possible—in polymer-flooding implementations, according to polymer-flooding practice in China. Annual oil production using polymer flooding as well as polymer utility factors (UFs) are given. Various technical parameters, such as polymer slug, viscosity, IORF, oil-increase factor (OIF), and water-cut decrease, are provided to better understand polymer-flooding evaluation as well economics.

Analysis of the channeling of water injection in low permeability reservoirs with interlayer considering the seepage–stress coupling

PurposeThis paper aims to establish a mathematical model for water-flooding considering the impact of fluid–solid coupling to describe the process of development for a low-permeability reservoir. The numerical simulation method was used to analyze the process of injected water channeling into the interlayer.Design/methodology/approachSome typical cores including the sandstone and the mudstone were selected to test the permeability and the stress sensitivity, and some curves of the permeability varying with the stress for the cores were obtained to demonstrate the sensitivity of the formation. Based on the experimental results and the software Eclipse and Abaqus, the main injection parameters to reduce the amount of the injected water in flowing into the interlayer were simulated.FindingsThe results indicate that the permeability of the mudstone is more sensitive to the stress than sandstone. The injection rate can be as high as possible on the condition that no crack is activated or a new fracture is created in the development. For the B82 block of Daqing oilfield, the suggested pressure of the production pressure should be around 1–3MPa, this pressure must be gradually reached to get a higher efficiency of water injection and avoid damaging the casing.Originality/valueThis work is beneficial to ensure stable production and provide technical support to the production of low permeability reservoirs containing an interlayer.

A Study on rational well spacing for Producing Evaluation and Solution Scheme of the Water Injection in Northern Daqing Blocks

The inter of daqing oil field has already entered the period of high water cut,with the deepening of oil and gas field development technology,the current water flooding development objects in the high and moderate permeableness layers gradually transformed into poor thin layers, such reservoirs with the complicated structure have poor development benefits, but the remaining reserves of several million tons of the demonstrated reserves mainly exist in low permeability poor thin layers. The development well pattern deployment of thin and poor pay zones still have the problems of the imperfectly injection-prodction relation, poor water flooding wells driving, and low producing degree,and it is still difficult to employ the reservoirs with poor development. In order to improve the effect of oil development,and enhance the producing degree of low poor thin reservoirs with permeability,so that it can establish the effective driving energy system,the research on effective producing limitation and technology policy limitation of thin and poor pay zones need to strengthen. Through a lot of research abroad effective producing and rational development technology policy limitation research results on the thin and poor pay zones, based on the basis of previous word, the paper study the microscopic pore structure of thin and poor layers, and compares with the thick reservoirs, while carrying out the research on effective producing limitation and development technology policy limitation of thin and poor layers. On the basis of the standard model fitting the paper analyzed the plane and vertical distribution characteristics of the remaining and also discussed the rational well spacing for producing evaluation.

Sand Production Prediction Model for Tight Sandstone Oil Reservoirs

Tight oil is an important unconventional resource, and sand production is an inevitable challenge during the field development. In this paper, based on data from the Daqing oilfield in Songliao Basin, the sand production of the tight sandstone oil reservoir is studied from the perspective of seepage and in situ stress distribution. Based on the combination of the formation fluid seepage law and the stress distribution around the well, a sand production prediction model is proposed to quantitatively estimate the sand production rate. The sand production prediction model is built based on the derivation of the sand production rate, which is well validated against the field data in the Daqing field with a relative error of 4.38%.The following conclusions are drawn: (1) after the critical pressure difference is exceeded, the sand production rate is smaller with a higher flowing bottom-hole pressure; (2) a smaller sand production radius makes the formation more unstable and causes a more severe sand production; and (3) various sand production rates exhibit due to different permeabilities. A larger permeability results in a higher sand production rate. The findings of this study can help for sand production prediction in the tight sandstone oil reservoir.

Faults Delicate Description Technology by Well-to-seismic Integration is applied to the Sabei Development Area of Daqing oil field

Due to the effect of faults, there are some problems such as the high oil wells ratios, and the partial incomplete injection-production relationship which effect the yield of the development in the west of Sabei Development Area that has a high content of oil. The effective method to improve the water-flooding control degree in densely faulted area is to further study the developmental morphology of fault area and improve the injection-production relationship. This passage combines the advantages of interpretation seismic data with high resolution and vertical plane strong data continuity, forming a technology of the description of well seismic combined with fault by breakpoint data logging boot, seismic trace, identify the properties of body, and carry out the verification of the interpretation results of well seismic combined with fault by dynamic analysis methods, implement the fault’s shape in the top surface of each reservoir group of the study area, and applied the guidance of research to guide the adjustment of injection-production system in the West of oil area, improve the injection-production relationship of complex fault zone, achieving a good effect of tapping the potential.

Discovery of Late Jurassic Sporopollen Assemblage from the Tamulangou Formation in the Hongqi Sag of the Hailar Basin, Inner Mongolia, China

Acta Geologica Sinica - English EditionVolume 94, Issue 5 p. 1718-1720 Research Advance Discovery of Late Jurassic Sporopollen Assemblage from the Tamulangou Formation in the Hongqi Sag of the Hailar Basin, Inner Mongolia, China Chuanbiao WAN, Exploration and Development Research Institute of Daqing Oilfield Company Ltd., Daqing, Heilongjiang, 163712 ChinaSearch for more papers by this authorYunfei XUE, Exploration and Development Research Institute of Daqing Oilfield Company Ltd., Daqing, Heilongjiang, 163712 ChinaSearch for more papers by this authorYuewu SUN, Corresponding Author sunyuewu@jlu.edu.cn Key Laboratory for Evolution of Past Life and Environment in Northeast Asian (Jilin University), Ministry of Education, Changchun, 130026 ChinaCorresponding author. E-mail: sunyuewu@jlu.edu.cnSearch for more papers by this authorYanping HOU, Exploration and Development Research Institute of Daqing Oilfield Company Ltd., Daqing, Heilongjiang, 163712 ChinaSearch for more papers by this authorYudong JIN, Exploration and Development Research Institute of Daqing Oilfield Company Ltd., Daqing, Heilongjiang, 163712 ChinaSearch for more papers by this authorXin ZHANG, Exploration and Development Research Institute of Daqing Oilfield Company Ltd., Daqing, Heilongjiang, 163712 ChinaSearch for more papers by this authorTi LI, Exploration and Development Research Institute of Daqing Oilfield Company Ltd., Daqing, Heilongjiang, 163712 ChinaSearch for more papers by this author Chuanbiao WAN, Exploration and Development Research Institute of Daqing Oilfield Company Ltd., Daqing, Heilongjiang, 163712 ChinaSearch for more papers by this authorYunfei XUE, Exploration and Development Research Institute of Daqing Oilfield Company Ltd., Daqing, Heilongjiang, 163712 ChinaSearch for more papers by this authorYuewu SUN, Corresponding Author sunyuewu@jlu.edu.cn Key Laboratory for Evolution of Past Life and Environment in Northeast Asian (Jilin University), Ministry of Education, Changchun, 130026 ChinaCorresponding author. E-mail: sunyuewu@jlu.edu.cnSearch for more papers by this authorYanping HOU, Exploration and Development Research Institute of Daqing Oilfield Company Ltd., Daqing, Heilongjiang, 163712 ChinaSearch for more papers by this authorYudong JIN, Exploration and Development Research Institute of Daqing Oilfield Company Ltd., Daqing, Heilongjiang, 163712 ChinaSearch for more papers by this authorXin ZHANG, Exploration and Development Research Institute of Daqing Oilfield Company Ltd., Daqing, Heilongjiang, 163712 ChinaSearch for more papers by this authorTi LI, Exploration and Development Research Institute of Daqing Oilfield Company Ltd., Daqing, Heilongjiang, 163712 ChinaSearch for more papers by this author First published: 08 October 2020 https://doi.org/10.1111/1755-6724.14590AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onEmailFacebookTwitterLinked InRedditWechat No abstract is available for this article. Volume94, Issue5October 2020Pages 1718-1720 RelatedInformation

Viral Abundance and Diversity of Production Fluids in Oil Reservoirs.

Viruses are widely distributed in various ecosystems and have important impacts on microbial evolution, community structure and function and nutrient cycling in the environment. Viral abundance, diversity and distribution are important for a better understanding of ecosystem functioning and have often been investigated in marine, soil, and other environments. Though microbes have proven useful in oil recovery under extreme conditions, little is known about virus community dynamics in such systems. In this study, injection water and production fluids were sampled in two blocks of the Daqing oilfield limited company where water flooding and microbial flooding were continuously used to improve oil recovery. Virus-like particles (VLPs) and bacteria in these samples were extracted and enumerated with epifluorescence microscopy, and viromes of these samples were also sequenced with Illumina Hiseq PE150. The results showed that a large number of viruses existed in the oil reservoir, and VLPs abundance of production wells was 3.9 ± 0.7 × 108 mL−1 and virus to bacteria ratio (VBR) was 6.6 ± 1.1 during water flooding. Compared with water flooding, the production wells of microbial flooding had relative lower VLPs abundance (3.3 ± 0.3 × 108 mL−1) but higher VBR (7.9 ± 2.2). Assembled viral contigs were mapped to an in-house virus reference data separate from the GenBank non-redundant nucleotide (NT) database, and the sequences annotated as virus accounted for 35.34 and 55.04% of total sequences in samples of water flooding and microbial flooding, respectively. In water flooding, 7 and 6 viral families were identified in the injection and production wells, respectively. In microbial flooding, 6 viral families were identified in the injection and production wells. The total number of identified viral species in the injection well was higher than that in the production wells for both water flooding and microbial flooding. The Shannon diversity index was higher in the production well of water flooding than in the production well of microbial flooding. These results show that viruses are very abundant and diverse in the oil reservoir’s ecosystem, and future efforts are needed to reveal the potential function of viral communities in this extreme environment.

Sandbody architecture analysis of braided river reservoirs and their significance for remaining oil distribution: A case study based on a new outcrop in the Songliao Basin, Northeast China

The reservoir architecture analysis of braided rivers, especially falling-silt seam forms, has played a key role in predicting remaining oil distributions. However, no studies have used architecture analyses that document braided river outcrops and researched the tapping of the few remaining oil distributions based on outcrops in the Songliao basin, northeast China. In this paper, the architecture characteristics and remaining oil distribution of braided river reservoirs are studied using a combination of an outcrop, modern deposition and subsurface well data. The new 8–13 m thick Lower Cretaceous Quantou Formation outcrop of the Songliao basin is a braided fluvial succession arranged in one large fining-upward cycle. Eight facies (Gt, St, Sm, Sh, Sp, Sw, Fl and Fm), four architecture elements (CH, DA, LV, and FF), and three orders of bounding surfaces (third-, fourth-, and fifth-order) are recognized. A new distribution pattern of falling-silt seams and a braided river architecture model are presented according to the analysis of the outcrop. In the mid-channel bar, the falling-silt seams thin from the mid-bar to the bar tail following the flow direction. Each falling-silt seam is oriented tangentially to the basal surface of the mid-channel bar, and the upper falling-silt seam extends farther than the lower one. In a Daqing Oilfield exploitation block in the Songliao basin, while channels and bars are the main reservoir units, they have different remaining oil distribution patterns. For bars, water injection wells located at the mid-bar, zonal injection technology, the drilling of horizontal wells, and proper well patterns are proposed. Fourth-order bounding surfaces, single braided channels, stacking patterns, and the lateral blocking of levees and floodplains are the key factors affecting the remaining oil distribution in channels.

Impact of Oilfield Operating Cost Splitting Ratio on the Evaluation of Listed Developed Reserves

Proven reserves of oil and gas reflect the value of the oilfield and its future development. At present, the developed reserves of Daqing oilfield play an absolutely dominant role in the proved reserves. Under the condition of certain parameters, the economic limit yield plays a decisive role in the developed reserves, and the split ratio of operation cost is one of the key factors affecting the economic limit yield. The impact of operation cost splitting ratio on the evaluation of listed developed reserves is studied to provide support for the objective and reasonable evaluation of developed reserves in the future. Based on the formula of economic limit production, the relationship between economic limit production and operating cost splitting ratio of a single well is derived, and the effect of operating cost splitting ratio on the verified developed reserves under different oil prices is obtained. The results show that the change of operation cost splitting ratio under low oil price has great influence on the proved developed reserves.

Halomonas plays a central role in the syntrophic community of an alkaline oil reservoir with alkali-surfactant-polymer (ASP) flooding

Little is known about the microbial characteristics in oil reservoirs under alkali-surfactant-polymer (ASP)-flooding. In the present study, we collected two ASP-flooding samples and two nearby water-flooding samples from the Daqing oil field and performed 16S rRNA gene sequencing and metagenomic sequencing to fill this knowledge gap. The results indicated that the highly elevated pH resulted in a simple Euryarchaeotal community and a Halomonas &Nitrincola-dominated bacterial community in the production water of the alkaline oil reservoir. In addition, we hypothesized that multiple copies of genes encoding monovalent cation/proton antiporters in Halomonas and Nitrincola, and their facultative anaerobic and movable traits, were the adaptive mechanisms responsible for their competitive growth in the alkaline oil reservoir. We also revealed a unique syntrophic community in the alkaline oil reservoir and identified the central role of Halomonas within it. The present study revealed the microbial characteristics in an alkaline oil reservoir environment formed by ASP-flooding and indicated the application potential of Halomonas in AMP-flooding and microbial enhanced oil recovery (MEOR) technology to elevate the oil recovery rate from ASP-flooded oil reservoirs.

Automatic well test interpretation based on convolutional neural network for infinite reservoir

The well testing technique is an important tool in estimating well and reservoir characteristics, such as permeability, skin factor and so on. For a long time, researchers have been searching for automatic well testing interpretation tools, but the results are disappointing. This paper proposes using convolutional neural network (CNN) as an automatic well test interpretation approach for infinite acting reservoirs. The CNN takes pressure change and pressure derivative data of the log-log plot for inputs. The wellbore storage coefficient, skin factor and reservoir permeability are redefined into a dimensionless group CDe2S as the output of the CNN. In this method, the best trained CNN structure is obtained by minimizing mean square error (MSE) and mean relative error (MRE). This new method is tested for its effectiveness and accuracy in Daqing oil field, China. It demonstrates that, for wells in infinite reservoir, CNN could be an effective automatic well test interpretation technique. CNN also shows the potential for more complicated scenarios.

Synthesis of Poly(ethylene glycol) Grafted Polyamidoamine Dendrimer Hydrogels and Their Temperature and pH Sensitive Properties

PEG-based smart hydrogels have excellent properties and are widely used in the drug delivery, tissue engineering and other fields. In this article, a temperature responsive and pH sensitive dual responsive hydrogel which is suitable for water plugging and profile control in the Daqing oil field was prepared via graft copolymerization using polyethylene glycol (Mn = 600, 1000, and 2000) and polyamidoamine (PAMAM) as raw materials. The structure and properties of the products were characterized using infrared, 1H NMR and UV–Vis spectroscopy, end group titration, scanning electron microscopy (SEM) and swelling behavior tests. The influence of the molecular weight of the PEG precursor on the critical phase transition temperature (LCST) and pH sensitivity of the hydrogel were systematically studied. The experimental results showed that when the molecular weight of the PEG precursor was varied in the range of 600–2000, the hydrogel showed obvious temperature sensitivity and the LCST increased from 40 to 50°C. When the pH was in the range of 8–11, the hydrogel exhibited obvious pH sensitivity, swelling under alkaline conditions under acid shrinkage conditions, and the swelling ratio of the hydrogel increased upon increasing the molecular weight of the PEG precursor. The hydrogel was switched at temperatures between 10 and 60°C, pH values between 3 and 11, and the swelling behavior of the hydrogel showed good reversibility for swelling–deswelling, which provides the possibility for water plugging and profile control in an oil field. SEM showed that the hydrogels in their dry state had a spherical structure and as the molecular weight of the PEG precursor increased, the size of the spherical particles decreased and the porosity increased.

Hybrid Chemical Enhanced Oil Recovery Techniques: A Simulation Study

Simultaneous utilization of surfactant and preformed particle gel (henceforth; PPG) flooding on the oil recovery enhancement has been widely investigated as a preferable enhanced oil recovery technique after the polymer flooding. In this paper, a numerical model is developed to simulate the profound impact of hybrid chemical enhanced oil recovery methods (PPG/polymer/surfactant) in sandstone reservoirs. Moreover, the gel particle conformance control is considered in the developed model after polymer flooding performances on the oil recovery enhancement. To validate the developed model, two sets of experimental field data from Daqing oil field (PPG conformance control after polymer flooding) and Shengli oil field (PPG-surfactant flooding after polymer flooding) are used to check the reliability of the model. Combination of preformed gel particles, polymers and surfactants due to the deformation, swelling, and physicochemical properties of gel particles can mobilize the trapped oil through the porous media to enhance oil recovery factor by blocking the high permeable channels. As a result, PPG conformance control plays an essential role in oil recovery enhancement. Furthermore, experimental data of PPG/polymer/surfactant flooding in the Shengli field and its comparison with the proposed model indicated that the model and experimental field data are in a good agreement. Consequently, the coupled model of surfactant and PPG flooding after polymer flooding performances has led to more recovery factor rather than the basic chemical recovery techniques.

A Study on the Relationship between Oil Micro-occurrence State and Oil Source in Low Permeability Tight Sandstone Reservoir Based on Computer Technology - a Case Study of Daqing Oilfield

Well logging is a method of measuring earth parameters using a variety of geophysical properties. In oil fields, it is often referred to as field geophysical exploration, petroleum and mineral geophysical or geophysical logging. The use of logging technology can reduce the workload of drilling and coring, improve the exploration speed and reduce the cost of exploration, so it is widely used in oilfield development activities. This paper takes Daqing oilfield, the largest oilfield in China since 1960s, located in the middle of songliao plain, as an example, and analyzes the application of logging method based on computer technology in oilfield development.