Gudao Oilfield Research Articles

Ecological restoration evaluation of afforestation in Gudao Oilfield based on multi-source remote sensing data

The growing petroleum industry poses significant ecological challenges, prompting an increased focus on ecological restoration projects in onshore oilfields. Current efforts focus on revegetation in deforested oilfields, while research remains limited on alternative ecological restoration strategies aimed at establishing new ecosystems in oilfields. This study employed multi-source remote sensing data from 1985 to 2022 to calculate a remote sensing-based ecological index (RSEI) and constructed an integrated forest health index (IFHI), in order to evaluate the ecological restoration effects in the Gudao shelterbelt of Shengli Oilfield in the Yellow River Delta, and investigated the impact of oil extraction by considering forest phenology. The RSEI of the shelterbelt showed an upward trend and reached a Good level of ecological environment quality from 1990 to 2003, but it declined after that, indicating the potential of RSEI to quickly assess ecological restoration effects and guide management at different stages. Comparing the restoration effects of different tree species, a Robinia pseudoacacia L. (RP) and Fraxinus velutina Torr. (FV) mixed forest demonstrated the greatest capacity to improve environmental quality, with the most years (25 years) of the Good and Excellent levels and the highest IFHI value (1.52). In contrast, Ulmus pumila L. (UP) and Sophora japonica L. (SJ) were unsuitable for mixed planting for ecological restoration. The study also found that monospecific RP forests within 30 m of oil wells were significantly impacted by oil extraction (P ≤ 0.05), necessitating tailored forest management. The research aims to serve as a reference for ecological restoration in global onshore oil production areas, particularly in delta regions and sparsely vegetated areas.

Screening and field application of microbial-flooding activator systems

This study aims to further enhance the oil recovery of reservoirs in the Zhong-2 Block of the Gudao Oilfield by identifying the most effective microbial-flooding activator systems and applying them in the field. We began by analyzing the structure of the reservoirs' endogenous microbial communities to understand the potential impact of microbial flooding. This was followed by determining commonly used activator systems based on their abilities to stimulate oil-displacement functional bacteria. Through laboratory experiments on oil displacement efficiency and sweep characteristics, we determined the optimal activator injection method (injection ratio) and the requisite bacterial concentration for maximal microbial-flooding efficacy. Finally, we selected the optimal activator systems and applied them to field tests. Our findings suggest the target block is highly receptive to microbial-flooding. In terms of performance, the activator systems ranked as No. 3 > No. 4 > No. 1 > No. 2. Interestingly, a deep activator system, when compared to the top-performing No. 3 system, exhibited a higher bacterial concentration peak and longer peaking duration. Optimal oil displacement effects were observed at a 1:4 vol ratio between the No. 3 activator and deep activator systems, with bacterial concentrations of up to 106 cells/mL or above. Field tests with the selected activator systems, following a specific injection protocol, demonstrated a notable increase in oil production and a reduction in water cut.

Production characteristics and displacement mechanisms of infilling polymer-surfactant-preformed particle gel flooding in post-polymer flooding reservoirs: A review of practice in Ng3 block of Gudao Oilfield

The pilot test of infilling polymer-surfactant-preformed particle gel (PPG) flooding has been successfully implemented after polymer flooding in Ng3 block of Gudao Oilfield in China. However, the production characteristics and displacement mechanisms are still unclear, which restricts its further popularization and application. Aiming at this problem, this paper firstly analyzes the production performance of the pilot test and proposed four response types according to the change of water cut curves, including W-type, U-type, V-type response, and no response. Furthermore, the underlying reasons of these four types are analyzed from the aspects of seepage resistance and sweep efficiency. The overall sweep efficiency of gradual-rising W-type, gradual-decreasing W-type, and early V-type response increases from 0.81 to 0.93, 0.55 to 0.89, and 0.94 to 1, respectively. And the sum of seepage resistance along the connection line between production well and injection well for U-type and delayed V-type response increases from 0.0994 to 0.2425, and 0.0677 to 0.1654, respectively. Then, the remaining oil distribution after polymer flooding is summarized into four types on the basis of production and geological characteristics, namely disconnected remaining oil, streamline unswept remaining oil, rhythm remaining oil, and interlayer-controlled remaining oil. Furthermore, the main displacement mechanisms for each type are clarified based on the dimensionless seepage resistance and water absorption profile. Generally, improving connectivity by well pattern infilling is the most important for producing disconnected remaining oil. The synergistic effect of well pattern infilling and polymer-surfactant-PPG flooding increases the dimensionless seepage resistance of water channeling regions and forces the subsequent injected water to turn to regions with streamline unswept remaining oil. The improvement of the water absorption profile by polymer-surfactant-PPG flooding and separated layer water injection contributes to displacing rhythm remaining oil and interlayer-controlled remaining oil. Finally, the paper analyzes the relationships between the remaining oil distribution after polymer flooding and production characteristics of infilling polymer-surfactant-PPG flooding. The study helps to deepen the understanding of infilling polymer-surfactant-PPG flooding and has reference significance for more commercial implementations in the future.

Dynamic Evaluation of Flow Unit Based on Reservoir Evolution: A Case Study of Neogene Guantao Ng3 Formation in M Area, Gudao, Bohai Bay Basin

To clarify the dynamic evolution characteristics of reservoir flow units during water injection development, the upper member of the Neogene Guantao formation in Block M of Gudao Oilfield is taken as a case study. Based on logging data, water injection profile test data, subwell data, and production performance data, among others, the flow zone index (FZI static) was proposed as the static evaluation parameter of the flow unit. The relationship between cumulative water injection (WT) and FZI change ( △ FZI ) was fitted. Hence, the △ FZI caused by water injection is combined with the static parameter of flow unit evaluation (FZI static) as the dynamic parameter of flow unit evaluation (FZI dynamic). The comprehensively evaluated reality of flow units in different periods is characterized by formula FZI static + △ FZI = FZI dynamic . The study shows that as the division standard of the flow unit, the FZI has a good correlation with the test results of the water absorption profile, such as water absorption intensity and relative water injection volume. Using the FZI as the static parameter of flow unit evaluation, four types of flow units were divided as follows: type I flow unit, FZI ≥ 4.1 ; type II flow unit, 4.1 > FZI ≥ 2.4 ; type III flow unit, 2.4 > FZI ≥ 1.7 ; type IV flow unit, 1.7 > FZI . The reservoir porosity and permeability characteristics of different flow units are highly correlated. Moreover, the relative permeability curve confirms that different flow units have different seepage capacities. Though, comparing characteristic reservoir parameters in different periods, the reservoir’s physical parameters became more conducive to fluid flow with the water injection development. The increase in the same water injection rate for type I and II flow units was greater than that for type III and IV flow units. Furthermore, when type I flow units were continuously distributed in a large area, high water consumption bands were formed, absorbing most of the water injection in the water injection wells. Hence, the waterflood efficiency was low. The change in different flow units was mainly controlled by the injection production well pattern and WT. Combined with the relative change characteristics of interlayer flow units, the changes can be divided into increasing type change and decreasing type changes. Finally, according to the distribution characteristics of different flow units, oil saturation, and water flooding results, strategies for tapping the potential of the remaining oil from three aspects (plane, interlayer, and inner layer) were formulated.

Flow field characterization and evaluation method based on unsupervised machine learning

Long-term water flooding can be inefficient due to imbalanced displacement, resulting in sub-optimal recoveries. Therefore, the quantitative characterization and evaluation method of the flow field is significant for further development and adjustment. In this study, based on streamline simulation results, decoding rules were formulated to extract streamline data. Considering the attribute feature of each node along the streamline, flow field characterization indices were constructed. And combining the fast density peaks clustering (FDPC) algorithm and silhouette coefficient (SC), a novel flow field evaluation method based on streamline clustering was proposed. Results indicated that the invalid water circulation channels and areas with developing potential in reservoirs can be identified. Besides, the distribution of flow field can also be observed, and the characteristics of the identified region can be analyzed, which provides a basis for the subsequent flow field adjustment. Meanwhile, streamlines between injection and production wells can be subdivided to describe the distribution of water displacement capacity. Based on the evaluation results of streamline clustering, Gudao oilfield adjusted the flow field through injection-production adjustment, which effectively improved the development effect of the block and increased the recovery degree from 50.3% to 52.4%. This work provides an effective evaluation method to directly characterize the displacement changes for underground flow field, and it is of great significance for the decision-making of water flooding structure adjustment and optimization.

Characteristics of Seepage Barriers in Fluvial Reservoirs of Meandering Rivers and Their Impacts on Water Injection Development: A Case Study of Neogene Guantao Formation in Block M, Gudao Oilfield

To deepen our understanding of reservoir heterogeneity, seepage barriers in the study area were divided into interlayer, intralayer, and planar levels based on their spatial distribution characteristics and then investigated by taking the third member of the Neogene Guantao Formation in the block M of the Gudao oilfield as an example. Based on their genesis characteristics, the interlayer seepage barriers were divided into the overbank sand-overbank sand type, overbank sand-channel type, isolated channel superposition type, and channel shallow-cut type. The planar seepage barriers were categorized into the channel boundary type, abandoned channel type, channel-overbank sand type, and floodplain mudstone type. The intralayer seepage barriers were classified into the mudstone type and physical property type. Classifying multiple levels of different types of seepage barriers led to the refinement of their spatial characteristics. The strength of seepage barriers was characterized using the “seepage barrier coefficient” and “reservoir quality coefficient,” and the small-valued coefficients of the interlayer and intralayer seepage barriers indicated that these seepage barriers are characterized by large thickness, high mudstone content, poor physical properties, and weak seepage ability. The strength of the planar seepage barriers was dependent on the sedimentary facies types and channel stages, and the difference between planar seepage barriers was characterized using the reservoir quality coefficient. The seepage barriers were described based on the multilevel classification of seepage barrier categories, the intralayer seepage barriers with a lateral accretion pattern in the meandering river point bars were identified and described, and the distribution characteristics of seepage barriers were summarized at multiple levels. The method of “hierarchical analysis, skeleton construction, and category fitting” was used to establish 3D models of different levels of seepage barriers, and a modeling method based on the characteristics of intralayer seepage barriers under the constraint of architecture pattern was used to model intralayer seepage barriers with a lateral accretion pattern. In the monitoring of water injection profiles, it was found that the extent of blockage achieved by seepage barriers affects the water injection volume and thus controls the fluid transport pattern. Due to the development characteristics of the seepage barrier in the formation, there are some differences in injection production efficiency under different well pattern matching modes. The research on the distribution characteristics of different levels of seepage barrier categories provides a reliable geological basis for improving the injection-production relationship.

Study on Dynamic Evolution Characteristics of Reservoir Flow Unit During Water Injection Development ——Taking the Upper Member of Neogene Guantao Formation in Region M of Gudao Oilfield as an Example

Study on Dynamic Evolution Characteristics of Reservoir Flow Unit During Water Injection Development ——Taking the Upper Member of Neogene Guantao Formation in Region M of Gudao Oilfield as an Example

Research on meandering river reservoir deposition architecture and 3D modeling of the Gudao Oil field in the Bohai Bay Basin

The distribution of remaining oil is controlled by internal sand body heterogeneity in the middle and late stages of oil field development. Reservoir architecture analysis has been conducted in the third sand group in the Guantao Formation of the Gudao Oil field. Different scales of reservoir architecture units have been identified, including complex meandering river belt, single meandering river belt, single point bar and inner point bar. Four different single channel signatures have been found in the research area to identify the single channel belt. The single point bar has been distinguished based on point bar development characteristics. The architecture of the inner point bar has been analyzed based on subsurface well data and empirical formulas. The lateral accretion angle of the muddy layer ranges from 5° to 8°, the interspace between lateral accretion muddy layers ranges from 20 to 35 m, and the horizontal width of a single lateral accretion sand body is 55–120 m. Based on the above-mentioned reservoir architecture analysis, a reservoir architecture model has been established using the hierarchical modeling method. A three-dimensional porosity and permeability model has been developed within architecture model constraints and could provide a reliable geological template for oil field development and production.

Complete genome sequence of the novel thermophilic polyhydroxyalkanoates producer Aneurinibacillus sp. XH2 isolated from Gudao oilfield in China

Aneurinibacillus sp. XH2 (CGMCC 1.15535) was isolated from Gudao oilfield in China. It is able to use simple carbon resources to accumulate Polyhydroxyalkanoates (PHAs) in a thermophilic fashion. Here, we describe the genomic features of this strain. The total genome size of Aneurinibacillus sp. XH2 is 3,664,835bp and contains 3441 coding sequences and 114 tRNAs. The annotated genome sequence of this strain provides the genetic basis for revealing its role as a themophilic PHAs producing bacterium.

Thermophilic production of polyhydroxyalkanoates by a novel Aneurinibacillus strain isolated from Gudao oilfield, China.

Polyhydroxyalkanoates (PHAs) are usually biosynthesized using mesophilic strains, but the fermentation processes often suffer from bacterial contamination. This work reports the screening of thermophilic bacteria capable of producing PHAs under elevated temperatures to reduce the contamination risk. Strain XH2 was isolated from an oilfield and identified as Aneurinibacillus sp. by morphology, physiological-biochemical characterization, and 16S rDNA phylogenetic analysis. This strain can produce PHA granules, which was detected by Nile red staining and transmission electron microscopic imaging. At 55 °C, 111.6 mg l(-1) of PHA was produced in a fermentation medium containing glucose, peptone, and yeast extract. If peptone was removed from the medium, the yield of PHA would be enhanced by 2.4 times. The main monomers of the PHA product were identified to be 3-hydroxybutyrate and 3-hydroxyvalerate with a molar ratio of 17.2:1 by gas chromatography-mass spectroscopy (GC-MS) and nuclear magnetic resonance analyses. Two minor homologues, 3-hydroxyoctanoate, and 3-hydroxy-4-phenylbutanoate, were tentatively identified by GC-MS as well. This is the first report of thermophilic PHA bacterial producer from the Firmicutes phylum.

Land Subsidence over Oilfields in the Yellow River Delta

Subsidence in river deltas is a complex process that has both natural and human causes. Increasing human activities like aquaculture and petroleum extraction are affecting the Yellow River delta, and one consequence is subsidence. The purpose of this study is to measure the surface displacements in the Yellow River delta region and to investigate the corresponding subsidence source. In this paper, the Stanford Method for Persistent Scatterers (StaMPS) package was employed to process Envisat ASAR images collected between 2007 and 2010. Consistent results between two descending tracks show subsidence with a mean rate up to 30 mm/yr in the radar line of sight direction in Gudao Town (oilfield), Gudong oilfield and Xianhe Town of the delta, each of which is within the delta, and also show that subsidence is not uniform across the delta. Field investigation shows a connection between areas of non-uniform subsidence and of petroleum extraction. In a 9 km2 area of the Gudao Oilfield, a poroelastic disk reservoir model is used to model the InSAR derived displacements. In general, good fits between InSAR observations and modeled displacements are seen. The subsidence observed in the vicinity of the oilfield is thus suggested to be caused by fluid extraction.

English

A novel phenol-degrading bacterium named as SKDP-1 was isolated from crude oil contaminated soil, Gudao oil field in the Northeast of Shandong Dongying, East China. The biochemical tests indicated that strain SKDP-1 was Gram-negative, and glucose and citrate could be utilized and starch not gelatin. Both Voges-Proskauer and H2O2 enzyme tests were positive. The activities of catechol 1,2-dioxygenase (C12O) and catechol 2,3-dioxygenase (C23O) in free cells were measured to be 8 and 91 IU, respectively. 16S rDNA gene sequences of strain SKDP-1 analysis showed the similarity of 98% with Pseudomonas putida (）AB680847). The phylogenetic tree formed by 16S rDNA sequences from both strain SKDP-1 and its most related bacteria also proved strain SKDP-1 to be one member of the genus Pseudomonas. Strain SKDP-1 showed the high phenol-degrading rates from 30 to 99% cultured by mineral salts medium (MSM), which was added with phenol from 100 to 1600 mg/L, respectively. The optimum pH and growth temperature for strain SKDP-1 to remove phenol were about 7.0 and 30°C, respectively. Based on its biochemical properties and high capability of degrading phenol, strain SKDP-1 provided the possibilities of treating phenol contaminated environment in the future.   Key words: Phenol degradation, Pseudomonas, ortho-cleavage pathway.

Study and Application of Design Optimization of Horizontal Wells in a Thick Positive Rhythm Oil Layer

Remaining oil is enriched at the top of the thick positive rhythm oil layer during the ultra-high water cut stage. While the conventional vertical wells cannot produce good development for such remaining oil, the horizontal wells can bring effective results. In this study, typical well groups were selected from the Gudao Oilfield, and a geological model was established. By using the reservoir simulation technology, the design of horizontal wells was optimized under the current vertical well pattern, and the energy supply manners for horizontal wells were optimized. The research results were applied to oilfield development, and good development effects have been obtained.

Research of Guantao Thick Oil Reservoir Contrast Model in Gudao Oilfield

Southwest Gudao oilfield of heavy oil reservoir characteristics is complex, the fine reservoir division and correlation for increase in oil reserve and production is of great significance. According to the reservoir multi-level contrast method, will study area Ng5-6 sandstone group is divided into 11 small layer, 14 deposit time unit, and to establish a comparison model of reservoir. Reservoir contrast results and its application effect is good, improve the research area of thick oil development effect, and the economic benefit is remarkable.

Physical simulation and fine digital study of thermal foam compound flooding

Abstract According to the similarity criterion of 3D physical simulation of thermal recovery, experimental parameters of 3D physical simulation of steam flooding and thermal foam compound flooding in extra-heavy oil reservoirs of the Gudao Oilfield were calculated, and relevant experiments were carried out. Based on the experimental results, 3D fine numerical simulation was carried out to analyze the steam flooding and thermal foam compound flooding in heavy oil reservoirs. The results show that thermal foam compound flooding could effectively inhibit steam channeling and improve sweep efficiency, and thus enhance the oil recovery in heavy oil reservoirs after steam flooding. Technological parameters of thermal foam compound flooding were optimized according to the results of fine numerical simulation. The optimum injection method is foam-slug injection, the optimal steam injection rate is 25 mL/min, nitrogen injection rate is 1 000 mL/min (standard conditions), the time of foam-slug injection is 1.0 min and the interval between foam-slugs is about 10-20 min during thermal foam-slug injection. At last, the similarity criterion was employed for inversion calculation of the optimization results. Based on the results, optimal field injection and production parameters can be confirmed. The ultimate recovery ratio of thermal foam compound flooding in super-heavy oil reservoirs could reach 42.15%, which is 12.50% higher than steam flooding.

Petroleum Sulfonates as Oil Displacement Agent and Application

In terms of the condition of injection water after polymer flooding of Gudao oilfield, the following water quickly broke though the bank to the production wells, while most of residual oil remains in the formation. To solve the problem, two kind of petroleum sulfonates made in China are selected to form oil displacement agent (ODA) solution. The petroleum sulfonate available for crude oil of Gudao oilfield with the ultra-low interfacial tension is found by drawing an oil/water interfacial tension contour diagram. The results show that the interfacial tension can be lower than 3.6×10-4mN/m when the active agent contained with 0.25%KPS+0.225%APS, and the agent reduces water resistance of entering the hole to improve sweep coefficient and oil displacement efficiency. The existence of the polymer has no influence on the balanced value of interfacial tension, but just delays the interfacial tension to reach the balance. Pouring into 0.3 pore volume (PV) high-efficient ODA can improve 17% oil recovery. Synergistic effect of two kind of petroleum sulfonate with low cost to enhance oil recovery will have a great prospect for enhanced oil recovery (EOR)

Study of the Plugging of Oil Well Sand Control Area in a Polymer Flooding Region

The plugging of the oil well sand control area in a polymer flooding region was studied and the plugging substances were analyzed through UV-Vis spectrophotometer analysis, plasma emission spectrometry analysis, laser particle size analysis, X-Ray Diffractometer (XRD) analysis, microscopic observation, chromatograph-mass spectrometer, etc. It is inferred that the main reason for the plugging of the sand control area was the adsorption, gathering and bridging of PAM on the surface of the sand. The migration of the mineral fines from the stratum and the adsorption of the crude oil ingredients on the surface of the fines also result in plugging. An experimental study on the polymer degradation was performed and two types of plug removal agents, potassium persulfate and sodium thiosulfate, were selected and tested. It showed that potassium persulfate and sodium thiosulfate could degrade the plugging substances and recover core permeability effectively. Moreover, field application tests were conducted in Gudao oil field which showed the restoration of the performance of various wells. It also indicated that the injection pressure obviously decreased and liquid production per day increased greatly after application of the plug removal agents in the sand control area.

Gudao Oilfield Fault Seal Ability Research and Development of Oil and Gas Application

In Gudao Oilfield Southwest margin area, fault seal ability to determined under Guantao formation study reservoirs distribution has a very important significance. Through the research fault two plates of lithology relation, mudstone daub analysis, fault zone fillings argillaceous content analysis of the gender influence factors of study area, main fault sealing ability analysis results show that upper Guantao formation and under Guantao formation7, 8 sand formation fault seal ability is good, beneficial to the forming reservoirs; Under Guantao formation8 sand formation the following fault seal ability is bad, and can be used for oil and gas migration channels.

Microbial Diversity of Guantao-3 Member of Zhongyi Block, Gudao Oil Field in China*

To develop microbial enhanced oil recovery(MEOR) technology,microbial diversity of Guantao-3 Member of Zhongyi Block,Gudao Oil Field in China after water and chemical flooding was investigated by molecular biology methods. Two samples of injected water and four samples of produced water were analyzed. The results indicated the diverse of microbial communities in the injected water,which was dominated by Gammaproteobacteria and Betaproteobacteria,was more complicated than that in produced water,and the data also showed that there were notable differences of microbial communities in different oil wells,and the microbial community in a single well also changed with the time courses. Besides,the species diversity of bacteria in produced water,which was dominated by Gammaproteobacteria,was relatively simple;while that of archaea was relatively rich,including Methanobacteria,Methanomicrobia,Archaeoglobi and Thermococci. These results provide the basis information on microbial ecology in specific reservoirs for MEOR technology.

Petroleum Sulfonates as Oil Displacement Agents and Application to Gudao Oil Field

In terms of the condition of injection of water after polymer flooding of the Gudao oil field (Shengli, China), the following water quickly broke though the bank to the production wells, while most of residual oil remained in the formation. To solve the problem, two types of petroleum sulfonates made in China were selected to form an oil displacement agent (ODA) solution. The petroleum sulfonate available for crude oil from the Gudao oil field with the ultra-low interfacial tension can be found by drawing an oil/water interfacial tension contour diagram. The results show that the interfacial tension can be lower than 3.6 × 10−4 mN/m when the active agent is contained with 0.25% Kelamayi petroleum sulfonate (KPS) + 0.225% Anqing petroleum sulfonate (APS) and if the agent reduces water resistance by entering the tiny pore to improve sweep coefficient and oil displacement efficiency. The polymer has no influence on the balanced value of interfacial tension but delays the interfacial tension to reach the balance. Pouring 0.3 pore volume (PV) high-efficient ODA into reservoir can improve 17% oil recovery (OR). Synergistic effects of two types of petroleum sulfonate with low cost to enhance OR will have an excellent prospect for enhanced oil recovery (EOR).