Shengli Oilfield Research Articles

A fracture conductivity model for channel fracturing based on lattice-Boltzmann-method and computational-fluid-dynamics

This paper introduces a new method to predict fracture conductivity for channel fracturing by lattice-Boltzmann-method (LBM) and computational-fluid-dynamics (CFD). Firstly, the deformation of the proppant pillar is tested using uniaxial compression experiments. A non-uniform fracture width model considering the nonlinear deformation of fracture and the embedment of proppant pillars is established. Then, an improved model based on LBM-CFD is proposed to simulate the flow field within the fracture and calculate the fracture conductivity. Finally, parametric analysis is carried out to understand the effects of closure stress, elastic modulus of the reservoir rock, proppant pillar's shape and proppant pillar's spacing on fracture width and conductivity. The results showed that the conductivity decreases gradually with closure stress and increases with elastic modulus. The proppant pillar with the smallest shape ratio can provide the highest conductivity. When the ratio of the proppant pillar's diameter to spacing is about 0.5, the conductivity for channel fracturing is best. The time of proppant-laden fluid (PLF) pulse and proppant-free fluid (PFF) pulse are the keys to the successful implementation of channel fracturing. The simulation results have been applied to the optimization of the pulse time in Shengli Oilfield. The field application proves that channel fracturing design based on our method could result in a large increase in well production. This paper gives critical insights for predicting the conductivity for channel fracturing, which could serve as guidelines for the optimization of proppant pillar's parameters and pulse time in channel fracturing design.

Aeration desulfurization of offshore oilfield produced water used for preparation of polymer solutions

It is an inevitable trend to reuse treated oilfield produced water to prepare polymer solutions due to the shortage of freshwater resources in offshore platforms. The presence of S2− in produced water reduces the viscosity of the prepared polymer solution, which proves unfavorable for oil displacement. In this study, the aeration and sedimentation techniques were employed to desulphurize the produced water of an offshore oilfield in the Shengli Oil Field. The oxygen mass transfer coefficient was directly proportional to the aeration rate and the concentration of micromolecular organics, but inversely proportional to the concentration of petroleum hydrocarbons. Raising the air-water ratio from 0.1 to 2 increased the removal rate of S2− from 16% to 100%. The high temperature of produced water could enhance the oxidation of S2−, the products of which principally comprised elemental sulfur and thiosulfate at a low air-water ratio, but sulfate and sulfite at a higher ratio. An 8 h static sedimentation of the aerated produced water led to a significant decrease in the concentration of dissolved oxygen (DO), which was consumed by the low-valence sulfur-containing substances and reactive organic matters. When the hydraulic retention time was 20 min and the air-water ratio was 1, both S2− and DO were not detected in the produced water after sedimentation, which was qualified for confection of polymer solutions. Findings in this research is expected to provide a theoretical basis for optimization of parameters in the processes of aeration and sedimentation.

The metabolism of pyrene by a novel Altererythrobacter sp. with in-situ co-substrates: A mechanistic analysis based on pathway, genomics, and enzyme activity

Using co-substrates to enhance the metabolic activity of microbes is an effective way for high-molecular-weight polycyclic aromatic hydrocarbons removal in petroleum-contaminated environments. However, the long degradation period and exhausting substrates limit the enhancement of metabolic activity. In this study, Altererythrobacter sp. N1 was screened from petroleum-contaminated soil in Shengli Oilfield, China, which could utilize pyrene as the sole carbon source and energy source. Saturated aromatic fractions and crude oils were used as in-situ co-substrates to enhance pyrene degradation. Enzyme activity was influenced by the different co-substrates. The highest degradation rate (75.98%) was achieved when crude oil was used as the substrate because strain N1 could utilize saturated and aromatic hydrocarbons from crude oil simultaneously to enhance the degrading enzyme activity. Moreover, the phthalate pathway was dominant, while the salicylate pathway was secondary. Furthermore, the Rieske-type aromatic cyclo-dioxygenase gene was annotated in the Altererythrobacter sp. N1 genome for the first time. Therefore, the co-metabolism of pyrene was sustained to achieve a long degradation period without the addition of exogenous substrates. This study is valuable as a potential method for the biodegradation of high-molecular-weight polycyclic aromatic hydrocarbons.

Oil spill modeling of Chengdao oilfield in the Chinese Bohai Sea

Offshore oil exploration and development is faced with complex operational conditions and harsh environments. Once an oil spill occurs, it will cause serious damage to the marine ecological environment. The Chengdao oilfield is located in the south of the Chinese Bohai Sea, which is an important oil production area of the Shengli oilfield. At present, the trajectories and fate of spilled oil under complex marine conditions are still unclear and the potential impacts in different areas of the Chengdao oilfield are unknown. Aiming to solve the above problems, this paper carries out numerical simulations of oil spills in the Chengdao oilfield. The hydraulic model of the Chengdao oilfield is constructed and its accuracy is evaluated against tide level and tidal current data from different ports along the coast. By coupling the hydrodynamic field and wind field, an oil spill model of the Chengdao oilfield considering weathering effects could be constructed. The effects of hydrodynamic factors and environmental factors on an oil spill in the Chengdao oilfield are studied. Weathering processes such as evaporation and emulsification are considered in the simulations. The research results can provide theoretical and technical support for the emergency responses to the oil spills in the Chengdao oilfield.

Interwell connectivity inversion method of steam flooding: Based on an analytical model and genetic algorithm

The steam channeling between wells of steam flooding in heavy oil reservoirs is an important factor impacting the development effect. Interwell connectivity is a key indicator for analyzing and predicting steam channeling. At present, only the correlation between injection and production is used to analyze the interwell connectivity, and the variation characteristics of liquid production and bottom hole temperature are not comprehensively considered to achieve the quantitative prediction of interwell connectivity in steam flooding. In this paper, based on the mass-conservation equation and energy-conservation equation, the analytical-calculation model of liquid production and bottom hole temperature of steam flooding in one injection well and one production well model is established. The ‘interwell connectivity coefficients’ are used as the splitting parameter of injected steam to each production well, and the analytical-calculation model of multiwell injection-production is extended. Taking the minimum mean square deviation of the error between the liquid production and bottom hole temperature as the objective function, the genetic algorithm is used to fit the liquid production and bottom hole temperature, and the ‘interwell connectivity coefficients’ of steam flooding are inverted. The innovation of this method lies in the establishment of analytical models of multiwell injection-production fluid production and bottom hole temperature and the establishment of a variable weight function in the objective function, which improves the accuracy of interwell connectivity inversion of steam flooding. Utilizing reservoir numerical simulation technology, the accuracy of the method is verified by synthetic models of homogeneous and high-permeability channels. The method is applied to the steam flooding reservoir of the Ng5 unit in Zhongerbei, Shengli Oilfield, China. The interwell connectivity of the two steam flooding well groups is inverted, and the results are consistent with the tracer analysis results. The findings of this study can help for better understanding of the geological conditions of the steam flooding reservoirs, and provide guidance for the selection of the next development plan.

Long-term study on electrophysiological characteristics and catheter ablation of idiopathic ventricular arrhythmias originating from the left ventricular posterior papillary muscles guided by intracardiac ultrasound.

BackgroundThis study aimed to investigate the electrophysiological characteristics of idiopathic ventricular arrhythmias (VAs) originating from the left ventricular posterior papillary muscles (LPPM) and explore the efficiency of catheter ablation using three‐dimensional intracardiac ultrasound technology.MethodsTwenty‐seven cases of premature ventricular contraction/ventricular tachycardia (PVC/VT) originating from the left ventricular posterior papillary muscles were recorded from July 2015 to June 2019 in the Central Hospital of Shengli Oil Field and the First Affiliated Hospital of Zhengzhou University. Electrophysiological mapping and radiofrequency catheter ablation (RFCA) were performed using three‐dimensional intracardiac ultrasound technology. The characteristics of the body surface and intracavity electrocardiogram were analyzed. All cases were followed up for 24 months after the operation.ResultsThe VAs of all 27 cases were successfully eliminated by catheter ablation. QRS complexes were observed with a right bundle branch block (RBBB) pattern and a steep slope in the initial segment. Lead I appeared with an Rs pattern, and inferior leads (lead II, III, and aVF) were usually with an S wave. The lead aVR appeared with a qR pattern, while the R wave was commonly found in aVL. The main wave in leads V1‐V3 was positive but negative in V5 and V6.ConclusionVentricular arrhythmias originating from the left ventricular posterior papillary muscles have similar electrophysiological characteristics. The origin site was accurately located using three‐dimensional intracardiac ultrasound technology. Catheter ablation effectively eliminated VAs.

Study on corrosion characteristics of Q235 steel in seawater, soil and dry-wet alternating environments focusing on Shengli oilfield

The coastal pipelines are the key link between the offshore and the onshore pipelines, which are located in the soil dry-wet alternating environment. Even though higher corrosion risk of metals in coastal soil dry-wet alternating environment, few papers focused on this condition, while much research about ocean and atmospheric dry-wet alternating environment was paid attention to. In this paper, a self-designed soil dry-wet alternating experimental device was used to investigate the corrosion characteristics of Q235 steel in seawater, soil and dry-wet alternating environment based on mass loss experiments, corrosion morphology analysis and electrochemical experiments. The results showed that the general corrosion rate of Q235 steel in soil and seawater environments basically remained unchanged, and in dry-wet alternating environment increased with time, while the pitting rates were 0.280 mm/a (soil), 0.420 mm/a (seawater) and 0.567 mm/a (dry-wet alternation), respectively, which was caused by the oxygen concentration cell and salt concentration cell. Meanwhile, the growth rate of pitting size in dry-wet alternating environment was much higher than that in the other two environments with different corrosion characteristics of pitting corrosion (seawater and dry-wet alternation) and a changed from general corrosion to pitting corrosion (soil). In three environments, the corrosion current density (I corr) increased, in which on the 30th day of experiment, I corr = 79.72 μA cm−2 in dry-wet alternating environment, which was much higher than I corr = 47.89 μA cm−2 in seawater environment. In dry-wet alternating environment, the mass diffusion impedance at 10–2 Hz and the maximum phase angle changed significantly, while the logf-log∣Z∣ curve in low-middle frequency decreased significantly, and charge transfer resistance at 105 Hz reduced from 10.4 Ω to 4.3 Ω, illustrating an increasing corrosion rate.

Fingerprint analysis reveals sources of petroleum hydrocarbons in soils of different geographical oilfields of China and its ecological assessment

The distribution and characteristics of petroleum in three different geographic oilfields in China: Shengli Oilfield (SL), Nanyang Oilfield (NY), and Yanchang Oilfield (YC) were investigated. The average concentration of the total petroleum hydrocarbons (TPHs) conformed to be in the following law: SL Oilfield > NY Oilfield > YC Oilfield. Fingerprint analysis on the petroleum contamination level and source was conducted by the geochemical indices of n-alkanes and PAHs, such as low to high molecular weight (LMW/HMW) hydrocarbons, n-alkanes/pristine or phytane (C17/ Pr, C18/Ph), and ratio of anthracene/ (anthracene + phenanthrene) [Ant/(Ant + Phe)]. Soils adjacent to working well oils indicated new petroleum input with higher ratio of low to high molecular weight (LMW/HMW) hydrocarbons. The oil contamination occurred in the grassland soils might result of rainfall runoff. Petroleum source, petroleum combustion source, and biomass combustion were dominant PAHs origination of soils collected from oil exploitation area, petrochemical-related sites, farmland and grassland, respectively. The suggestive petroleum control strategies were proposed in each oilfield soils. Ecological potential risk of PAHs was assessed according to the toxic equivalent quantity (TEQ) of seven carcinogenic PAHs. The results showed that high, medium, and low ecological risk presented in petro-related area, grassland soils, and farmland soils, respectively. High ecological risk was persistent in abandoned oil well areas over abandoned time of 15 years, and basically stable after 5 years. This study can provide a critical insight to ecological risk management and source control of the petroleum contamination.

Origin and Evolution of Geofluids in the Eocene Red-Bed Sandstones of the Dongying Depression, China

Fluid inclusion and petrographic study focused on authigenic quartz, annealed microfractures in quartz grains (AMF) and carbonate cement, was performed in red-bed reservoir sandstones from the first member of the Kongdian Formation and the lower fourth member of the Shahejie Formation (Shengli oilfield, East China). Both hydrocarbon and aqueous inclusions are present. Microthermometry and Laser Raman spectroscopes of liquid-rich two-phase inclusions showed that the pressure-correction value of aqueous inclusions is < 15°C. Differences in homogenization temperature and salinity occur between inclusions in quartz and carbonate cements. The liquid-rich two-phase aqueous inclusions were classified into four groups based on the salinity-homogenization temperature plots. The liquid-rich two-phase hydrocarbon inclusions were classified into two groups. The timing of the first-stage diagenetic fluid was before 31.3Ma. Fluids were from syn-depositional water and diagenetic fluids of clay minerals in interbedded mudstones. The timing of the second-stage diagenetic fluid was between 31.3 and 26.4Ma. Fluids were rich in organic acids and were accompanied by filling of small amounts of low maturity oil. The timing of the third-stage diagenetic fluid was between 26.4 and 21.4Ma. Fluids were mainly influenced by dehydration of gypsum-salt rocks and decarboxylation of organic acids. The timing of the fourth-stage diagenetic fluid was after 21.4 Ma. Fluids were influenced by organic acids and carbon acids and were accompanied by filling of mature oil after 10Ma. During the burial history, the red-bed reservoirs experienced the evolution process of early alkaline diagenetic fluids, early acid diagenetic fluids, late alkaline diagenetic fluids and late acid diagenetic fluids, which caused the alternate evolution of multiple alkaline and acid diagenetic environments.

Effect of temporary plugging agent concentration and fracturing fluid infiltration on initiation and propagation of hydraulic fractures in analogue tight sandstones

Temporary plugging agent (TP) fracturing has been widely used in many cases as an efficient technology to improve well production performance. In particular, the initiation and propagation of hydraulic fractures are vital to the evaluation of fracturing effect. Hence, the research of its influencing factors and laws is crucial for successful design of fracturing operation. As a productive research method, TP fracturing laboratory experiments have been broadly applied by innumerable scientists. Despite of the great achievements, those experiments mainly focus on the plugging ability of TP in unconsolidated and high permeability reservoirs in order to promote initiation and refracturing. However, studies are limited in light of tight low permeability reservoirs, in which TP not only function in plugging but also achieves changing the induced stress field. Especially for tight sandstone reservoirs, TP concentration and fracturing fluid infiltration are key factors affecting the initiation and propagation of hydraulic fractures of tight sandstones, and the laws have not been fully mastered. In this work, we poured artificial analogue rock samples (AARS) according to physical and mechanical parameters of tight sandstone reservoir in Shengli Oilfield, China. And true triaxial TP fracturing experiments under different TP concentrations were carried out on AARS. Aided by nano-organoboron crosslinking agent (NBC) and sleeves, different fracturing fluid infiltrations were achieved with the acoustic emission (AE) system monitoring the initiation and propagation of hydraulic fractures. In addition, the injection pressure curves, the geometries, forms and propagation process of hydraulic fractures were investigated in detail. The results show that: TP accretion, fracturing fluid infiltration and hydraulic fractures generation can produce innumerable AE energy that matches with the fluctuating injection pressure. TP fracturing leads to extension pressure higher than initiation pressure and slow down fracturing rate at relatively low TP concentration. TP concentration is positively correlated with both initiation pressure and average pressurization rate, but negatively correlated with the time for initiation, and such regularity is better reflected in weaker infiltration. 1.2% is the optimal TP concentration to increase initiation pressure and shorten the time for initiation. On the middle cross section of AARS, single-wing fractures, bi-wing fractures and multiple fractures are formed. Inside AARS, the main and branch fractures are formed. The synergy of TP, NBC and sleeves generates a complex fracture system composed of main fractures and branch ones, which reduces the influence of sand on fracture propagation. In short, properly weakening fracturing fluid infiltration by using NBC and sleeves, combined with a reasonable selection of TP concentration, have proved to be a productive way of improving hydraulic fracturing effect of tight sandstone. The findings contribute to a more comprehensive understanding of the initiation and propagation laws of hydraulic fractures of tight sandstone and conduce to the optimization of fracturing parameters. • We carried out temporary plugging agent fracturing experiments on artificial analogue rock samples of tight sandstone. • We monitored initiation and propagation of hydraulic fractures with acoustic emission system. • Temporary plugging agent concentration and fracturing fluid infiltration affects initiation and propagation of hydraulic fractures. • We put forward a productive way of improving hydraulic fracturing effect of tight sandstone.

An improved harmonic resonance mode analysis method for distribution power grid

Harmonic resonance endangers seriously safe and reliable operation of power grid and an appropriate resonance harmonic analysis method is of great importance. The traditional mode analysis method is a kind of main method to analyze harmonic resonance of power grid so to obtain various harmonic information such as resonance frequency, maximum excitation node and observation node as well as participation factor. However, its calculation efficiency is lower and has no way to judge accurately the maximum excitation node in the harmonic resonance of the distribution power grid. The improved mode analysis method proposed in this paper combines the frequency spectrum analysis with the traditional mode analysis method, and the condition of whether the harmonic resonance could occur at the determined excitation node at resonance frequency is added. Taking the distribution power grid in Bonan Oil area of Shengli Oilfield as an example, this paper analyzes the harmonic resonance of distribution network by using traditional mode analysis method and improved mode analysis method respectively. By comparing the analysis results of the two methods, the superiority of the improved mode analysis method is verified. The analysis of harmonic resonance of distribution network in Bonan Oil area shows that the improved mode analysis method proposed in this paper can accurately determine the harmonic resonance frequency and the highest excitation node of distribution network, while the traditional mode analysis method could not accurately judge the highest excitation node. In addition, the calculation time of the improved mode analysis method is only 17% of that of the traditional mode analysis method, which greatly improves the analysis efficiency.

Occurrence and fate of chlorinated methylsiloxanes in surrounding aqueous systems of Shengli oilfield, China

Mono-chlorinated products of cyclic volatile methylsiloxanes (cVMS), i.e., Monochlormet-hylheptamethylcyclotetrasiloxane [D3D(CH2Cl)], monochlormethylnonamethylcyclopenta-siloxane [D4D(CH2Cl)], and monochlormethylundemethylcyclohexasiloxane [D5D(CH2Cl)], were detected in water [<LOQ (Limit of quantitation) -86.3 ng/L, df (detection frequency) = 23%-38%, n=112] and sediment samples [<LOQ-504 ng/g dw (dry weight), df = 33%-38%, n=112] from 16 lakes located in Shengli oilfield of China, and had apparent increasing trends (31%-34% per annum) in sediments during Year 2014-2020. Simulated experiments showed that chloro-cVMS in sediment-water system had approximately 1.7-2.0 times slower elimination rates than parent cVMS. More specifically, compared with those of parent cVMS, volatilization (86-2558 days) and hydrolysis (135-549 days) half-lives of chloro-cVMS were respectively 1.3-2.0 and 1.8-2.1 times longer. In two species of freshwater mussels (n=1050) collected from six lakes, concentrations of chloro-cVMS ranged from 9.8-998 ng/g dw in Anodonta woodiana and 8.4-970 ng/g dw in Corbicula fluminea. Compared with parent cVMS, chloro-cVMS had 1.1-1.5 times larger biota-sediment accumulation factors (2.1-3.0) and 1.1-1.7 times longer half-lives (13-42 days). Their stronger persistence in sediment and bioaccumulation in freshwater mussels suggested that environmental emission, distribution and risks of chloro-cVMS deserve further attention.

Nonlinear Seepage Mathematical Model of Fractured Tight Stress Sensitive Reservoir and Its Application

A tight reservoir can only have industrial production value after fracturing. After volume fracturing, there are artificial fracturing zones and fracturing unmodified zones composed of a matrix, microfractures, and main fractures. There are also pressure-sensitive effects and nonlinear seepage in the matrix. There is an unsteady channeling flow between the matrix and microfractures and main fractures and a threshold pressure gradient in the matrix. The fluid flow between the three media and the transfer flow between the media are very complex. Aiming at the problem of poor simulation accuracy because the above characteristics of tight reservoir fracturing development are not considered in the current commercial numerical simulation software Eclipse, CMG, and VIP, the triple medium coupling nonlinear mathematical model of tight reservoir fracturing development matrix/microfractures/main fractures was established in this study, and the discrete mathematical model was constructed using the full implicit numerical solution method. The model considered the effects of threshold fracturing gradient and nonlinear seepage on the reverse side of seepage. In terms of pressure-sensitive effect, the latest generalized pressure-sensitive effect calculation model, considering rock physical parameters established by authors, was adopted. In terms of matrix/fracture transfer flow, the nonlinear matrix/fracture transfer flow model considering threshold pressure gradient and pressure-sensitive effect established by authors was adopted. Finally, a tight reservoir numerical simulation software was developed based on a triple medium coupling nonlinear model. The software was used to simulate the development effect of turbidite tight reservoir in Wang 587 Block of Jiyang depression, Shengli Oilfield. The results showed that the fitting accuracy of the new model was 13.3% higher than that of Eclipse, and the calculation results were more in line with the production practice of tight reservoirs. The new model established an important theoretical basis for scientifically and effectively guiding the development of tight reservoirs.

Surfactant–polymer binary oil-displacement agents suitable for multiple oilfield blocks

In oil-displacement processes, a compound surfactant system is used to reduce the crude oil–water interfacial tension (IFT) via the synergistic effect of multiple surfactants. To the best of our knowledge, however, since there is no systematic quantitative comparison tool for the intermolecular effects of surfactants, the synergistic mechanisms of surfactant systems have not been analyzed in depth. This paper proposes the use of intermolecular scission energy as a quantitative tool to analyze the synergistic mechanism of surfactants, mitigating the aforementioned issues. As a case study, this paper focuses on the Y-1, K-1, and K-2 blocks of Shengli Oilfield, China. Based on the intermolecular scission energies of the crude oil IFT-reducing agents of each block, along with the fact that they have the same composition, the co-surfactant amide betaine was added to a conventional alkanolamide–hydroxysultaine system to form a common surfactant system suitable for use in all three blocks. This new system achieved ultra-low IFTs—that is, ∼10−3 mN/m—for all three oils at a concentration of only 0.05%. The surfactant system can effectively reduce the oil–water IFT for 125 days under 90 °C formation conditions, with good thermal stability. After flowing in the formation for 30 days, the concentration of the system is still maintained at about 95%, and it is not easily adsorbed. In the visualization of the oil displacement test, the total oil recovery of a surfactant–polymer system (SP system)—composed of a surfactant system and a polymer—was found to be over 62%, an increase of more than 20%.

Recyclable surface-functionalized Fe3O4 particles for heavy oil viscosity reduction

The main objective of this study is to design and apply surface-functionalized Fe3O4 particles to reduce the viscosity of heavy oil from Shengli Oilfield and to study the mechanism of viscosity reduction. Fe3O4 particles were synthesized by the co-precipitation method and modified with 3-propyl trimethoxysilane (KH570), oleic acid (OA), and triethoxyvinylsilane (A151) to obtain Fe3O4–KH570, Fe3O4-OA, and Fe3O4-A151, respectively. The particles were characterized through Fourier Transform Infrared Spectroscopy (FTIR), Thermogravimetric Analysis (TGA), and Dynamic Light Scattering (DLS). The contact angle and dispersion stability in kerosene were evaluated. The average net degree of viscosity reduction (%DVR) of Fe3O4–KH570, Fe3O4-OA, and Fe3O4-A151 on Chenping heavy oil at 50 °C is 27.91%, 51.27%, and 29.44%, respectively. The surface functionalization of asphaltene aggregates, the improvement of lipophilicity, and dispersion stability after destruction are the main reasons for the decrease of heavy oil viscosity. Particle size and the ability to adsorb asphaltenes have no direct relationship with DVR. It was also confirmed that the modified Fe3O4 particles can effectively recycle from the oil under a magnetic field. This work developed a kind of recyclable Fe3O4 particles for heavy oil viscosity reduction, which was beneficial to lower the cost in heavy oil recovery.

The influence of international crude oil price on the crude oil spot price in China

With the proposal of the new development pattern of "dual circulation", the connection between China and the international market is even closer. As crude oil is one of the commodities which has been financialized deeply, the active international market involves millions of investors from the world. What kind of impact will the international crude oil price have on the crude oil price in China? Based on the spot price of Daqing oil field and Shengli oil field from January 2005 to March 2021, this paper uses quantile regression to empirically analyze the impact of international oil price on the oil spot price in China. Through the quantile regression, this paper finds different degrees of influence of international crude oil on China’s crude oil price.

Research on Evaluation Method of Ultralow Interfacial Tension Foam for High-Temperature and High-Salinity Reservoirs: A Field Case in Shengli Oilfield, China

Research on Evaluation Method of Ultralow Interfacial Tension Foam for High-Temperature and High-Salinity Reservoirs: A Field Case in Shengli Oilfield, China

Heavy oil development: Shengli Oilfield

Heavy oil development: Shengli Oilfield

Automatic Preidentification of Fault Structural Traps From Graph View

Fault Structural Traps (FSTs) are one of the main gathering places for oil and gas, so their identification on the structure map is of great importance and thus a fundamental work in exploration. In the society of exploration geophysics, such a work is accomplished by experienced experts manually, which motivates us to propose a more effective method to identify the traps automatically. From the graph view, we propose a workflow to realize the automatic pre-identification of FSTs preliminarily according to the subsurface faults distribution. The automatic pre-identification strategy includes three main components: fault information acquisition, traps coarse identification, and rock body correction. First, the fault information acquisition is a fundamental work to obtain the connectivities between faults. Second, in the traps coarse identification, an undirected graph (undigraph) model is established to digitally describe the relationship between faults. Meanwhile, the Alpha Shape (AS) algorithm and Depth First Search (DFS) algorithm are used to add auxiliary lines for connected subgraphs and find basic loops of the undigraph respectively. Finally, a correction algorithm is designed to find the traps formed by blocky rock bodies and their connected faults. The effectiveness of the FSTs pre-identification (i.e., annotating all potential FSTs on the structure map) method is verified by illustrative examples in the Shengli Oilfield, which are almost consistent with the expertise.

Study on technical measures to improve oil recovery during extra high water cut period

China’s petroleum resources are mainly continental facies with high petroleum density. Due to high heterogeneity, mining by traditional methods is not effective, and nearly half of the resources are not developed. The onshore oil fields that have been developed in Daqing area; Liaohe, Shengli and other large oil fields have entered high water cut stage, but there are still a lot of problems such as scattered remaining oil distribution, flooded reservoir, low recovery factor, reduced production and poor economic benefits. Based on this, this paper mainly analyzes the related technical measures to enhance oil recovery in the ultra-high water cut period.