Table of Content

25 December 2020, Volume 27 Issue 6

Previous Issue    Next Issue

Summary

Continuous Exploration and Discovery Technology and Its Application in Liaohe High Mature Exploration Area

Meng Weigong

2020, 27(6):  1-11.  DOI: 10.3969/j.issn.1006-6535.2020.06.001

Asbtract ( )   PDF (3383KB) ( )  

References | Related Articles | Metrics

After more than 50 years of exploration, Liaohe Exploration Area has entered the stage of high maturity exploration as a whole. How to obtain new exploration discoveries continuously in the Old Area is the primary problem to solve the contradiction of resource substitution. During the 13th Five-year Plan, based on the reconstruction of old data and by taking the building of a new oil-gas reservoir model as the core, the reconstruction of old data as the basis and the new technology of “wide azimuth, wide band, high density” as the means, we have carried out “overall understanding, overall evaluation and overall deployment” for each depression of Liaohe Exploration Area, found five exploration fields, namely conglomerate reservoir in steep slope zone, deep overpressure igneous reservoir, shale reservoir in the central depression, residual Mesozoic buried hill reservoir and middle and shallow complex fault block reservoir, and put one 100 million-tonnage reserve zone and eight 10 million-tonnage reserve zones in place. The exploration practice during the 13th Five-year Plan shows that there is still great potential for exploration in the old areas rich in oil and gas by freeing the minds, proceeding with confidence, breaking through theory and optimizing technology.

Development of Fire flooding Technology in Liaohe Oilfield

Zhang Fangli, Hu Changhao, Ma Hongbin, Shi Haitao, Zhang Hongbao

2020, 27(6):  12-19.  DOI: 10.3969/j.issn.1006-6535.2020.06.002

Asbtract ( )   PDF (1863KB) ( )  

References | Related Articles | Metrics

Heavy oil reservoirs in Liaohe Oilfield have the characteristics of deep burial depth and multiple oil types. In order to explore the effective replacement technology in the later stage of steam injection in heavy oil reservoirs, through indoor physical simulation and field tests, the feasibility of fire flooding after stem flooding was discussed in different types of reservoirs, such as middle to deep or extra deep layered reservoir, thick massive reservoir, water-flooded heavy oil reservoir, and shallow low-permeability heavy oil reservoir. A series of technologies aiming at different types of reservoirs was formed, which include reservoir description technology for fire flooding, indoor physical simulation technology, reservoir engineering design technology, oil production technology, development effect evaluation technology, etc. The recovery degree of the reservoirs after fire flooding had been greatly improved, effectively alleviating the decline in production. The paper discussed the exploration history of fire flooding technology in Liaohe Oilfield, and systematically summarized the supporting technologies of fire flooding for developing different types of oil reservoirs. The research results can provide a reference for the fire flooding development of Liaohe Oilfield and for the similar heavy oil reservoirs.

The Practice of Steam Assisted Gravity Drainage in Liaohe Oilfield

Wang Hongyuan, Yang Liqiang

2020, 27(6):  20-29.  DOI: 10.3969/j.issn.1006-6535.2020.06.003

Asbtract ( )   PDF (2168KB) ( )  

References | Related Articles | Metrics

Liaohe Oilfield is the largest thermal recovery base of heavy oil in China, which enjoys abundant heavy oil resources. Most of the heavy oil resources are productd by steam stimulation, with oil recovery factors of only 22%～25%. To improve the recovery factors of the superheavy oil reservoirs in Liaohe Oilfield, the laboratory physical simulation of steam assisted gravity drainage (SAGD) were carried out targeting the more deep buried depth of the reservoirs, interlayer developed reservoir, and increasing heterogeneity after steam stimulation. Meanwhile, a series of studies were conducted to tackle key issues inreservoir engineering, such as drilling and production technology and surface treatment technology. SAGD in Liaohe Oilfield experienced three stages,the pilot tests,the first phase of industrialized project and the enlargement of industrialization. And now there are 72 SAGD well groups and the annual oil production reached to 105×10⁴t/a in 2019, exceeded 100×10⁴t/a for three years. The SAGD technologies of reservoir geology, reservoir engineering and progress of surface technology were mature and complete, which provides references for the development of similar oil reservoirs.

Preliminary Discussion on Current Status and Development Direction of Heavy Oil Recovery Technologies

Jiang Qi, You Hongjuan, Pan Jingjun, Wang Zhongyuan, Gai Pingyuan, Ian Gates, Liu Jiali

2020, 27(6):  30-39.  DOI: 10.3969/j.issn.1006-6535.2020.06.004

Asbtract ( )   PDF (1510KB) ( )  

References | Related Articles | Metrics

Heavy oil reserves account for more than 2/3 of the discovered crude oil resources in the world. Due to the high viscosity and poor fluidity of heavy oil, its recovery is difficult, with high technical requirements. According to the characteristics of many types and large depth changes of heavy oil reservoirs in China, the current status of heavy oil recovery at home and abroad and the main technical direction of improving recovery efficiency were analyzed and summarized; combining with the field production performance, the adaptability, application potential and main technical challenges of existing commercial recovery technologies to different types of heavy oil reservoirs were discussed. The results show that steam huff and puff is still the main method of heavy oil recovery in China. However, most of the oil fields have entered the end period of production, and the recovery efficiency is low. At present, the application scope of mature replacement technologies (steam flooding, SAGD and in-situ combustion) is limited, so it is urgent to develop new replacement technologies. The series of heavy oil development technologies in the middle and deep layers are relatively mature, but the EOR technologies for deep, ultra-deep and complex types (such as fractured/karst cave) of heavy oil reservoirs are not yet mature. It is of more practical significance and application prospect to strengthen the research on frontier technologies such as generating steam downhole, solvent assisted, in-situ upgrading and gasification. The research results can be used for reference and guidance to expand the research field and direction of heavy oil recovery technologies.

Technologies and Practice of Water-flooding Development in Liaohe Oilfield

Wu Yi, Shi Lihua, Yin Yanfang, Qiu Lin

2020, 27(6):  40-46.  DOI: 10.3969/j.issn.1006-6535.2020.06.005

Asbtract ( )   PDF (1140KB) ( )  

References | Related Articles | Metrics

Water-flooding oil reservoirs in Liaohe Oilfield are characterized by more faults, multiple oil-bearing series, strong reservoir heterogeneity, high shale content and complex reservoir types. In the past 10 years of development practice, combined with the difficulties in water-flooding development of various oil reservoirs, 12 core development technologies have been developed, including deep fine reservoir description, subdividing water-flooding adjustment, identification of inefficient and ineffective water cycle, fine potential tapping by combination of secondary and tertiary recovery, and multivariate injection-production regulation and control, and a set of water-flooding development technologies suitable for medium-high permeability sandstone oil reservoir, low-permeability sandstone oil reservoir and special lithologic oil reservoir have been formed. The annual oil production of water-flooding oil reservoirs has increased from 324×10⁴t/a to 360×10⁴t/a, and the water-flooding recovery ratio has increased by 3.3 percentage points. The technical countermeasures to improve the effect of water-flooding development in old oilfields have certain guiding and reference significance for the same type of oil reservoirs.

Research and Application of Nano-materials to Enhance Oil and Gas Recovery Technology

Hou Jirui, Wen Yuchen, Qu Ming, Wu Wenming, Zhang Wei, Ding Yitong

2020, 27(6):  47-53.  DOI: 10.3969/j.issn.1006-6535.2020.06.006

Asbtract ( )   PDF (1284KB) ( )  

References | Related Articles | Metrics

Combined with the field application cases at home and abroad in the past 20 years, the classification and oil displacement mechanism of nano-materials were analyzed and discussed. the technical advantages and problems of nano-materials in enhanced oil recovery were analyzed. The key factors and development direction of nano-materials applied in the field of enhanced oil recovery in the future were discussed and prospected. At present, the nano-particles used in enhanced oil recovery can be divided into metal oxides, organic particles and inorganic particles. The oil displacement mechanism of nano-materials is usually a combination of various mechanisms. Lamellar nano-materials have unique advantages. Hereinto, the new 2D intelligent nano oil displacement technology has been successfully carried out in many field tests and has great application potential in the field of enhancing oil recovery.

Research progress and development direction of steam flooding technology for medium and deep heavy oil reservoirs

Hu Changhao

2020, 27(6):  54-59.  DOI: 10.3969/j.issn.1006-6535.2020.06.007

Asbtract ( )   PDF (1110KB) ( )  

References | Related Articles | Metrics

To further improve the recovery ratio of medium and deep heavy oil reservoirs, more than 30 years’ steam flooding course in Liaohe Oilfield is comprehensive review, we have systematically summarized the development course, development status and application effects of medium and deep heavy oil steam flooding theory and technology of Liaohe Oilfield were summariled systematically. The research shows that the medium and deep heavy oil steam flooding technology of Liaohe Oilfield has experienced four development stages, exploration, pilot test, large-scale implementation of Gade I oil reservoirs as well as testing and substitution of Gade II oil reservoirs; the theoretical understanding and development technology have experienced the direct application of mature technologies at home and abroad into the research and development innovation combined with the geological characteristics of Liaohe, forming a series of medium and deep heavy oil steam flooding development technologies centered on the theoretic understanding of oil displacement mechanism, reservoir engineering design technology and supporting efficient injection and production technology; currently, the depth limit of steam flooding has exceeded 1 600 m, and the viscosity of available heavy oil is increased to 200 000 mPa·s, and the estimated recovery ratio is 55%-65%, reaching the international development level of shallow steam flooding; and in the future, we should develop and break through the difficulties and key points in medium and deep steam flooding. This research provides an important support for the stable production of 10 million tons in Liaohe Oilfield.

Study on Fire Flooding Development Mode of Multi-layer Reservoirs

Guan Wenlong, Gong Yuning, Tang Junshi, Song Yang, Li Qiu

2020, 27(6):  60-66.  DOI: 10.3969/j.issn.1006-6535.2020.06.008

Asbtract ( )   PDF (1168KB) ( )  

References | Related Articles | Metrics

In the fire flooding development process of multi-layer reservoirs, in the early stage of ignition and combustion in the wellbore, there exists some problems such as low longitudinal effective producing degree of the reservoirs, and difficulty in tracking and controlling reservoir dynamics. In response to these problems, combined with indoor experimental data and field test data, by using reservoir engineering analysis methods, it was clarified that the essential feature of fire flooding is high temperature oxidation reaction, that the most critical parameter ensuring high temperature oxidation was the gas injection intensity at different stages, and that fire flooding development mode was a last mode for oil recovery. Applying the above research results to the design of a fire flooding development plan for a multi-layer reservoir, and the results show that the fire flooding development plan for multi-layer reservoirs should subdivide the development formation, that the total thickness of the target layer should be less than 30 m and the thickness of the oil-bearing sublayer should be less than 20 m, and that stable production can be achieved by layer-by-layer return and replacement from bottom to up. The research content is of great significance for the fire flooding development of multi-layer reservoirs to maximize the recovery rate and reduce engineering risks.

Re-understanding of Steam Flooding Mechanism and Research on Full Life Cycle Development

Li Xiangfang, Ma Hongbin, Yang Jian, Fu Yongjiang, Zheng Limin

2020, 27(6):  67-74.  DOI: 10.3969/j.issn.1006-6535.2020.06.009

Asbtract ( )   PDF (1559KB) ( )  

References | Related Articles | Metrics

In view of the high water content and the low heat utilization rate faced by the steam flooding development of Qi 40 Block in Liaohe Oilfield, a full life cycle evaluation method of steam flooding was proposed, and a design method of injection-production parameters for each flooding stage was established. The research results show that: based on the correlation between viscosity and temperature of heavy oil, the current "three fields" of steam flooding can be modified to "four fields", which can more intuitively evaluate the development effect of steam flooding. Based on the different mechanisms during the steam flooding process, the current "3 stages" of steam flooding was divided into "4 stages", which can more accurately evaluate the whole process of steam flooding.Combining the characteristics of viscosity field and heat utilization situations, design the injection-production parameters for each steam flooding stage: in the establishment stage of temperature field for heat connection and the steam displacement stage, the optimal steam injection intensity was 200 m³/(d·m·km²) and 150 m³/(d·m·km²), respectively; in the injection-production parameter adjustment stage when the steam broke through obviously, the optimal steam injection intensity was 120 m³/(d·m·km²), and the dryness was controlled at about 0.2, which was beneficial to the development effect of this stage. After the full steam channeling of steam flooding, the development mechanism of steam-hot water alternate injection and development mechanism of intermittent steam flooding were analyzed. The two development patterns were compared with continuous steam flooding, and the development effects indicated that steam-hot water alternate injection and intermittent steam flooding were the better freplacement methods after full steam channeling. The research results have certain guiding significance for the steam flooding development of Qi 40 block in Liaohe Oilfield, which can provide a reference for the development of similar heavy oil fields.

Geologic Exploration

Application of Prediction Technology for Favorable Tight Oil and Gas Areas in Jixi Basin with Low Exploration Degree

Zhao Rong, Wang Pengyan

2020, 27(6):  75-80.  DOI: 10.3969/j.issn.1006-6535.2020.06.010

Asbtract ( )   PDF (1374KB) ( )  

References | Related Articles | Metrics

In view of the problems such as lack of data and high difficulty in prediction of favorable tight oil and gas areas in basins with low exploration degree, through the analysis of oil and gas accumulation mechanism of typical tight oil and gas basins at home and abroad, the main controlling factors of hydrocarbon accumulation were studied, and the prediction theory and process of favorable tight oil and gas areas in basins with low exploration degree were formed, and relevant standards were proposed. The study shows that the formation and distribution of tight oil and gas are directly controlled by hydrocarbon generation, reservoir physical properties and structural stability. The criteria of favorable distribution areas for tight oil and gas are as follows: there are effective source rocks that have entered hydrocarbon generation threshold; the minimum value of hydrocarbon generation intensity is from 7×10⁸-10×10⁸m³/km² during geological history; the surface permeability of the reservoir adjacent to the source rock profile is less than 1.00 mD; the regional stratum dip angle is below 4 °; the faults are not developed. The Chengzihe Formation in the Jixi Basin has effective hydrocarbon generation ability, it has adjacent source and reservoir, and oil and gas have been found in tight sandstone reservoir, thus it has tight oil and gas exploration prospect. According to the comprehensive analysis of hydrocarbon generation, reservoir and structural background, the favorable areas for tight oil and gas are distributed near the depression area, with an area of 291.3 km². This method accords with the reservoir forming mechanism and has operability, thus it can provide reference for tight oil and gas exploration in similar basins with low exploration degree.

Prediction and Characterization Technology of Hydraulic Unit in Tight Reservoirs Based on Bayesian Inference

Yu Peng, Yang Fulin, Kegang Ling, Oyinkepreye David Orodu, Yang Xingye

2020, 27(6):  81-87.  DOI: 10.3969/j.issn.1006-6535.2020.06.011

Asbtract ( )   PDF (1732KB) ( )  

References | Related Articles | Metrics

Aiming at the problem of complex reservoir structure and difficult prediction in Xiaohaotu-Da16 well area, Bayesian mining algorithm and computer-aided simulation method were used to build the fine hydraulic unit model and correlate the development law of reservoir sand bodies in the target area. The results show that the characterization technology based on Bayesian inference can effectively identify the types of reservoir hydraulic units and provide accurate geological information for gas reservoir description. The exponential function increment method performs better in the process of well logging curve segmentation. The clustering rule of the samples in R_t logging interval is attributed to the high water-cut characteristics of the reservoir. The three types of hydraulic units have large original oil and gas reserves and potential, and they are also urgent to be broken through in EGR process. The research results provide reference for predicting favorable reservoir areas.

Lobate Shallow-Water Delta Reservoir Architecture Characterization in the Southern Bohai Sea

Jiang Yuanpeng, Zhang Lan, Wu Qiongyuan, Sun Guangyi, Wang Xijie

2020, 27(6):  88-95.  DOI: 10.3969/j.issn.1006-6535.2020.06.012

Asbtract ( )   PDF (4121KB) ( )  

References | Related Articles | Metrics

The Neogene shallow water delta reservoirs of the Minghuazhen Formation in the southern Bohai Sea show a wide lobate distribution. The complex reservoir genesis and architecture and relatively low conventional reservoir characterization accuracy based on composite sandbody limit the understanding of remaining oil distribution and recovery in the middle-late development stage. The Sandbody 1167 of BZ28 Oilfield in the southern Bohai Sea was taken to separate the configuration unit based on the modern sedimentary evolution mode of shallow water delta. High-resolution seismic attribute, logging facies, horizontal well geo-steering, production history and other data were comprehensively used to separate the sandbody configuration step by step from the sedimentary lobes in composite river channel, distributary channel and distributary bar. Research indicates that the lateral shallow water delta reservoir in the study area shows a alternate distribution of distributary channel and distributary bar. The reservoir sedimentation is dominated by distributary bar, which is composed of vertical stacking between sedimentary lobe, low angle frontal accumulation and backflow degeneration. The distributary channel is a water channel with relatively small reservoir thickness. This research could provide certain guidance for the understanding of water flooding in the production.

High-precision Prediction of Thin Sandstones in Dujiatai Oil Layer of Shuguang Area

Chen Chang, Jin Ke, Lei Wenwen, Wang Heng, Guo Feng, Qian Lixin, Qin Xichun

2020, 27(6):  96-101.  DOI: 10.3969/j.issn.1006-6535.2020.06.013

Asbtract ( )   PDF (2638KB) ( )  

References | Related Articles | Metrics

In order to solve the problem that it is difficult to predict the thin sandstones in the fan delta front facies of Dujiatai oil layer of Shuguang Area, the high-precision prediction of thin sandstones was carried out by using seismic waveform indication simulation technology. The results show that the accuracy of identifying thin sandstones by self-potential (SP) from seismic waveform indication simulations can reach 3.0-8.0 m and the inversion coincidence rate can reach 81.5%; the distribution characteristics of thin sandstones in the fan delta front facies of the Du 2 Member in Shuguang Area are clarified. Three thin sandstone development areas of fan delta front mouth bar and sheet sand microfacies (Du 130-Du 144, Du 300-Shu 100, Shu 66-Shugu 19-Shu 175 well areas) are identified, with a total area of 26.0 km². The research results have guided the deployment of two exploration wells, both obtaining industrial oil and gas flow, which laid the foundation for further improvement of reserves and productivity in Shuguang Area. The seismic waveform indication simulation technology is of great significance for thin sandstone prediction and lithologic reservoir exploration in Shuguang Area.

Classification and Identification of Karst Palaeogeomorphology and Prediction of Favorable Areas in Southern Yan'an Gas Field, Ordos Basin

Zhou Yucheng, Yao Guangming, Wei Hehua, Quan Lianshun, Gao Fei, Zhao Meiye, Liu Peng

2020, 27(6):  102-107.  DOI: 10.3969/j.issn.1006-6535.2020.06.014

Asbtract ( )   PDF (5296KB) ( )  

References | Related Articles | Metrics

The research degree of paleogeomorphology in the southern Yan'an gas field is poor, which is difficult to meet the requirements of fine exploration. By comprehensive utilization of drilling, well logging, mud logging and 2D seismic data, the karst palaeo-geomorphology of weathering crust on the top of Lower Paleozoic Ordovician in the southern Yan'an gas field was finely restored. Combined with the results of drilling and gas testing, the control effect of karst palaeo-geomorphology on gas reservoir distribution was clarified, and favorable target areas were divided. The results show that: (1) The study area can be divided into three secondary palaeo-geomorphological units: the western karst platform, the central karst slope and the eastern karst basin, and the third-order palaeo-geomorphic units were further identified on the secondary palaeo-geomorphic units; (2) The two flanks of grooves and the transition area between highland and depression have strong karstification and better reservoir physical properties, which are the most favorable target areas; (3) The physical properties of groove, depression and there locations far away from groove are worse. Specifically, some areas of Wuqi County and Zhidan County, Ganquan County, and the western Fuxian County and Huangling County in southwest were selected as favorable karst reservoir areas. This study can effectively improve the success rate of drilling and provide strong support for increasing reserves and production in the later stage of gas fields.

Study on Low-Resistivity Characteristics and Genetic Mechanism of Putaohua Oil Layers in Songliao Basin

Xiao Shengdong

2020, 27(6):  108-113.  DOI: 10.3969/j.issn.1006-6535.2020.06.015

Asbtract ( )   PDF (1659KB) ( )  

References | Related Articles | Metrics

The Putaohua oil layers in the Songliao Basin are widely developed with low resistivity and has broad development prospects. However, their genesis is affected by many factors, their mechanism is complex, and they are difficult to be identified. Hence, it is hard to distinguish oil layer from water layer only from conventional well logging, which greatly limits the tapping potential of this kind of oil layer. In view of this difficulty, starting from the analysis of the characteristics of low-resistivity oil layers, the genetic mechanism of the low-resistivity oil layers was analyzed from 7 external and internal factors. The results show that sedimentary facies belt and clay mineral type, content and distribution form are the main controlling factors for the development of low-resistivity oil layers in this area. Structure and pore texcture, and interbedding sandstone and mudstone also have certain influence on the development of low-resistivity oil layers in this area, while mud invasion and salinity of oil-water layers have little influence on them. The research results have achieved good application results in the field practice of low-resistivity oil layer identification, which provides a more reliable geological basis for the evaluation and identification of this type of oil layers and the prediction of potential areas, and has important practical significance for increasing reserves and production in this area.

Reservoir Engineering

Comprehensive Evaluation on Operation and Research on Capacity Expansion Potential of Shuang 6 Gas Storage

Li Xiaoguang, Hu Changhao, Min Zhongshun, Sheng Cong, Liu Jie, Li Bin

2020, 27(6):  114-119.  DOI: 10.3969/j.issn.1006-6535.2020.06.016

Asbtract ( )   PDF (1799KB) ( )  

References | Related Articles | Metrics

Since put into operation in 2014, the Shuang 6 gas storage in Liaohe Oilfield has experienced smooth and efficient operation of "six injections and four productions". In 2018, the Shuang 6 gas storage took the lead in achieving capacity summit and expansion among CNPC's major gas storages, and at the end of the sixth gas injection period, the inventory reached 53.27×10⁸m³, with capacity reaching rate of 129%. In view of the unclear direction of the future expansion of the gas storage, starting from the geological characteristics and dynamic production analysis of the gas reservoir, comprehensively using the dynamic and static data as well as the monitoring data from observation wells, combined with numerical simulation technology, the injection-production status, pressure changes, gas-liquid interface changes, and trap sealing performance of the gas reservoir were studied, and on this basis, the potential for capacity expansion and peak shaving was evaluated. The research results show that the injection-production capacity of gas storage is getting better year by year, and the adopted vertical-horizontal well pattern has greatly improved the operation efficiency. During the process of repeated injection and production, the production of crude oil and migration of edge water are the main reasons for capacity expansion of the gas reservoir. Based on the dynamic production analysis, combined with geological characteristics of the block, 15 injection and production wells would be newly deployed. It was expected that after the implementation of the new wells, the control degree of the storage capacity could be increased to more than 95%.The research results provide a basis for on-site production management as well as capacity expansion and peak shaving, which has certain guiding significance for the construction of the same gas storages.

Numerical Simulation Research on Microwave In-situ Heating Technology for Developing Heavy Oil in Low-permeability Reservoirs

Li Xiaogang, Zhu Jingyi, Yang Zhaozhong, Xie Shiyi, Jia Min

2020, 27(6):  120-126.  DOI: 10.3969/j.issn.1006-6535.2020.06.017

Asbtract ( )   PDF (1891KB) ( )  

References | Related Articles | Metrics

In the exploitation of low-permeability heavy oil reservoirs, aiming at the problems such as low reservoir injection capacity, high heat loss, and large water consumption, etc., numerical simulation technique was used to study the microwave heating technology for developing heavy oil. Through establishing multiple physical field models such as electromagnetic field model, heat transfer field model, and flow field model, the heavy oil viscosity reduction effect and heat transfer mechanism of microwave radiation was clarified. The research results show that after microwave heating, heavy oil reservoirs can be divided into three zones, namely electromagnetic penetration zone, conduction zone in porous media and unheated zone; the best radiation frequency is 2 450 MHz, and increasing power can quickly increase the formation temperature; in order to avoid overheating around the wellbore, a stepped heating mode with gradual power reduction should be adopted; hydraulic fractures can effectively improve the seepage channels of low-permeability reservoirs, and it can be used in conjunction with microwave heating to develop heavy oil reservoirs. This research can provide a reference for developing low-permeability and high-viscosity heavy oil.

Experimental Research on Microbial Flooding Technology for Enhancing Oil Recovery in High-pour-point Reservoirs

Wen Jing, Xiao Chuanmin, Guo Fei, Wang Kuibin, Ma Jing

2020, 27(6):  127-132.  DOI: 10.3969/j.issn.1006-6535.2020.06.018

Asbtract ( )   PDF (1634KB) ( )  

References | Related Articles | Metrics

High pour point oil has the characteristics of high freezing point, high wax content, and high wax precipitation temperature. These characteristics may cause cold damage to the near-well zone, reduce reservoir permeability, and affect seepage law, furthermore, they restrict the effect of recovery enhancing technology like water flooding altering to chemical flooding. In response to these problems, through laboratory experiments the endogenous microorganisms in the formation fluid of Shen84-An12 Block were separated and identified, two high-temperature resistant microbial strains were extracted, the underground activation system of the strains was optimized, and the mechanism of microbial flooding of high pour point oil reservoirs was explored. The experimental results show that the microbial flooding system has the effect of degrading the waxy components of high-pour-point oil. The microbial flooding system can effectively reduce the long-chain saturated hydrocarbons above C₂₀, with degradation rate ranging from 19% to 33%. After the improvement, the freezing point of crude oil was reduced by 2 to 6 ℃, and the recovery rate was 9 percentage points higher than water flooding. This research can provide a reference for solving cold damage in high-pour-point oil reservoirs, improving oilfield development effects, and enhancing development effects.

Study on Viscosity Reduction Mechanism and Oil Displacement Effect of Heavy Oil Activator

Wang Xudong, Zhang Jian, Shi Leiting, Zhao Juan, Yang Guang, Liang Xuwei

2020, 27(6):  133-138.  DOI: 10.3969/j.issn.1006-6535.2020.06.019

Asbtract ( )   PDF (1344KB) ( )  

References | Related Articles | Metrics

Viscosity reduction and cold production of heavy oil is the main method for offshore oilfield development. In order to deeply understand the viscosity reduction mechanism and application effect of heavy oil activator in heavy oil reservoirs with crude oil viscosity ranging from 150 mPa·s to 1 000 mPa·s, by means of indoor physical simulation experiment and dissipative particle dynamics simulation technology, the viscosity reduction mechanism and displacement effect of the activator on heavy oil was studied. The results show that the heavy oil activator can increase the viscosity of the water phase, reduce the oil-water interfacial tension, and can effectively reduce the viscosity of the conventional flowable heavy oil. The research results on the molecular scale show that the molecule of heavy oil activator has a significant inhibitory-dispersing effect on asphaltene aggregates. The active groups in the activator molecule can increase the interlayer spacing and chain spacing of the aromatic hydrocarbon in asphaltene, reduce the asphaltene aggregation height and layers, weaken the interaction among asphaltenes, destroy the aggregation structure of the heavy components in heavy oil, and disperse the heavy oil, thereby enhancing the fluidity of crude oil. Whether in indoor core displacement experiments or in field applications, the synergistic effects of multiple mechanisms of heavy oil activators can achieve good water decrease and oil enhancement effects. From the molecular level, the study clarified the viscosity reduction mechanism of heavy oil activator, which can provide a theoretical guidance for the field application of heavy oil activator.

Research and Test of Chemical Flooding Technology in Unconsolidated Sandstone Reservoirs

Xu Guomin, Gao Zhongmin

2020, 27(6):  139-144.  DOI: 10.3969/j.issn.1006-6535.2020.06.020

Asbtract ( )   PDF (1349KB) ( )  

References | Related Articles | Metrics

The Shusan block of Shuguang Oilfield is an unconsolidated sandstone reservoir with a burial depth of 950 m and a shale content of 13.9%. Affected by this, the compaction of the reservoir is poor and the cementation of the reservoir is loose. The sand production of oil wells in the reservoir is serious, with poor development effects, and the predicted recovery rate is only 30.8%. The unconsolidated sandstone reservoir in Shu 3 block has entered into themiddle and later development stages, which has encountered a series of problems such as rapid water rise and poor development effects. After carrying out the research on chemical flooding related to reservoir engineering, the results show that the optimized formula system for chemical flooding and the ancillary sand control technologies can effectively improve oil recovery. Applying the research results to 6 well groups, after the pilot test of chemical flooding, the daily oil production was significantly increased, and the comprehensive water cut decreased by 14.2 percentage points, which effectively improved the development effect. The research provides a reference for the chemical flooding development of similar reservoirs.

Drilling & Production Engineering

Application Effect Evaluation of Cold Cracking Technology with High Energy Nanowave for Heavy Oil

Lu Shilin, Zhang Chengbo

2020, 27(6):  145-151.  DOI: 10.3969/j.issn.1006-6535.2020.06.021

Asbtract ( )   PDF (2087KB) ( )  

References | Related Articles | Metrics

In the process of lifting heavy oil in the wellbore as well as gathering and transporting on the ground, it is necessary to equip the viscosity reduction technologies such as thin oil mixing technology in the annulus, electric heating technology of hollow rods, and heating technology of gas furnaces, which leads to high production costs of heavy oil. According to the current status of new viscosity reduction technologies for heavy oil at home and abroad, after multiple field tests and analysis of cold cracking technology with high energy nanowave for heavy oil, it is confirmed that the technology has a significant effect on upgrading and visbreaking for heavy oil. After circulating treatment of crude oil with the technology, the maximum viscosity reduction rate was 81.7%, the maximum viscosity reduction rate of single treatment is 43.7%, the initial boiling point is reduced from 105 ℃ to 81 ℃, and the total fraction content was increased by 5.7% within 330 ℃, which can convert the heavy components into light components in the crude oil. The technology has a great reference significance for cost reduction and efficiency enhancement of heavy oil reservoirs.

Research and Practice of Composite Sand Control Technology for Extra-heavy Oil in Deep Reservoirs

Lang Chengshan

2020, 27(6):  152-157.  DOI: 10.3969/j.issn.1006-6535.2020.06.022

Asbtract ( )   PDF (1124KB) ( )  

References | Related Articles | Metrics

The marginal reserves of Wa 38 block in Liaohe Oilfield are difficult to exploit, and they are featured by large buried depth, long well section, multiple layers, thin layers, and high shale content. The serious sand production in these oil reservoirs has led to frequent sand sticking and pump inspections in oil wells, and the inefficient use of reserves has become increasingly serious. For this reason, a composite sand control technology idea offracturing sand control + screen sand control was put forward, forming series technologies such as resin coated sand, high-viscosity sand-carrying liquid system, sintered strainer screen, and high-sand ratio filling. The sand control efficiency has increased from 35% to more than 90%, the problem of serious sand production in the block has been solved completely, and the development effect has been improved dramatically. This technology realizes the overall efficient use of extra-heavy oil reservoirs as well as reasonable and economic development of the oilfield. This technology technically broadens the application limits of high-pressure squeeze-injection sand control technology, which can provide a technical reference for the development of similar reservoirs.

Study on the Supplement Timing of Leakage Stoppage Materials while Drilling for Deep Fractured Tight Reservoirs

Zhang Dujie, Jin Junbin, Chen Yu, Kang Yili

2020, 27(6):  158-164.  DOI: 10.3969/j.issn.1006-6535.2020.06.023

Asbtract ( )   PDF (1223KB) ( )  

References | Related Articles | Metrics

Deep fractured tight reservoirs have complex geological conditions and develops natural fractures, with high leakage risk of drilling fluid. In deep fractured tight reservoirs, adding leakage stoppage materials while drilling is an important means to prevent drilling fluid leakage and to control formation damage. In order to systematically study the timing to supplement the leakage stoppage materials consumed during the drilling process, a deep fractured tight gas reservoir in the Tarim Basin was taken as the research object. In the research, the pressure-bearing capacity of the oil-based drilling fluid system under different consumption ratios of the leakage stoppage materials while drilling was evaluated through experiments, and a calculation model for the consumption rate of the leakage stoppage materials while drilling was constructed based on the occurrence of formation fractures. The results show that when the material consumption rate exceeds 15%, the stoppage ability of the oil-based drilling fluid system while drilling is significantly reduced; the width and dip of the formation fractures have a significant impact on the consumption rate of leakage stoppage materials while drilling; the closer of the fractures to 90 °, the wider the fractures and the denser the fracture line, the faster the material consumption rate; after determining the supplement timing and supplement amount of the leakage stoppage materials while drilling, the changes in fracture width and dip should be paid special attention. This calculation model has achieved good application results in field tests, and has a guiding significance for efficient drilling in deep fractured tight reservoirs.