Lithologic Reservoirs

The volume fracturing for horizontal well is the key technology for effective exploitation of low permeability tight reservoir. The significant progress has been made in the area of deep and ultra-deep carbonate reservoir,tight sandstone and shale reservoir etc. The research work on description of fracture initiation and propagation, optimization of fracture parameters, optimization of perforation parameters, multi-scales fracturing optimization,staged fracturing tool,low damage fracturing and acid fluids system, synchronous gel breaking and flow back optimizing and fracture monitoring and diagnosing have been carried out. The formation stimulation technical chain with proprietary intellectual property rights has been established,including comprehensive assessment of formation,numerical reservoir simulation,optimum design method of hydraulic fracturing,efficient fracturing and acid fluids system,staged fracturing tool and fracture monitoring and diagnosing and flow back control etc. The latest progress of horizontal well fracturing technic and field applications in SINOPEC were summarized, which have been tested and generalized in tight sandstone gas reservoir in Ordos in North China, ultra-deep reservoir in Tahe Xinjiang and deep shale gas reservoir in Sichuan Basin. The effective stimulation reservoir volume and enhanced production of the low permeability reservoir above were significantly improved. These latest technics are important reference and guidance for the formation stimulation and enhancement work of similar domestic reservoirs.

Pore throat structure characteristics of Chang 3₁ reservoir in HuachiHeshui area, Ordos Basin

LIAO Mingguang, GUO Yunfei, YAO Jingli, LIAO Jijia, NAN Junxiang

2018, Vol.30(3): 17–26 Abstract ( 355 ) PDF (26736 KB) ( 474 )

doi: https://doi.org/10.12108/yxyqc.20180303

The Chang 31 low permeability sandstone reservoir in Huachi-Heshui area of Ordos Basin suffers low efficiency in water injection development, which results from the poor formation physical properties and complex pore throat structure. In order to formulate a reasonable development scheme,the pore throat characteristics were investigated by high pressure mercury injection and rate-controlled mercury injection technique. Microscopic identification and scanning electron microscope analysis were also conducted to discuss the genesis of microscopic pore throat structure. The results of high pressure mercury injection experiment show that reservoir porosity development could be classified into three types, including superior one,moderate one and poor one. According to the constant-rate mercury injection experiment,the reservoirs could be classified into typeⅠ large pore and midfine throat, type Ⅱ large pore and fine throat,and type Ⅲ large pore and tiny throat. Regarding the formations with different pore-throats structures,the pore characteristics are similar but the throat characteristics are evidently different. The reservoir physical properties are influenced by effective pore volume per unit volume and throat parameters. Porosity is mainly influenced by effective pore volume per unit volume, effective throat volume per unit volume and number of effective throats per unit volume. Permeability is mainly influenced by effective pore volume per unit volume and the radius of the throat. The pore throat ratio of typeⅠ,typeⅡ and typeⅢ reservoirs increase successively and the pore throat configuration relationship deteriorates successively. The pore throat ratio is negatively correlated with the permeability. The micropore throat structure is controlled by cementation and dissolution. The weaker cementation resulted in stronger dissolution and better micropore throats structure.

High efficient reservoir accumulation models of natural gas of Xujiahe Formation in northeastern Sichuan Basin

WANG Wei

2018, Vol.30(3): 27–34 Abstract ( 408 ) PDF (1717 KB) ( 131 )

doi: https://doi.org/10.12108/yxyqc.20180304

In order to figure out the differences of gas accumulation among different areas,deepen the study of the mechanisms of tight sand gas accumulation of Xujiahe Formation in northeastern Sichuan Basin, and find enrichment and high production zone of natural gas,the reservoir accumulation model and characteristics of Xujiahe Formation in northeast Sichuan Basin were studied in the aspects of source rock,gas source, structure, and sourcereservoir assemblage. The result shows that controlled by different types of source-reservoir assemblage and different tectonic deformation degree of local structure belts,there exists three types of high efficient reservoir accumulation models in Xujiahe Formation:coexisting source and reservoir model in continental weak deformation zone,near source accumulation and fault-sand pathway model in continental strong deformation zone,and doublesource supply and 3D network pathway model in continental-marine strong deformation zone. Based on these three accumulation models,the third member of Xujiahe Formation in western Yuanba area,the fourth member of Xujiahe Formation in central Yuanba area and the second member of Xujiahe Formation in Malubei area are the favorable target zones for the high efficient exploration and development in northeastern Sichuan Basin.

Quantitative evaluation on micro-heterogeneity of glutenite reservoir: a case from Kunbei Oilfield in Qiadam Basin

ZANG Shibin, ZHENG Yongxian, CUI Jun, MAO Jianying, ZHANG Xiaobo

2018, Vol.30(3): 35–42 Abstract ( 379 ) PDF (4056 KB) ( 197 )

doi: https://doi.org/10.12108/yxyqc.20180305

Different from the mono-pore media of routine sandstone reservoirs, glutenite reservoirs have the characteristics of dual-porosity media. Lager pores and smaller pores exist in glutenite reservoir simultaneously,as a result,the pore structure is complex and the micro-heterogeneity is strong. Lulehe Formation of Kunbei Oilfield in Qaidam Basin belongs to a glutenite reservoir. The capillary pressure curves have no horizontal parts,and pores distributions are obviously bimodal. The glutenite reservoir pore space of Kunbei Oilfield can be generally divided into two pore systems,one is the larger pore system which constitutes the preferred flowing paths and contributes 95% of flowing potentiality,and another the smaller one which constitutes non-preferred flowing paths and contributes 5% of flowing potentiality only. A parameter of main flowing space percentage obtained form the data of capillary pressure is precisely to describe the proportion of lager pores to the smaller ones of reservoir pore space, and then be used to evaluate quantitatively the micro-heterogeneity of glutenite reservoir. The results indicate that the average of main flowing space percentage in Kunbei Oilfield is 33%,that is,the larger pores take up smaller parts of reservoir pore space (about 1/3)but contribute greater permeability of the reservior,and the smaller pores take up most reservoir pore space (about 2/3)but contribute lesser flowing potentiality. The microheterogeneity of glutenite reservoir in Kunbei Oilfiled is severe.

Influences of soluble organic matter on reservoir properties of shale

CAO Taotao, DENG Mo, LIU Hu, SONG Zhiguang, CAO Qinggu, HUANG Yanran

2018, Vol.30(3): 43–51 Abstract ( 317 ) PDF (6493 KB) ( 115 )

doi: https://doi.org/10.12108/yxyqc.20180306

Soluble organic matter is an important part of organic matter. In order to study the effect of soluble organic matter on shale reservoir properties, the shales of Longmaxi Formation and Dalong Formation in northeastern Sichuan Basin were analyzed in the aspects of TOC content, rock pyrolysis, scanning electronic microscope, scanning electron microscopy combined with argon ion polishing, and the extraction of soluble organic matter and low-pressure N2 and methane adsorption experiments were carried out. The results show that: (1)Soluble organic matters are mainly existing in the surface and meso-macropore of kerogen, clay minerals and framboid pyrites in shales, especially low-maturity shales. (2)The specific surface area and methane adsorption capacity of extracted shale samples increased obviously compared with raw shale samples from Dalong Formation,while there are no obvious changes of specific surface area and methane adsorption capacity between the extracted shale samples and raw shale samples from Longmaxi Formation, indicating that the soluble organic matters in low-maturity shales could hinder the connectivity of pores and decrease methane adsorption capacity,but it has no obvious effect of soluble organic matter on high-maturity shales due to a low content of soluble matter in these shales. (3)Soluble organic matter content has a significant negative correlation with fractal dimension for Dalong shales,but has a positive correction for Longmaxi shales, indicating that soluble organic matter has an opposite effect on the pore heterogeneity for these two sets of shales with different maturities. (4)After extracting the soluble organic matter, fractal dimension values has a decreasing phenomenon for both extracted Dalong and Longmaxi shales, suggesting that the connectivity and uniformity of the pores are improved due to removing the soluble organic matter existing in shale pores. Therefore, through this study, soluble organic matter is deemed to an important factor of reservoir properties of shale,and it should be taken into consideration when characterizing the physical properties of the low-maturity shales.

Filling mechanism and potential tapping direction of Ordovician karst reservoirs in block-12 of Tahe Oilfield

TIAN Liang, LI Jialing, JIAO Baolei

2018, Vol.30(3): 52–60 Abstract ( 301 ) PDF (33061 KB) ( 147 )

doi: https://doi.org/10.12108/yxyqc.20180307

Karst caves are widely developed in Ordovician reservoirs in block-12 of Tahe Oilfield,but affected by filling of the underground river sediments and later denudation,the filled cave drilling rate of Upper Ordovician in denuded area is as high as 33%, which brings great difficulties such as well completion selection and completion method requirements. In order to improve the prediction level of filling cave,deepen the understanding of filling mechanism and clear the potential tapping direction of filling cave,based on drilling and logging data of 36 drilled wells,the filling caves were studied by using the methods of karst geology,seismic attributes,seismic reflection features and ancient landform restoration. The results show that the Ordovician in block-12 developed four types of karst cave filling, including underground river sediment, river lateral stacking, unconfined and collapse. The karst cave fillings can be divided into four types:siltstone,mudstone,collapse breccia and calcite. At the same time, three geophysical prediction methods for filling karst cave were established:seismic reflection contrast method,Middle and Lower Ordovician top surface shape comparison method and ancient landform restoration method. Three potential tapping directions were pointed out:intraformational potential, interlamination potential and interwell potential.

Characteristics and controlling factors of glutenite reservoir of Cretaceous Xiagou Formation in Ya' erxia area, Jiuquan Basin

YUAN Bochao, XIAO Wenhua, WEI Haoyuan, ZHANG Nan, DENG Yilin, ZHANG Guangwei

2018, Vol.30(3): 61–70 Abstract ( 367 ) PDF (40070 KB) ( 261 )

doi: https://doi.org/10.12108/yxyqc.20180308

In order to study the characteristics of glutenite reservoir, the data of core, casting thin sections, cathodoluminescence, scanning electron microscope and reservoir properties of glutenite of Cretaceous Xiagou Formation (K1g) in Ya' erxia area were studied to discuss the macroscopic and microscopic reservoir characteristics and influencing factors of clastic rocks. The results show that the K1g reservoir rocks are mainly composed of feldspathic lithic sandstone and lithic sandstone, and the fillings are mainly dolomites, with low texture and composition maturity. The pores are dominated by intergranular dissolved pores, intragranular dissolved pores, primary intergranular pores and super-macro pores,together with fine throat. The average porosity and permeability of the glutenite reservoir are 7.68% and 4.92 mD, respectively, showing the characteristics of low porosity and low permeability. The reservoir properties are controlled by sedimentation, diagenesis and tectonism. The favorable rock types are fine sandstone and pebbled sandstone, and the favorable sedimentary microfacies are mainly subaqueous distributary channel and mouth bar in fan delta front. Compaction and cementation make the reservoir properties poor, and dissolution of feldspar and carbonate and tectonism improves the reservoir properties. The study results can provide geologic basis for oil and gas exploration in this area.

Depositional models of barrier shoreline sedimentary system under guidance of source-to-sink system theory: a case from Daotang river in Qinghai Lake

CHEN Ji, JIANG Zaixing, LIU Chao, XU Wenmao

2018, Vol.30(3): 71–79 Abstract ( 460 ) PDF (23942 KB) ( 291 )

doi: https://doi.org/10.12108/yxyqc.20180309

The research of barrier shoreline sedimentary system of lakes usually plays a weak point of lacustrine sedimentology. Taking Daotang river in Qinghai Lake as an example,based on the outcrop,remote sensing data and"source-to-sink"method,it is defined that the"source-to-sink"system is composed of source area,alluvial fan,Daotang river,delta and barrier shore. Along with the uplifting of the Riyue Mountain and the Yeniu Mountain,the Daotang river basin was gradually transformed into a relatively closed"inland lake". With the warm dry climate and the further uplift of Yeniu Mountain,Daotang river overturned and formed a barrier-coastal sedimentary system. The formation of the sedimentary system is controlled by tectonic geomorphology,source of the material,climate change,river system and lake level variation. The researches about ancient provenance lithology of sedimentary basins,the lake palaeogeomorphology controlled by tectonic action and palaeowind field are favorable for predicting the sand in the continental rift basin.

Genetic types, configurations and distribution of sand bodies of Shanxi Formation in northeastern Ordos Basin

WANG Yue, GUO Yanru, ZHANG Yanling, LIU Junbang, TIAN Mingwei

2018, Vol.30(3): 80–91 Abstract ( 441 ) PDF (3223 KB) ( 257 )

doi: https://doi.org/10.12108/yxyqc.20180310

During the sedimentary period of Shanxi Formation in Ordos Basin,terrestrial plants flourished, which provides sufficient gas source for the formation of natural gas. The accumulation of oil and gas is controlled by lithology and lithofacies. Therefore,it is necessary to study the configuration and distribution of sand bodies of Shanxi Formation. In order to speed up the exploration of natural gas,guided by the basic principles of sequence stratigraphy and sedimentology,through comprehensive analysis of outcrop section,drilling and well logging data,the configuration and distribution characteristics of different genetic types of sand bodies under the fourth-order sequence framework of Shanxi Formation were emphatically studied. The result shows that the Shanxi Formation in the study area can be divided into five fourth-order sequences. The sand bodies are dominated by distributary channel sand bodies of braided-delta plain and the underwater distributary channel sand bodies of braided-delta front. The plane distribution of channel sand bodies is characterized by north-south zonation and east-west penetration. The superimposed modes of sand bodies are mainly three types:vertical overlap,vertical tangency and independent type. The fourth-order sequences including PSQ31 (equal to the Shan 23 section and the lower part of the Shan 22 section),PSQ32 (equal to the upper part of the Shan 22 section)and PSQ4 (1 equal to the Shan 12 section)are the main layers of natural gas exploration. Dabaodang, Yuxing Zhuang, Longzhen were selected as favorable exploration areas. The method and results could provide reference for the sequence stratigraphic division, sand body distribution law research and favorable zone optimization for the study area and similar areas.

Establishment of standard adsorption isotherms for shale reservoirs: a case of Chang 7 shale reservoir in Ordos Basin

HE Yanqing, ZHENG Li, YAN Changhui, TIAN Yuanyuan, WU Tingting, ZHAO Kele

2018, Vol.30(3): 92–99 Abstract ( 240 ) PDF (3388 KB) ( 254 )

doi: https://doi.org/10.12108/yxyqc.20180311

The composition of shale is complicated and the pore structure is diverse,which results in great difference in adsorption properties of shale. The adsorption isotherm curves of different rock samples in the same reservoir vary greatly. Thus,we need to establish a standard adsorption isotherm curves for shale. The adsorption isothermal experiments of shale samples from Chang 7 reservoir in Ordos Basin were carried out by low temperature liquid nitrogen method. The experimental curves were initially standardized and then classified according to the C value of the BET theory,taking the exponent of 2 as the standardized value. Then,the standard adsorption isothermal curve of all samples was used to fit the parameters of the four adsorption layer thickness equations in Matlab numerical analysis software to verify the adsorption isothermal curve. The fitting accuracy of the four adsorption layer thickness equations is:Carbon Black,square < Carbon Black,cube < Halsey < De Bore. Finally,the standard adsorption isothermal curves of each type of shale were obtained by parameter averaging. The standard of adsorption isothermal curve of shale reservoir,which stand a series of adsorption characteristics of reservoirs with similar surface properties,can be calculated directly in reservoir simulation and reservoir engineering use, reduce the data uncertainly caused by random selection of rock samples,simplify a lot of calculation process, and make the calculation result is representative.

Seismic response characteristics and quantitative prediction of high quality reservoirs in Jinzhou 25-1 oilfield

WANG Wei, WU Kui, HE Jing, ZHANG Jinhui, SHEN Hongtao

2018, Vol.30(3): 100–111 Abstract ( 334 ) PDF (44082 KB) ( 270 )

doi: https://doi.org/10.12108/yxyqc.20180312

To find high-quality reservoirs is the key for oil and gas exploration in main oil-bearing strata of the second member of Shahejie Formation in Jinzhou 25-1 oilfield and its surrounding areas in northern Bohai Bay. The seismic response characteristic analysis, well seismic forward modeling and sensitive attribute extraction were applied to qualitatively depict the seismic response characteristics and distribution range of high quality reservoirs. The combined technique of"prestack simultaneous inversion and lithofacies fluid probability analysis" was used to obtain the probability body of sandstone reservoir in the second member of Shahejie Formation in the study area. Based on the data from 21 wells in Jinzhou 25-1 oilfield, the correlation between reservoir thickness, porosity and sandstone probability was analyzed. By setting threshold, high quality reservoir development zones with thickness greater than 50 m and porosity greater than 20% were quantitatively predicted. The research results could provide a theoretical basis for the progressive exploration and well location design of Jinzhou 25-1 oilfield and its surrounding areas. The research ideas could provide a reference for high quality reservoir prediction of the second member of Shahejie Formation in other areas of western Liaoning.

New evaluation method of shale reservoir fracability based on logging data

ZHAI Wenbao, LI Jun, ZHOU Yingcao, LIU Gonghui, HUANG Tao, SONG Xuefeng

2018, Vol.30(3): 112–123 Abstract ( 362 ) PDF (1630 KB) ( 631 )

doi: https://doi.org/10.12108/yxyqc.20180313

There are many factors that affect the fracability of shale reservoirs,so it is difficult to establish a continuous and complete evaluation method for shale reservoirfracability.Due to the advantage that we can obtain continuous and complete stratigraphic information from logging data,based on the influences of shale brittleness index,mineral composition,gas-bearing capability and fracture toughness on fracability,the fractability evaluation model of shale reservoirs in long horizontal well section was established by using analytic hierarchy process, and the catastrophe theory was introduced to form a new method for evaluating fracability of shale reservoirs.The fracability for a horizontal well in Weiyuan area of Sichuan Basin was respectively evaluated by the new method and analytic hierarchy process,and the evaluation results were compared with the actual fracture development of fractured shale reservoir from microseismic monitoring and the reservoir classification based on well logging data.The results show that the evaluation results of 11th level fracturing section based on catastrophe theory are in good agreement with the actual effective fracturing volume after fracturing and reservoir classification based on well logging data.The research results can provide theoretical basis for evaluation before fracturing and improvement of hydraulic fracturing stimulation in Weiyuan area.

Application of Wheeler transform combined with time-frequency analysis technology to lithologic reservoir characterization of Bohai Oilfield

LIU Teng, WANG Jun, ZHANG Jingsi, ZHANG Li, CAI Shaowu

2018, Vol.30(3): 124–132 Abstract ( 360 ) PDF (20226 KB) ( 358 )

doi: https://doi.org/10.12108/yxyqc.20180314

In order to study the reservoir accumulation model of lithologic reservoirs and find favorable exploration zones in block A in the gentle slope zone of Shijiutuo uplift,we need to characterize the distribution of sedimentary systems and analyze the preservation conditions and updip sealing conditions of oil and gas in the reservoir top and bottom plate. This paper firstly used time-frequency analysis technology to divide the 2D sedimentary systems of wells,and then used the Wheeler transform based on seismic data to promote the results of wells to the 3D space,to promote the rapid establishment of fine sedimentary systems framework, and carried out reservoir prediction and preservation condition analysis. The results show that: (1)adjacent to Qinnan hydrocarbonrich generation depression,the gentle slope zone in Shijiutuo uplift has good conditions for hydrocarbon collection; (2)the long-term active fault in the study area together with sand bodies in delta formed a double-type transport network,which is beneficial for the formation of lithologic reservoirs; (3)the nose-shaped structure in the gentle slope zone is an important direction and track of hydrocarbon migration,once the area in the updip direction has good sealing conditions,it can form oil and gas reservoirs. Overall, block A has favorable preservation and sealing conditions, so it is a favorable exploration zone of lithologic reservoirs.

Logging fracturing evaluation for tight clastic gas reservoir and its application: a case from Denglouku Formation in Wangfu fault depression, Songliao Basin

ZHANG Shaolong, YAN Jianping, TANG Hongming, SUN Hong, WANG Min, DONGZheng

2018, Vol.30(3): 133–142 Abstract ( 297 ) PDF (2294 KB) ( 473 )

doi: https://doi.org/10.12108/yxyqc.20180315

Tight clastic gas reservoir of Denglouku Formation in Wangfu fault depression,Songliao Basin, is characterized by well-developed interlayers, multiple sets of gas water cycles and great difficulty in fracturing deve lopment. In order to overcome these difficulties for efficient production,combined with the data of core analysis, dipole shear wave and conventional logging,analytic hierarchy process was used to determine the parameters which are sensitive to reservoir fracturing property and their weight. The prediction method of fracturing height for tight clastic gas reservoir with interlayer well-developed was established after dividing fracturing grade. The results show that the sensitive parameters of fracturing evaluation for the tight and thin reservoirs of Denglouku Formation in Wangfu fault depression are brittle mineral content,brittleness index, Young's modulus and Poisson's ratio. Reservoirs with high content of brittle minerals,large brittleness index,large Young's modulus and low Poisson' ratio often have good fracturing property. When the comprehensive fracturing coefficient is greater than 0.55,the reservoir fracturing grade is grade I,which is suitable for fracturing development. There is a good ap plication effect on predicting the fracturing height of Denglouku Formation in well C11 by this method. The fractur ing height of the target zone is 7.125 m without water in the exploration process when the fracturing pressure is 33.5 MPa. The prediction results are in accordance with the actual fracturing results. The research results provide a technical basis for the effective exploitation of tight gas reservoirs.

Reservoir configuration and remaining oil distribution patterns of nearshore subaqueous fan: a case from E₃¹ reservoir in Qigequan Oilfield, Qaidam Basin

CHANG Haiyan, YAN Yaozu, CHEN Gengxin, GUO Ning, XIANG Yiwei, YANG Huijie

2018, Vol.30(3): 143–152 Abstract ( 377 ) PDF (2849 KB) ( 463 )

doi: https://doi.org/10.12108/yxyqc.20180316

In order to solve the development difficulties caused by rapid phase change of reservoir and strong heterogeneity in nearshore subaqueous fan,taking the E31 reservoir of Qigequan Oilfield in Qaidam Basin as an example,through lithology description and analysis of coring holes,combined with casting thin section and logging curve characteristics,the reservoir configuration units division and well-tie section comparison were carried out. With the aid of the dynamic data of dense well network,the sand body distribution characteristics and scale in the reservoir configuration units were defined,and the identification chart of the configuration units at all levels and the internal configuration pattern of the nearshore subaqueous fan were established. The results show that the target layer E31 can be divided into root fan,middle fan and end fan subfacies from bottom to top,and subdivided into five fifth-order configuration elements and nine fourth-order configuration elements. There are five remaining oil distribution patterns of E31 reservoir,including remaining oil formed by fault sheltering,remaining oil in non-mainstream line detention zone,remaining oil formed by rhythmic differences between different configuration units, remaining oil formed by dam-permeability buffer zone and remaining oil formed by insufficient formation of injection wells. The results can provide a geological basis for the further exploration of Qigequan Oilfield.

Supercritical and non-supercritical CO₂ flooding characteristics in tight sandstone reservoir

SHANG Qinghua, WANG Yuxia, HUANG Chunxia, CHEN Longlong

2018, Vol.30(3): 153–158 Abstract ( 258 ) PDF (1466 KB) ( 467 )

doi: https://doi.org/10.12108/yxyqc.20180317

Slim tube displacement test results indicate that CO2 miscible flooding in tight sandstone reservoir in northern Shaanxi cannot be implemented. In order to define the contribution and the influence rule of supercritical CO2 properties on displacement characteristics in the condition of immiscible flooding,supercritical and non-supercritical CO2 oil displacement experiments were conducted. The results show that supercritical state of CO2 has a positive influence on oil displacement,and the small change of pressure near by the supercritical pressure point from non-supercritical to supercritical can bring a great difference of driving characteristics. After 0.5 PV cumulative injections,the effect of supercritical CO2 flooding is significantly better than that of non-supercritical flooding. The advantage stage for supercritical flooding is mainly when the cumulative CO2 injections reach between 0.5 PV and 1.5 PV,the recovery is about 10% higher than that of non-supercritical flooding under the same conditions. The oil change ratio of supercritical flooding and non-supercritical flooding occurs peak nearly at the same injection time (about 1 PV), but the former is significantly higher than the latter. In short,whether in the injection performance,or in the oil displacement efficiency and oil change ratio,supercritical flooding is better than non-supercritical flooding.

Productivity prediction of horizontal wells by volume fracturing in volcanic reservoirs

PAN Youjun, JING Wenbo, XU Ying, ZHAO Sijun, LI Jicheng, TAO Denghai

2018, Vol.30(3): 159–164 Abstract ( 289 ) PDF (1229 KB) ( 169 )

doi: https://doi.org/10.12108/yxyqc.20180318

The main factors that affect the productivity of horizontal wells in ND volcanic reservoir are uncertain, and the conventional productivity calculation formulas for horizontal wells predict high productivity with large error. Based on the geological, engineering and dynamic data of volume fracturing of horizontal wells in ND volcanic reservoir, the influencing factors of initial productivity after volume fracturing were analyzed by grey correlation analysis. On this basis, normalized productivity of single well was accumulated by grey theory, and then multiple linear regression method was used to predict the initial productivity after fracturing. The results show that the first four factors influencing the initial productivity after volume fracturing are the amount of sand in the well,the drilling rate of the oil layer,the amount of the well fluid and the number of fracturing stage. After normalization,the initial productivity predicted by multiple linear regression after volume fracturing is more accurate than that predicted by traditional direct multiple linear regression method. This study provides an effective method for predicting productivity of horizontal wells in similar reservoirs.