Shi J.-C.,Petrochina |
Shi J.-C.,National Engineering Laboratory for Low Permeability Petroleum Exploration and Development |
Shi J.-C.,Northwest University, China |
Qu X.-F.,Petrochina |
And 10 more authors.
Natural Gas Geoscience | Year: 2016
The micro-porosity structure of tight oil reservoir is complex, and distribution characteristics of the fluid in tight oil reservoir are very different from that of low permeability reservoir. The movable fluid evaluation of the Chang 7 reservoir in the Ordos Basin was conducted by using nuclear magnetic resonance (NMR) technology, and the controlling factors of the differences in the movable fluid were analyzed by cast thin section, scanning electron microscopy, high pressure mercury injection, high-resolution computed tomography. The results show that T2 pattern of the tight oil reservoir displays six modes, the content of the immovable fluid is high in middle and large pore, which lead to the parameters of movable fluid being low, and the amplitude of variation and the differences in tight oil reservoir are large among different samples. The relationships are higher between the reservoir permeability and the parameters of movable fluid. The physical properties of the reservoir are better, and the change of the movable fluid parameters is greater. The microstructure characteristics of the tight oil reservoir, such as the distribution of pore and throat radius, development degree of induced porosity and connectivity between pore and throat radius, development degree and availability of micro-fracture, the content, the occurrence states, and the filling degree, are the main controlling factors to cause deviation of movable fluid parameters. © 2016, Science Press. All right reserved.
Zhang D.-F.,Petrochina |
Liu X.-S.,Petrochina |
Liu X.-S.,National Engineering Laboratory for Low permeability Petroleum Exploration and Development |
Gao X.,Petrochina |
And 2 more authors.
Natural Gas Geoscience | Year: 2016
Well Yutan-1 obtained 34 600m3/d natural gas production in the karst porous fractured reservoir of Kelimoli Formation in western Ordos Basin.According to the geochemical characteristics of source rock and a comparative analysis on carbon isotope of natural gas, it belongs to the oil type gas.This work has the extremely important geological significance for us to rediscover the marine carbonate exploration field of the western Ordos Basin.Through the analysis of the Ordovician paleogeographic evolution, the marine hydrocarbon source rock characteristics, reservoir characteristics and reservoir forming patterns in western Ordos Basin, the article concluded: (1) The western Ordos Basin develops two sets of effective hydrocarbon source rocks: Upper and Lower Paleozoic groups.The Upper Paleozoic marine hydrocarbon source rocks have good hydrocarbon generation ability.(2)This area develops karst porous fractured reservoir, dolomite reservoir and reef -type reservoir.Reservoir performance is better.The karst porous fractured reservoir and dolomite reservoir widely distributed.(3)The western basin develops two sets of effective accumulation patterns, “upper-generation and ldown-preservation type” and “self-generation and self-preservation type”.The western thrust zone and the western part of Tianhuan Sag, belong to self-generation and self-preservation type.The Eastern part of Tianhuan Sag belongs to upper-generation and down-preservation type.Karst porous fractured reservoir and dolomite reservoir are the favorable exploration target area. © 2016, Science Press. All right reserved.
Liu X.-P.,Petrochina |
Liu X.-P.,National Engineering Laboratory for Low Permeability Petroleum Exploration and Development |
Liu Y.,Petrochina |
Liu Y.,National Engineering Laboratory for Low Permeability Petroleum Exploration and Development |
And 4 more authors.
Natural Gas Geoscience | Year: 2016
A detailed study about the micro-pore structure and reservoir seepage characteristics was carried out on the 8th section of Shihezi Formation of Upper Palaeozoic in Ordos Basin, based on casting thin sections identification, onstant-rate mercury injection, high-pressure mercury injection, gas water phase permeability, water lock damage and stress sensitive analytical techniques, then give the improvement suggestions about drilling and reservoir reconstruction for tight sandstone gas reservoir development technology. The results are as follows: Gas reservoir in the 8th section of Shihezi Formation is tight sandstone gas reservoir. The main peak of the pore radius distribution is between 70-200 μm, and the main peak of throat radius distribution is between 0.2-2.2 μm, so the reservoir belongs to big hole, medium-fine throat type reservoir. The reservoir permeability was divided into four levels, such as greater than 1millidarcy, 1.0-0.5 millidarcy, 5-0.1 millidarcy, and 0.1-0.01 millidarcy. The throats whose radius is smaller than 0.0624 μm respectively takes up the 18.8%, 38.4%, 57.3% and 71.6% pore volumes in four lever permeability, so it is obvious that the small throats take up pore volume much higher, and throat radius size determines the reservoir permeability and also controls the reservoir seepage characteristics. Water locking and stress sensitivity are the main factors that influence the He 8 section tight sandstone reservoir seepage ability. Pressure coefficient of He 8 gas reservoir is low, and hyolrophilic preperty of the reservoir is stong, prone to water locking damage, gas permeability decreases sharply with the increase of water saturation. With pipe bundle and necking shape throat development, He 8 section tight sandstone reservoir is prone to stress sensitivity damage, and the stress sensitivity damage rate of He 8 section ranges from 40% to 80%. Volume fracturing should be widely used to reduce the control of small throat for pore in reservoir reconstruction of He 8 section tight sandstone reservoir. In drilling and reservoir reconstruction process of He 8 section gas reservoir should avoid using water-based fluid and use underbalanced drilling technology, which prevent the water-based fluid invading. In development process, the tight sandstone gas reservoir should avoid great production pressure drop and frequent switch well, and active drainage gas recovery so to protect reservoir and improve gas recovery. © 2016, Science Press. All right reserved.
Li X.,China National Offshore Oil Corporation |
Li X.,China University of Petroleum - Beijing |
Zhou J.,National Engineering Laboratory for Low Permeability Petroleum Exploration and Development |
Zhou J.,Petrochina |
And 4 more authors.
Shiyou Kantan Yu Kaifa/Petroleum Exploration and Development | Year: 2012
On the basis of the basic principles of optimization algorithms and classification algorithms, the Self-Organizing feature Map neural network (SOM) is applied to establish the predictive model of lithology for the K-Means optimized data set including core data, logging data and well tests data. Additionally, the decision tree and support vector machine are used to build the predictive model of fluid on the basis of the lithology identification. The optimization algorithms, including genetic, grid and quadratic, are adopted to optimize the important parameters of C-SVC and υ-SVC, such as C, υ and γ, so as to accurately identify the complex lithologies and multiphase fluids of complicated reservoirs. The SOM model and the decision tree and support vector machine are utilized to process four new wells in the complicated Carboniferous reservoirs of the Wucaiwan Sag, eastern Junggar Basin. The accuracy of lithology identification is 91.30%, and the accuracy of fluid identification is 95.65%. The lithologic complexity is not the main factor leading to the differences of fluids in the reservoirs. Because the complexity and nonlinearity of data set are not strong enough, the accuracy of the decision tree model is better than that of the support vector machine. Their accuracy rates are 94.31% and 86.97%, respectively. The performance of linear polynomial function is better than that of the radial basis function RBF and the neural function Sigmoid. The classification performance and generalization ability of C-SVC are stronger than that of the υ-SVC.
Shi Y.,National Engineering Laboratory for Low Permeability Petroleum Exploration and Development |
Shi Y.,Petrochina |
Li W.,Northwest University, China |
Wang C.,National Engineering Laboratory for Low Permeability Petroleum Exploration and Development |
And 4 more authors.
Geological Bulletin of China | Year: 2016
The sedimentary environment of the Chang 7 Member of Triassic Yanchang Formation in Ordos Basin is lacustrine facies with the background of large area mudstone deposition in the deep lake. The turbidity current deposits are widespread, and are characterized by extensive sedimentary range, large thickness, and proximal hydrocarbon source rocks. With these favorable factors, the Chang 7 Member has become the advantageous reservoir of oil. It is therefore necessary to find out the characteristics of sedimentary facies of the turbidite fan and sand bodies formed from different microfacies which affected the oil accumulation. Based on the analysis of the field outcrop and the core statistics, the authors divided turbidite fan microfacies in detail, which helps to study the turbidite formation, distribution, and sedimentary characteristics. According to previous research results, the channel turbidite fan with fixed supply and the channel turbidite fan with no fixed feeder were named respectively slope moving turbidite fan and slumping turbidite fan. On the basis of differences in thickness of single sand, turbidite types and formation locations, the authors divided the slope moving turbidite fan into three subfacies, i.e., upper fan, middle fan and the edge of the fan. The three subfacies contain six microfacies, such as the main channel and the overflow deposits. The slumping turbidite fan facies was divided into two subfacies, i.e., central fan and marginal fan. The recognition of microfacies of the turbidite fan and the study of their formation can help the log work to identify favorable sand body, distinguish different oil and gas reservoirs, and control the distribution of oil and gas. Massive texture sand bodyand layers sand body help to find the favorable oil and gas reservoir. © 2016, Science Press. All right reserved.
Liu A.-H.,Gas Technology Institute |
Liu A.-H.,National Engineering Laboratory for Low Permeability Petroleum Exploration and Development
Xiandai Huagong/Modern Chemical Industry | Year: 2015
Based on the water quality in Qinghua oil field, a barium sulfate scale inhibitor TH-60 is developed by using polyepoxy succinic acid (PESA), surfactants, additives and solvent. The result shows that TH-60 has scale inhibiting performance to barium, strontium and calcium ions, especially to barium sulphate. The scale inhibition rate to barium sulphate can reach 75% when the concentration of SO42- and Ba2+ and TH-60 are 1600 mg/l, 700 mg/l and 100 mg/l, respectively. ©, 2015, China National Chemical Information Center. All right reserved.
Meng X.,Petrochina |
Meng X.,National Engineering Laboratory for Low permeability Petroleum Exploration and Development |
Zhang H.,China National Petroleum Corporation |
Feng Q.,Petrochina |
And 7 more authors.
Oil and Gas Geology | Year: 2013
In order to further reveal natural gas reservoir forming conditions and its main controlling factors in Shenmu gas field, Ordos Basin, this paper systematically analyzed the hydrocarbon generation conditions, reservoir characteristics, reservoir and seal conditions, source-reservoir-cap assemblage and key controlling factors of gas accumulation in the Taiyuan Formation by using theories of petroleum geology and hydrocarbon accumulation in combination with geochemical characteristics. The results indicate that Benxi Formation, Taiyuan Formation and coal seams in the 2nd member of Shanxi Formation are high quality source rocks for the Taiyuan Formation reservoir, and have high organic content which is favorable for hydrocarbon generation. The shale in the 2nd member of Shanxi Formation has dual sealing mechanisms(i. e. capillary seal and hydrocarbon concentration seal)with strong sealing capacity, which are favorable for hydrocarbon preservation. The reservoir lithology of the Taiyuan Formation is dominated by quartz sandstone and lithic quartz sandstone with low porosity and low to extra-low permeability due to the control of both provenance and sedimentation. However, local high-yield pay zones still exist due to the development of quartz sandstone reservoirs. Physical properties are the main factors controlling hydrocarbon accumulation of the Taiyuan Formation in this area. Mapping quartz sandstone distribution is the key to reduce drilling risk and to ensure high yield of gas wells.
Yang H.,Petrochina |
Yang H.,National Engineering Laboratory for Low permeability Petroleum Exploration and Development |
Liu X.,Petrochina |
Liu X.,National Engineering Laboratory for Low permeability Petroleum Exploration and Development |
Natural Gas Industry | Year: 2013
Industrial gas flow was obtained in Shancan-1 and Yu-3 wells in the Ordos Basin in 1989 and the Jingbian Gas Field was discovered by then as the largest marine carbonate gas field in China, which confirms the huge potential of gas exploration in the lower Paleozoic marine carbonate reservoirs in this basin. In order to promote the early buildup of another Daqing in West China and provide robust technical support for further exploration in the Jingbian field, a summary was made of the main controlling factors of gas pooling in this study area as well as the involved technical approaches to gas exploration. Through the integrated analysis of depositional characteristics, source rock conditions, reservoir types and reservoir forming assemblages, three exploration domains in this Ordovician marine carbonate-developed basin were determined including the middle and eastern Ordovician weathering crust, dolomites in eastern Central paleouplifts, karst fractures and caverns in the west. After recent years' efforts in geological research and technological breakthrough, the main controlling factors of gas pooling in the above exploration domains have been well understood and a complete set of techniques have been formed such as a fine description of paleokarst landforms, forecast of weathering crust reservoirs, seismic prediction of dolomite reservoirs and detection of their gas-bearing property, recognization of fractures and caverns and reservoir prediction, and so on. Thus, new progress has been made in gas exploration in this study area. The discovered gas-bearing area in the Jingbian field has been increasing and gas reserves there nearly doubled, which is a realistic goal for the PetroChina Changqing Company to enhance its reserves and production. Multiple gas enrichment zones have been discovered in the dolomite reservoirs in the eastern Central paleouplift with natural gas in place of close to 100 billion m3, which is a realistic alternative domain. New signs of gas pooling have been found in the fractures and caverns in the western basin, which is a new area of further gas exploration.
Ren D.,Northwest University, China |
Sun W.,Northwest University, China |
Zhao J.,Petrochina |
Zhao J.,National Engineering Laboratory for Low Permeability Petroleum Exploration and Development |
And 3 more authors.
Zhongguo Kuangye Daxue Xuebao/Journal of China University of Mining and Technology | Year: 2015
Due to the poor situation of microscopic waterflooding mechanism research on Chang 81 reservoir in Huaqing oilfield of Ordos basin, the authors quantitatively studied the influence factors of waterflooding characteristics and oil displacement efficiency by waterflooding seepage experiment with real sandstone micromodel, and test data of reservoir property, constant-speed mercury injection as well as nuclear magnetic resonance. The size and distribution of throat radius were also found closely related with the waterflooding seepage law. The results show that the microscopic seepage paths of Chang 81 reservoir include uniform displacement, mesh-uniform displacement, finger-mesh displacement and finger displacement, and their correspondent oil displacement efficiency reduces in turn under the same experimental conditions. More than 70% of residual oil flow around the grain or as an oil slick. Reservoir property, pore structure and saturation of movable fluid are controlled by diagenesis, which has consistent impact on waterflooding mechanism. Generally, when the permeability is greater than 1.5 mD, the throat radius is greater than 0.5 μm, the sorting coefficient is greater than 0.15, the saturation of movable fluid is greater than 40%, the displacement pressure increasing rate is greater than 50% and displacement velocity exceeds 0.012 mL/min, the increasing trend of oil displacement efficiency will be obviously weakened. This paper proposes that oil recovery data and the core waterflooding seepage experiment should be emphasized in the process of reservoir exploitation, and priority should be given to reservoir with high permeability in designing reasonable exploitation techniques and procedures. © 2015, China University of Mining and Technology. All right reserved.
Wang S.-F.,Petrochina |
Wang S.-F.,National Engineering Laboratory for Low permeability Petroleum Exploration and Development |
An W.-H.,Petrochina |
An W.-H.,National Engineering Laboratory for Low permeability Petroleum Exploration and Development |
And 6 more authors.
Natural Gas Geoscience | Year: 2013
Ordos basin with abundance of tight gas is a backup area of natural gas exploration. Based on reviewing tight gas development and present situation, we discuss the characteristics of Sulige tight gas reservoirs as a typical case and compare the features of geological background and gas reservoir between American developed tight gas field and Sulige gasfield. Four types are classified. Based on development history and test results, we conclude development difficulties and challenges of tight gas reservoir, and point out the the following research direction in the future.