石油实验地质

2016, 38(S1): .

Abstract(394) PDF-CN(768)

Abstract:

Reservoir seismic response and prediction of Lianglitage Formation in Ka1 area, central Tarim

Ren Lidan, Liu Jun, Sha Xuguang, Zhang Kaituo, Wang Laiyuan

2016, 38(S1): 1-4. doi: 10.11781/sysydz2016S1001

Abstract(790) PDF-CN(296)

Abstract:
In the of the central Tarim Basin, carbonate reservoirs are found rich in oil and gas; however, they have a strong heterogeneity and show complicated reflection characteristics, which makes it difficult for reservoir identification and prediction. We studied reservoir response characteristics through the analyses of reservoir features and controlling elements of the Lianglitage Formation in Ka1 and Shunxi areas, and proposed some methods for reservoir identification and prediction combined with paleogeomorphy, fault and attribute analyses. Nine traps were determined according to the characters of structure, fault and paleogeomorphy. Well ZL1 was deployed based on petroleum accumulation period and enrichment regularity.

Causes and countermeasures for the sticking of electric imaging logging instrument in carbonate rocks, Tahe oil field

Cui Guang, Luo Fengming, Yin Bei

2016, 38(S1): 5-7. doi: 10.11781/sysydz2016S1005

Abstract(738) PDF-CN(318)

Abstract:
In the recent explorations in the Tahe oil field, electric imaging logging instruments are often stuck due to castings from borehole wall and fracture development. Some countermeasures were proposed, such as wellbore preparation, operation after optimization sticking, and project substitution. Some fishing treatments after sticking were suggested.

Fault characteristic and reservoir controlling in ShunX well area, central Tarim

Wang Laiyuan, Gong Wei, Liu Jun, Ren Lidan, Wang Peng

2016, 38(S1): 8-12. doi: 10.11781/sysydz2016S1008

Abstract(714) PDF-CN(221)

Abstract:
Based on regional geology and seismic data, the NE strike-slip faults are developed by the redefinition of fault active period, which shows paralleled high-steep continental strike-slip fault from the Early Caledonian to episode I of the Mid-Caledonian, extensional en-echelon tulip-flower structure during episode I of the Mid-Caledonian to the Early Hercynian period, and compressional en-echelon positive-flower structure during the Mid-Late Hercynian. NE strike-slip and NW zoning of sinistral strike-slip tectonic framework is formed by NE strike-slip fault of wells ShunX1, ShuntuoX2 and ShunX3. Weak NW-striking concealed faults are found in the study area. Cave and fracture reservoirs of carbonate rocks are certain controlled by fractures formed by NE strike-slip faults and following hydrothermal activities, which forms zone distribution of seismic reflection moniliform along NE strike-slip fault within 10 km (3.4 km in average), and most developed in cross position within NE strike-slip fault and weak NW-striking concealed faults.

Research and application of drilling fluid suitable for new well bore structure in the Shunbei oil field

Xie Hailong

2016, 38(S1): 13-18. doi: 10.11781/sysydz2016S1013

Abstract(793) PDF-CN(256)

Abstract:
In the Shunbei oil field, leakage often took place in Permian, well bores are instable in Silurian, collapse stress is high in the Sangtamu Formation, and it is difficult to carry debris directionally in deep and slim holes. A new well bore structure with special intrusion for sealing is proposed. Through laboratory experiments, we choose polyethylene amine, high softening point asphalt, sulphonate copolymer treating agent such as methy-lamine, and introduce methylamino drilling fluid and filming technique, to deal with longitudinal cracks in Permian. Field applications were made in 5 wells, and proved successful. A set of suitable drilling fluid technology has been developed to meet the needs of new well structure.

Application of multi-wavelet decomposition technique to reservoir prediction: A case study of the Yijianfang Formation in SN block, Tarim Basin

Yang Yujie

2016, 38(S1): 19-22. doi: 10.11781/sysydz2016S1019

Abstract(921) PDF-CN(219)

Abstract:
Good oil and gas shows were found in strong wave trough of the Yijianfang Formation in SN block of the Tarim Basin. Due to the shielding effect of the strong wave peak of T₇⁴ interface, general amplitude property could not effectively predict reservoir distribution while forward results also had multiple solutions. Multi-wavelet decomposition and reconstruction technique as well as the third component were introduced to predict reservoirs in the study area. The reservoir boundary and range predicted based on lower seismic tracks agreed with those based on the third component and drilling results. Zones with high amplitudes are favorable for reservoir development. Multi-wavelet decomposition technique can remove the influence of strong axis, and get a better reservoir recognition result.

Sporo-pollen assemblages in Yubei area, Tarim Basin and a discussion on its age

Hu Mei, Cheng Junfeng, Wei Ling

2016, 38(S1): 23-26. doi: 10.11781/sysydz2016S1023

Abstract(563) PDF-CN(154)

Abstract:
The sporo-pollens of the Devonian-Paleogene in Yubei area, the Tarim Basin are divided into 9 assemblages on the basis of 324 samples derived from 8 wells and combining with the latest achievements of stratigraphic research. The sporo-pollen assemblages indicate that the stratigraphic age is from the late Devonian to the early Oligocene. The studies of sporo-pollen assemblage and its age provide a biostratigraphic evidence for stratigraphic division and age determination, and are helpful for field practices.

Prediction of cyclic gas injection volume in Dalaoba condensate gas reservior

Chen Yingchao, Zhang Kui, Wang Han

2016, 38(S1): 27-31. doi: 10.11781/sysydz2016S1027

Abstract(667) PDF-CN(220)

Abstract:
The Dalaoba condensate gas reservoir belongs to the deep condensate gas reservoir with edge water of high temperature and pressure, high wax content and condensate content. During the process of depletion deve-lopment, retrograde condensation and water invasion often occur, resulting in the sharp decline of gas well productivity. Cyclic gas injection is applied to enhance gas reservoir recovery. Since cyclic gas injection was carried out during the middle-later period of the reservoir's development, for ensuring cyclic gas injection's recovery efficiency and economic benefit, the relationship was analyzed through simulation method between condensate content changes and cumulative oil and gas output after implementing gas injection for water-drive condensate gas reservoir, such as Dalaoba condensate gas reservoir. It was determined that condensate oil content would drop to 100 g/m³ in 2029, and the cumulative volume of gas injection would reach 24.65×10⁸ m³ at that time. The exploitable geological reserves would be optimized under economic condition, thus ensuring the development effect of cyclic gas injection.

Capillary pressure curves to determine gas-water contact in sandstone reservoirs

He Yunfeng, Zhang Ai

2016, 38(S1): 32-35. doi: 10.11781/sysydz2016S1032

Abstract(905) PDF-CN(255)

Abstract:
In the drilling of well S45, which is on the edge of the Upper Suweiyi Formation in Dalaoba-2 structure, we did not find the gas-water contact, and took the sand bottom boundary of this well as gas-water contact in reserve calculation, which led to a big error and seriously affected the authenticity of reserves. This paper, based on the principle of capillary pressure, used reverse-hinking, and calculated the height of gas by gas saturation, and then determined the gas-water contact for gas reservoir. Using this method, we calculated the gas-water contact for the Lower Suweiyi Formation of Dalaoba-2 Structure, and it was nearly the same as the actual gas-water contact. We also calculated the gas-water contact for the Upper Suweiyi Formation, and then predicted reserve.

Coupling water injection in channel sand reservoirs

He Xueqin

2016, 38(S1): 36-38. doi: 10.11781/sysydz2016S1036

Abstract(785) PDF-CN(158)

Abstract:
Channel sandstone reservoirs in the Tahe oil field have strong plane heterogeneity. Sand bodies are thick and show favorable physical properties in channel center, and become worse to the sides. As a result, oil remains in wells in great quantities. Water injection for energy supply is necessary to enhance production even though small-scale edge water exists locally. Conventional continuous water injection is effective during the early stage; however, it is difficult to govern water breakthrough. Optimized injection way, injection-production ratio, water injection amount and cycle were put forward and proved effective after practicing in channel sand reservoirs in Triassic, T5 well block.

Superimposed plates of energy curves to enhance oil recovery of carbonate reservoirs

Chen Mingren, Jiang Lin, Li Chenggang, Cheng Lu, Liu Cong, Lu Haitao

2016, 38(S1): 39-43. doi: 10.11781/sysydz2016S1039

Abstract(688) PDF-CN(264)

Abstract:
Carbonate reservoirs in the Tahe oil field are composed of dissolved pores, karst caves and fractures, among which the fractures are the main seepage pathways. The reservoirs are deep buried and usually have a strong heterogeneity. The study of pre-production and well performance data indicated that, formations collapsed and cracks closed in production process due to the decrease of formation energy, resulting in insufficient liquid supply during post-oil production. Therefore, we applied energy indicating curves to guide production, and made some achievements. The Tahe wells have a complicated oil and water contact, and some well bores have abnormal conditions, which are restrictive for energy indicating curves. We divided the curves to several different types, and analyzed their corresponding reservoir geological reasons. We also considered water content and water flooding, and converted pressure to load, and finally made a superimposed plate of energy curves to guide production.

Pilot test for gas production of fractured-vuggy condensate gas reservoir by water injection in Tahe oil field

Li Zongrui, Hao Yang

2016, 38(S1): 44-47. doi: 10.11781/sysydz2016S1044

Abstract(681) PDF-CN(124)

Abstract:
The X25 well block in the Tahe oil field is a condensate gas reservoir with fractured-vuggy carbonates in Ordovician. Its substrate does not reserve oil and gas, and the main reservoirs are cracks, holes and caves. This area is mainly single well units, lacking of natural water energy. Production performance shows significant volume characteristics. With the decline of formation energy, gas wells stop producing by pumping due to deep liquid level. Facing such dilemma, we innovated a pilot test with water injection. Water was injected into gas well to supply energy and compress gas volume, hence made production continued. The success of this experiment explored a new EOR way in such gas reservoirs.

Study and application of connecting relationship during water injection of well groups in carbonate reservoirs, Tahe oil field

Li Guiyun, Tian Lei, Huang Mina, Lu Haitao, Ren Ke, Liu Hongyuan

2016, 38(S1): 48-51. doi: 10.11781/sysydz2016S1048

Abstract(632) PDF-CN(189)

Abstract:
In the initial attempt of water injection in carbonate fractured-vuggy reservoirs in the Tahe oil field, only a few wells were effective, and the relationship between water injection and production was unclear. Based on the systematic analyses of production dynamic variety during different stages of water injection wells and oil producing wells, three methods, including unit differential pressure curve, energy nodal analysis, and high-pressure water injection to balance well group energy, were summarized to establish well group link and make clear well relationship. Unit differential pressure curve deals with the well group which injecting in multiple wells and producing in a single well, and can determine the connective response among wells. Energy nodal analysis focuses on the changing points on energy indicating curves of oil wells, and shows the relationship between injection and production among wells. For those well groups with differential pressure and were not effective during water injection, we use high-pressure injection to balance energy and establish well group link. With these methods, we determined well relationship and dynamic response, established injection and production well group, guided the production of well group, promoted water injection development level, and enhanced Tahe oilfield reserves production.

Prevention of asphaltene chokes in Ordovician oil production wells, district X, Tahe oil field

Huang Liangshuai, You Jiayu, Li Dandan

2016, 38(S1): 52-55. doi: 10.11781/sysydz2016S1052

Abstract(840) PDF-CN(155)

Abstract:
Nowadays, some Ordovician oil production wells are shut down because of asphaltene chokes in oil pipes and surface pipeline system, which has seriously affected production progresses. In order to solve this problem, we have conducted a comprehensive study on asphaltene deposition and finally obtained an effective method for asphaltene choke prevention in oil production wells. Through the study of crude oil components and asphaltene deposition in district X, we found that high content of saturated hydrocarbons and low colloid asphaltene ratio are the main causes leading to asphaltene deposition. According to these studies, we have developed some methods to prevent asphaltene chokes including mixing in asphalt dispersant, clearing slug away and optimizing ground processes. These methods have effectively solved the problems after experiments.

Differential countermeasures for Ordovician reservoirs in X area, Tahe oil field

Zhang Li, Wang Jiale, You Jiayu, Zhang Ying, Wang Xilin, Gao Hui, Gan Lili

2016, 38(S1): 56-61. doi: 10.11781/sysydz2016S1056

Abstract(521) PDF-CN(160)

Abstract:
The X area is located in the northeastern structural high of the Tahe oil field. The surface of Ordovician weathering crust is lower in the south and higher in the north. Monadnocks are well developed in the study area. Fractures and caves work as the main reservoirs. Due to poor connectivity, the dynamic characteristics of hydrocarbon exploration vary among areas. The central and western parts, with well-developed reservoirs, are abundant in hydrocarbon. The western part faces a risk of bottom water coning, hence is difficult to stabilize crude output. Wells in the central part have poor formation energy, and show a low recovery rate. The southeastern area has a relatively lower tectonic location and thin hydrocarbon layer, is featured by fast water-cut rising and poor water control effect. For differential characteristics, based on dynamic and static analyses, this study presents some corresponding countermeasures, such as reasonable mining speed control, injecting water to replace oil, water injection unit, single and unit well gas injection. Besides, this study deepens the knowledge on Ordovician reservoir exploitation, improvea area productivity to a certain extent, and slows down oil production decline. Furthermore, this study provides a guidance and reference significance to expand productivity construction and improve producing reserve.

Application and research of quantitative water injection to improve oil recovery in Tahe carbonate oil field

Ren Ke, Jiang Lin, Huang Mina, Liang Sha, Tang Bochao, Li Guiyun

2016, 38(S1): 62-65. doi: 10.11781/sysydz2016S1062

Abstract(662) PDF-CN(157)

Abstract:
Carbonate reservoirs in the Tahe oil field are featured by great burial depth and strong heterogeneity. Oils mainly reserved in dissolved pores, caves and fractures, while fractures worked as the main seepage way. As formation energy decreases in oil field, water injection has become a most promoted way to supply energy thanks to high economic returns. According to the principle of material balance, with acid fracturing curve, water flooding curve and energy curve, we calculated the volume of water, made a better understanding of the relationships between water injection and recovery, and then optimized injection-production parameters, to improve the water flooding efficiency and oil recovery.

Cementation of long open hole in Shunbei block, Tarim Basin

Wang Yonghong, Li Fei, Dong Ruiqiang

2016, 38(S1): 66-70. doi: 10.11781/sysydz2016S1066

Abstract(915) PDF-CN(127)

Abstract:
The Shunbei block in the Tarim Basin has complicated geologic conditions, and reservoirs are deep buried, usually over 7 500 m. Pyrolith in Permian leaks seriously. The Silurian formation has a poor pressure resistivity. The Upper Ordovician develops diabase intrusion body, and has a strong collapse stress. To optimize well structure, we used 193.7 mm casing down to the top of intrusion body, facing some difficulties such as deep setting depth (7 000 m) and cementing leakage. We improved cementing slurry column structure and centralizer design, added temperature-sensitive memory plugging material into light-weight cement slurry, optimized leakproof cementing technology, and injected light-weight cement slurry from well hole. In this way, the cementation of long open hole was optimized. This technique was applied and proved effective in 5 wells by two-stage cementation in Shunbei block.

Difficulties and countermeasures of high-pressure gas well controls in Shunnan block, Tahe oil field

Li Xiang, Wang Bowei, Yang Haitao

2016, 38(S1): 71-74. doi: 10.11781/sysydz2016S1071

Abstract(880) PDF-CN(208)

Abstract:
The Shunnan block locates in the center of the Taklimakan Desert, which has many high-pressure gas reservoirs. Well control accidents have occurred when drilling in the Penglaiba Formation in a high-pressure re-servoir of the Shunnan X well, causing washouts at control system and surface casing. In order to ensure safety while drilling high pressure gas wells, we optimized well control technology and ground equipment, and preferred key fittings and ground pipe manifold matching combinations, which provided theoretical and practical basis for the safety drilling of high pressure gas wells in this area.

Deep pumping in fractured-and-vuggy carbonate reservoirs: Practices in Tahe oil field

Zhang Shiliang, Cui Yi, Guo Zhongliang, Ding Lei

2016, 38(S1): 75-77. doi: 10.11781/sysydz2016S1075

Abstract(608) PDF-CN(171)

Abstract:
As a conventional and economic technique, deep pumping has been applied gradually in fractured-and-vuggy carbonate reservoirs in the Tahe oil field, guiding by water injection curves. However, the practice of deep pumping in go-flat injection wells showed a poor efficiency. With a new understanding of deep pumping mechanism, it was found that stress was sensitive in fracture system. Fracture permeability decreased as formation pressure increased during production. As a result, when deep pumping, we should not blindly deepen fluid level and enlarge production pressure difference. Logically supplying formation energy was recommended to take packing mining.

Strengthening wellbore fluid techniques for long open-hole

Pan Lijuan, Liu Biao

2016, 38(S1): 78-82. doi: 10.11781/sysydz2016S1078

Abstract(989) PDF-CN(198)

Abstract:
The difficulty of strengthening wellbore fluid for long open-hole in X1 region is concentrated in the leakage in the upper Permian igneous rocks with developed micro fractures, and the shale collapse in the lower Silurian. Drilling fluid maintenance is difficult in the same open hole section. In well X1-1H, 8 leak points were found in Permian, and well leaked for 25 times, losing 2 568 m3 drilling fluid. In well X1, the treatment for mudstone blocking in Silurian took 22.1 days. Polymer gel plugging agent and bamboo fiber were applied to prevent leakage for 30 min at 0.69 MPa. Plugging agents for fractures of 1, 2, 3 mm were designed, which can prevent leakage at 6.9 MPa. We combined isolating membrane with hydration inhibition, introduced film-forming agent and polyamine inhibitor as key agents, and optimized form Amino potassium filming drilling fluid system for Silurian, which has a high pressure filtration volume of 8.8 mL at 150℃. Compared with KCl-polymer sulfonated drilling fluid, shale recovery increased by 15.1%. Applications in wells X1-5H and X1-6H 2 showed a good effect. No leaking occurred when drilling and completing in Permian. Almost 5 000 meters long open-hole did not stick. The average hole enlargement of Silurian was only 9.01%. Strengthening wellbore fluid techniques for long open-hole are significant to cut cost and increase profit in X1 region.

Reservoir formation conditions and accumulation laws in Mesozoic in Yuqi area

Liao Zhiyong, Kang Rendong, Cao Yuanzhi

2016, 38(S1): 83-86. doi: 10.11781/sysydz2016S1083

Abstract(652) PDF-CN(168)

Abstract:
Taking the Yuqi area in the northern Tarim Basin as an example, with fundamental geology, physical geography, geochemistry and logging data, the paper analyzed petroleum accumulation condition and reservoir model in the study area. Reservoirs can be divided into east, west and central blocks in the Yuqi area, showing significant difference between east block and west block in reservoir formation. Associated with the history data of this petroleum reservoir, some controlling factors of petroleum accumulation were proposed and the favorable exploration area of Yuqi areas was forecasted. The results can provide evidences for further petroleum exploration.

Influencing factors and countermeasures for pump current fluctuation in Tahe oil field

Liang Yanqiu, Lü Yuli, Zhou Danping

2016, 38(S1): 87-91. doi: 10.11781/sysydz2016S1087

Abstract(612) PDF-CN(149)

Abstract:
Heavy oil reservoirs in No. 2 Oil Production Plant are featured by "super depth, super thickness, high density, high viscosity, high asphaltene-containing colloid, high hydrogen sulfide content, and high salinity", which makes production difficult. Pump is the main machine for lifting, so it is very important to guarantee its normal working conditions. Current is an important parameter reflecting pump conditions, and its fluctuation reflects oil production and pump condition intuitively. This paper analyzed pump current fluctuation characteristics and proposed some countermeasures, which provided a basis for the stable production of pump in the future.

Dynamic liquid level calculation using heavy oil work diagram:A case study in Tahe oil field

Su Hongtong, Wen Bo, Yang Shiguo, Guo Yuan, Su Wei

2016, 38(S1): 92-95. doi: 10.11781/sysydz2016S1092

Abstract(647) PDF-CN(183)

Abstract:
The Tahe oil field is a carbonate ultra-deep and ultra-heavy oil reservoir featured by production based on dilution, complex oil-casing annulus environment and deep wells. Test personnel and ground interference also led to a low success probability of liquid level measurement and affected management of mechanical pumping wells heavily. This paper analyzed the main factors which influenced liquid level test in the Tahe oil field in view of the characteristics of mechanical pumping well in heavy oil reservoir. A new dynamic liquid level calculation method using work diagram load was applied to solve the difficulty of distortion of liquid level. The method can be adopted to conduct the production management of mechanical pumping wells in heavy oil reservoirs.

Lifting the depth of rod pump with deepening tail pipe and its influencing factors

Jiang Lei, Yuan Bo, Xia Xinyue, Wang Leilei, Zhao Yuan

2016, 38(S1): 96-99. doi: 10.11781/sysydz2016S1096

Abstract(833) PDF-CN(236)

Abstract:
The Tahe reservoir is a fractured-vuggy carbonate reservoir about 5 350-6 600 m deep with complicated fluid properties. The highest viscosity is 245 000 mPa·s (55℃), that is, crude oil in wellbore over 3 000 m deep could not flow. Therefore, we mixed light oil into pipes to reduce viscosity. As more heavy oil reserves have been employed, the difficulty of mechanical lifting increased. We lifted the depth of rod pump and deepened tail pipe in view of different sucker-rod pump types in heavy oil blocks in the Tahe oil field, and discussed their influencing factors. By guarantee the quality of mixed oil, we reasonably lifted pump depth in order to reduce rod load, and to improve rod pump working condition.

Application of Tahe crude oil batch transportation to Talun pipeline

Lu Zhiqian, Wang Cheng, Chen Lanxia

2016, 38(S1): 100-103. doi: 10.11781/sysydz2016S1100

Abstract(932) PDF-CN(324)

Abstract:
The batch transportation background of Tahe crude oils and the basic conditions in Talun pipelines were introduced to illustrate how medium and heavy crude oils were transported. Oil mixing rules, factors and the hydraulic characteristics of pipelines during batch transportation were concluded to guide the safe operation of Talun pipelines.

Stability of condensate oil mixed with heavy oil in Tahe oil field

Yang Zuguo, Gao Qiuying, Wu Guangsheng, Cao Chang, Gao Dingxiang

2016, 38(S1): 104-108. doi: 10.11781/sysydz2016S1104

Abstract(663) PDF-CN(297)

Abstract:
Heavy oil of the Tahe oil field has a high viscosity, high density, high content of gum and asphalt. Asphaltene deposited frequently when heavy oil mixed with condensate oil, which blocks storage tanks and ground pipelines. In view of the influencing factors on the stability of oil colloid and combined with colloid stability theory, we mixed Tahe heavy crude oil and condensate oil in different proportions. The compatibility of mixed samples was analyzed using spot experiments, and some qualitative conclusions were made. Quantitative data have been obtained by the determination of mixed crude oil stability parameters. We determined a reasonable ratio range of the two kinds of crude oil, which provided theoretical guidance for effectively solving the problem of blending and transportation of different oils.

A new technique dealing with XHP permanent packers for deep wells

Yan Keju, Wu Xingdong, Chen Biao

2016, 38(S1): 109-111. doi: 10.11781/sysydz2016S1109

Abstract(628) PDF-CN(135)

Abstract:
XHP permanent packer can effectively ensure the safe and efficient production of a deep, high temperature, high pressure, and high yielding gas well, but it's difficult to deal in the later workover process. On the basis of failure experience in early days, and combined with the analysis of the structure principle of XHP permanent packer, this paper summarizes a new technique dealing with XHP permanent packer, which can lead to a substantial increase in workover aging by changing the processing approach of packer body and seal pot, and by optimizing ring-milling tools. We first make seal pot upside down, and then salvage packer body, which provides a new method for the successful treatment of XHP permanent packer.

Exploration of coiled tubing with downhole corrosion salvage craft

Wu Jian, Wu Xingdong, Wang Ligang

2016, 38(S1): 112-113. doi: 10.11781/sysydz2016S1112

Abstract(823) PDF-CN(260)

Abstract:
Coiled tubing has been widely used in oil and gas fields both domestic and overseas at present. It is mainly used for operations of drilling, downhole operation and oil and gas production, such as sand-flushing, flowback inducing, acidizing, drainage gas recovery, drilling, and fishing fallen objects. With the application of coiled tubing more and more widely, coiled tubing often brakes, but whether it happens in casing or tubing, currently, there is no molding processing tools and reference case both domestic and overseas. A case study was made in the Yakela condensate gas field. Downhole corrosion salvage craft was applied to deal with coiled tubing, which could provide a reference for handling such problems in the future.

Salvage for MHR permanent packer in Tahe oil field

Wu Haojie

2016, 38(S1): 114-117. doi: 10.11781/sysydz2016S1114

Abstract(955) PDF-CN(237)

Abstract:
MHR hydraulic permanent packers have been used in Ordovician gas reservoirs in the Tahe oil field and the Yakela Gas Production Plant. We contrasted the removals of packers in the TK915-2X, YK14CH, TK915-4X and DLK3X wells based on MHR packer's structure and setting procedure, summed up some MHR packer salvage experiences, provided a reference for similar wells.

Open hole completion technology for carbonate leaking wells, Tahe oil field

Zhang Jia, Li Xiaosheng, Zhao Zhonghui, Yang Kun

2016, 38(S1): 118-120. doi: 10.11781/sysydz2016S1118

Abstract(850) PDF-CN(162)

Abstract:
The Tahe oil field is a carbonate fractured-and——vuggy reservoir in Ordovician. Reservoir depth averages 5 300-5 720 m, with a maximum of 7 143 m. It has a strong heterogeneity, and drilling leakage rate reached 30% with a large leaking volume, about 560 m³ of drilling fluid for each single well. Open hole completion technology was applied to leaking wells. The traditional well completion technology has some shortcomings when grouping completion pipe column and changing for wellhead. We optimized wellhead controlling technology and the safe deployment of well completion pipe string, which fundamentally eliminated hidden troubles to ensure the safety of high-risk operations, controlled well safety, and saved operation cost.

Influencing factors for natural gas desulfurization and countermeasures: A case study in No.3 Oil Production Plant,SINOPEC Northwest Company

Duan Guangyi, Zhang Qing, Zhang Xianghui, Lin Deyun

2016, 38(S1): 121-125. doi: 10.11781/sysydz2016S1121

Abstract(577) PDF-CN(366)

Abstract:
This article introduces the effects of natural gas desulfurization on production in No. 3 Oil Production Plant,SINOPEC Northwest Company. With the increasing of gas processing volume, the environment temperature of the area is rising, and the content of hydrogen sulfide in natural gas is excessive, hence the tube bundle of gas cooler frequently occurs. We compared several previous desulfurization methods and optimized desulfurization technique. Refrigeration technique can cool raw gas and lean liquid, and improve desulfurization effect, which guarantees product quality and the safe operation of processing system.

Occurrence status and mechanism of down-hole string corrosion by nitrogen injection

Ma Yan, Yang Yang, Guo Jing, Yang Rongrong

2016, 38(S1): 126-128. doi: 10.11781/sysydz2016S1126

Abstract(677) PDF-CN(190)

Abstract:
Nitrogen injection is a chief technique to efficiently improve oil recovery rate in carbonate reservoirs now. With the promotion of nitrogen injection technology, more and more corrosion failures were found in wellbores. Based on the studies of nitrogen injection technique, media and production, we analyzed the corrosion mechanism and influencing factors of down-hole strings. Results showed that the mixture of high-concentration oxygen and high salinity, week-acidic water created electrochemical corrosion and erosion corrosion, which caused whole corrosion inside pipe and pitting corrosion outside pipe wall. Corresponding countermeasures were proposed in this paper combining with field applications.

Optimization and application of PHP casing hydraulic packer in Tahe oil field

Yang Cheng, Zhang Jia, Zou Wei, Xie Jin

2016, 38(S1): 129-132. doi: 10.11781/sysydz2016S1129

Abstract(777) PDF-CN(115)

Abstract:
PHP casing hydraulic packer has been widely used in the Tahe oil field; however, with the deepening of oilfield exploration and development, its heat and pressure resistance need improment. We use thicker packer wall and more heat resistive plastic tube to upgrade PHP-2 packer, which is outstanding for high pressure diffe-rence resistivity, high temperature resistivity, recyclable and less cost compared to imported permanent packer. The optimized packer has a broad application prospect in the Tahe oil field.

Application of short liner cementing technique in casing damaged well governing of the Tahe oil field

Tian Lei, Li Guiyun, Liu Yanping

2016, 38(S1): 133-135. doi: 10.11781/sysydz2016S1133

Abstract(631) PDF-CN(238)

Abstract:
With the long-term development of water, nitrogen injection in the Tahe oil field, well casing damage becomes more and more serious, especially in some old wells, due to the long working time of casing pipe, poor cementing quality, and low casing pipe strength. Pipes often broke at casing suspension or weak parts. As a result, formation water invaded, leading to high water cut in oil wells. The main technologies for casing damage governing are seal plugging and cementing; however, they have a limited applicability and short finite time. At present, a short liner cementing technique is used in the Tahe oil field, and can solve the problem of oil well casing damage at once and forever. In this paper, through the analysis of the three types of casing damage governing methods, focusing on the advantages of the short liner cementing technique, it provides an important basis for the promotion of the technique.

Crude oil emulsion laws and countermeasures, Tahe oil field

Hu Huiguang, Zhang Yinan, Wang Rui, Du Kang

2016, 38(S1): 136-139. doi: 10.11781/sysydz2016S1136

Abstract(1601) PDF-CN(156)

Abstract:
The super deep carbonate fractured-vuggy heavy oil reservoirs in the Tahe oil field have a strong he-terogeneity and are featured by "super depth, super thickness, high asphaltene-containing colloid, high hydrogen sulfide content, and high salinity". The laws and countermeasures of crude oil emulsion in production wells were studied. The composition of emulsified oil in different wells and during different production stages were compared, founding that super heavy oil layered in formations and flowed at different speed as density changed. Du-ring the gas injection for different oils, the contents of asphalt, colloid and paraffin wax changed, resulting in oil emulsion. We usually use demulsifier, and add salt water from wellhead to reduce the viscosity of emulsified oil and enhance its liquidity. For gas injection wells, we inject foaming agent to prevent oil from contacting water, which can reduce crude oil emulsion.

Packers used in inflow control device (ICD) for completion of horizontal wells

Zhang Yi, Long Wu, Song Hai, Fang Junwei

2016, 38(S1): 140-144. doi: 10.11781/sysydz2016S1140

Abstract(928) PDF-CN(283)

Abstract:
We used packing grains to replace traditional packer in order to improve the precision of inflow control device (ICD) for the completion of horizontal wells, and to seal the whole well bore. Flows in horizontal directions can be blocked. In this way, ICD controls water flow and stabilizes oil production. It realizes the dynamic adjustment of flows in the whole horizontal well section. This new technique was applied in the second completion of the Tahe oil field. This was the first time adopting non-mechanical tools to realize packing in tube. We designed new packing materials, which can stand higher pressure and are more economic. The materials performed well in laboratory experiments, and have a good potential in new well completion and secondary completion.

Acid fracturing for complex fractures in fractured-vuggy reservoirs in Tahe oil field

Yang Yuqin, Zhao Bing, Li Nan, He Xiaobo, Hu Wenting

2016, 38(S1): 145-149. doi: 10.11781/sysydz2016S1145

Abstract(800) PDF-CN(131)

Abstract:
The main reservoir types in Ordovician carbonate formation in Tahe oil field are dissolution fractures and caves. Acid fracturing is one of the main methods of oil field development. Venting and leakage during sidetracking show that a lot of caves distributed nearby, but not connected to well because of single acid fracture extending direction. Increasing the complexity of acid fracturing may contribute to improve the probability of link between well and caves which distributed along different directions. A fracture extending compute model is proposed under the conditions of complex natural fracture. Different rock mechanic parameters which have influence on fracture's complexity are assessed:friction coefficient > horizontal stress difference > approximation angle > tensile strength > cohesion. Acid fracturing for complex fractures is applied in 5 wells, obtaining 5 909.7 t oil in average for each well.

Conductivity of acid etched fractures with high closure stress

An Na, Zhang Xiong, Fang Yuyan, Jiao Kebo

2016, 38(S1): 150-152. doi: 10.11781/sysydz2016S1150

Abstract(782) PDF-CN(192)

Abstract:
The article aims at a question that how to improve fracture conductivity with high closure stress. It researches the influences of contact time between acid and rock, types of acid, closure stress on conductivity respectively and how to improve conductivity by compound manner. It turned out that flow conductivity has a linear relationship with closure stress on semilog coordinate in same contract time between acid and rock, which means higher closure stress, lower flow conductivity. The experimental results also show that acid etching fracture has higher flow conducti-vity with big propping agent in low closure stress. It's more appropriate to choose propping agent from 40 to 70 mesh in high closure stress stratum, and the larger the sanding concentration, the higher the flow conductivity. Therefore, sanding in the acid etching stratum is one of the most effective means for improving flow conductivity.

Risk evaluation and preventive measure of buried outer pipelines in transfer station: A case study of AZ1 transfer station, area S, northwestern China

Yang Peng, An Yongfu, Chen Yang

2016, 38(S1): 153-159. doi: 10.11781/sysydz2016S1153

Abstract(1689) PDF-CN(141)

Abstract:
Crude oils went through buried pipelines by their original pressure to transfer stations after pumping out from wells. They were heated, dried and pressured, and then transported to oil-gas united stations for further complicated processing such as desulfuration, dehydration and oil-gas-water separation, and finally sent outside through long-distance pipelines. In consideration of the complexity of technological process and the dangerousness of transmission medium, an early-warning system of risks is required not only for the process of gathering and transportation, but also for the buried pipelines between wells and oil-gas united stations. Since crude oils are untreated until transporting to united stations, the buried pipelines between wells and united stations are easily to be corroded and crack. Therefore, a risk evaluation and preventive measure of buried outer pipelines are really needed. A case study was made in AZ1 transfer station, S area in an oilfield in northwestern China. We collected and counted all corrosion reasons for three years, and studied normal operations, operation risks and corrosion causes using Fault Tree Analysis (FTA). An early-warning system of risks and some preventive measures were provided.

2016 Vol. 38, No. S1

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