The increasingly mature world horizontal well technology
Horizontal well technology is highly concerned by the oil industry and is one of the drilling technologies with development potential. It represents the development direction of petroleum technology in the 21st century. At present, international famous companies such as Schlumberger, Halliburton, Baker Hughes and Weatherford have developed their own patented technologies. Its core technology has a complete set of drilling, completion, and exploitation technologies and tools and equipment for horizontal wells. The horizontal well technology in developed countries is becoming more and more popular.
This paper summarizes the key technologies and development trends through the research on the application of global horizontal well technology in development, which will surely make positive contributions to the high-level, high-efficiency exploration and development of oil and gas resources and sustainable development. (This article is funded by PetroChina's "Research on the Development Trend of the World's Oil and Gas Upstream Business and the Environment of Oil and Gas Cooperation", project number: 20080l18)
水平井技术受到石油业界高度关注，为具发展潜力的钻井技术之一。代表了21世纪石油技术的发展方向。目前国际著名大公司如斯 伦贝谢、哈里伯顿 、贝克休斯 、威德福研发出自己的专利技术。其核心技术具备了水平井的全套钻井、完井、开采等熙套技术和工具装备，发达国家水平井技术日渐成热。
The increasingly mature world horizontal well technology
口Huaiyou Koujiang/China Petroleum Institute of Economics and Technology
Kang Pingda Li Ning Zou Wenjiao/China University of Geosciences
Jiang Liangyi / Yan'an University
Qi Renli / Daqing Petroleum Institute
康平达 李宁 邹文娇/中国地质大学
Horizontal well refers to a special form of oil and gas well with a certain extension length and a horizontal well section with a well inclination close to 90 in the pay zone. Horizontal well drilling technology is developed on the basis of directional well drilling technology. General oil wells run vertically or obliquely through the oil layer, and the well section passing through the oil layer is short. In a horizontal well, after drilling vertically or obliquely to the pool layer, the barrel is transferred to a near-horizontal level and is kept parallel to the oil layer, so that the long well section can be drilled in the oil layer until the well is completed. The oil well passes through the oil layer well interval of hundreds of meters to more than 2,000 meters, and the production capacity is several times higher than that of ordinary vertical wells and inclined wells (see Picture 1).
As early as 1927, the horizontal well drilling test appeared in the world. During the 1940s and 1970s, countries such as the United Kingdom and the former Soviet Union drilled a number of horizontal well test wells. After the 1970s, the United States, Canada, France and other countries carried out research on the development of oil and gas reservoirs with horizontal wells. In the 1980s, this technology was widely industrialized and applied. In the early 1980s, the French company EifA quitaine successfully developed a carbonate heavy oil reservoir in the RospoMare oilfield in the Italian Adriatic Sea using horizontal wells for the first time. At the same time, some U.S. companies have also begun drilling horizontal wells in the AboReef field in New Mexico to mitigate water and gas coning, as well as horizontal wells in fractured natural fracture carbonate reservoirs in Oklahoma, Kansas and Texas. (See Figure 2).
早在1927年，世界上就出现了水平井钻井试验。上 世纪如40-70年代，英国和前苏联等国钻了一批水平井试验井。70年代后，美国、加拿大、法国等国开展了水平井开发油气藏的研究，进入80年代，此项技术才大规模工业化推广应用。上世纪80年代初，法司EifA quitaine 公司第一次利用水平井成功地开发了意大利亚得里亚海上RospoMare油田的一个碳酸盐岩稠油油藏。与此同时，一些美国公司也开始在新墨西哥州的AboReef油田钻水平井缓解水气锥进，以及在俄克拉何马州、堪萨斯州和得克萨斯州裂天然缝碳酸盐岩油藏中钻水平井（见图2）。
Horizontal well technology is actually the development and progress of directional well and extended reach well technology. According to the curvature radius of the wellbore, horizontal wells can be divided into three types: long-radius horizontal wells, medium-radius horizontal wells and short-radius horizontal wells; they can be further divided into stepped and connected types according to their deep formation conditions; Horizontal wells, unconventional horizontal wells (Picture 3). The unconventional horizontal wells include: stepped horizontal wells, three-dimensional horizontal wells, multi-target horizontal wells, arched horizontal wells, paired horizontal wells, logging horizontal wells, connected horizontal wells, and multi-lateral horizontal wells.
In recent years, multilateral horizontal wells have developed rapidly as a key process for horizontal wells, and can be divided into fishbone type and tuning fork type according to their shape under the formation (see Pictures 4, 5, and 6).
Horizontal well technology is suitable for low-permeability oil layers, heavy oil reservoirs, multi-layer thin oil layers, fractured oil layers, complex fault-block reservoirs, and unconventional natural gas reservoirs such as coalbed methane, shale gas, and tight gas in old and new oil and gas fields. The advantages of horizontal wells are to encounter multiple production layers in different spatial positions from one main wellbore, increase the probability of reservoir drilling and effective area gas, provide multiple oil drainage modes, and control bottom water coning and delay edge water advance. It has become an important technology for oil and gas field development and is widely used in the world.
Horizontal well technology and equipment
Horizontal well technology is a technology that integrates wellbore trajectory design, drilling fluid design, sidetracking, completion, cementing and oil production. At present, international famous companies such as Schlumberger, Halliburton, Baker Hughes and Weatherford have developed their own patented technologies. Halliburton's core technology has a complete set of drilling, completion, production and branch re-entry supporting technologies and tools for horizontal wells, and its technology is in a leading position in the world. Table 1 shows the status of foreign horizontal well drilling technology.
Wellbore Trajectory Design The control of the horizontal well trajectory is the key to turn the horizontal well from design into reality. The ultimate goal of controlling the well trajectory is to accurately hit the target according to the design requirements. The geologically designed horizontal well target area is usually a cylindrical body in the pay zone with the horizontal well bore as the axis, and its normal section is mostly rectangular or circular. The key to control the target in the wellbore is to make the inclination, azimuth, vertical depth and displacement of each point of the trajectory within the range of design requirements. This is a completely different concept from the target in the ordinary directional well, that is, the concept of the target in the vector. . By developing and improving the accessories of downhole instruments, improving the configuration of measuring instruments, and researching new measurement techniques, three types of horizontal well trajectory measurement techniques, wired while drilling, wireless while drilling and combined while drilling, were formed in the early stage of horizontal well research. This technology also includes sidetracking horizontal well gyro directional measurement technology, horizontal well measurement accuracy analysis and error correction method, complete set of instrument testing, calibration and maintenance standards and process specifications to ensure the smooth running of the wired while drilling tool and prevent the instrument from falling off. Patented technology in technology and tools such as key locking device.
Drilling fluid design The particularity and unfavorable factors of the drilling fluid for horizontal wells have formed three types of mud systems and application processes: SN-1 polymer oil-in-water drilling fluid, SN-2 positively charged glue drilling fluid, and SN-3 low fluorescence drilling fluid . It can be used to determine the density of drilling fluid, rheological parameters and displacement of drilling fluid under different conditions, and solve the problems of cuttings carrying, wellbore stability, lubrication performance and production layer pollution in horizontal well drilling.
Completion method Open hole completion method. This is one of the simplest horizontal completions. That is, the technical casing is lowered to the top of the expected horizontal section, and the cement is cemented and sealed. Then change the first-grade bit to drill the horizontal well section to the design length and complete the well. Open-hole completion is mainly used in hard non-collapse formations such as carbonate rocks, especially in some vertical fracture formations, such as the Austin White Bad Formation in the United States. Slotted liner completion. The slotted liner is hung on the technical casing by the hanger, and the annular space outside the spacer is hanged by the packer. A centralizer should be added to the slotted liner to ensure that it is centered in the horizontal wellbore. At present, horizontal wells have developed into lateral wells and multi-bottom wells, and the completion methods of horizontal wells also mostly use slotted liner completion. Slotted liner completion is suitable for: natural fractured carbonate rock or hard sandstone reservoirs; single thick reservoirs or reservoirs that do not require interval separation; reservoirs with unstable wellbore and the possibility of wellbore collapse Layers; medium and coarse sand reservoirs with relatively loose lithology. The advantage of liner completion is that it can provide enough flow area, the reservoir is not polluted by cement slurry, can prevent the wellbore from collapsing, and the cost is relatively low.
Cementing and perforating completion methods. Cementing and perforating completion is currently the most widely used and most important completion method in the group. This kind of completion method can carry out staged stimulation and water injection operations, and is a very practical completion method. Including casing cementing perforation completion and liner cementing perforation completion.
Lined completions with an external packer (ECP). This completion method relies on the outer-pipe packer to implement interval separation, and can be operated and controlled by interval. The liner completion technology with external packer combines the external packer technology with drilling, slotted liner completion and wellbore cleaning technology. This technology can be used for the water layer or gas layer that needs to be sealed in the build-up section. For the horizontal oil layer with severe heterogeneity or the horizontal section crossing multiple layers, the casing outer packer can be used for multi-layer sealing to realize Collected or divided. For such reservoirs, drilling, slotted liner completion and wellbore cleaning technologies with multi-stage casing outer packers have been developed to realize the completion of one-time pipe string sealing of water or gas layers, slurry replacement, Pickling, etc.
Gravel Pack Completions Gravel pack completions are suitable for cemented and loose formations with severe sand production. In this completion method, the wire-wound screen is first lowered to the oil zone, and the ground-selected gravel is carried to the annular space between the wire-wound screen and the wellbore or the annular space between the wire-wound screen and the casing by circulating the filling fluid. , forming a gravel packing layer, blocking the flow of sand particles into the wellbore, protecting the well wall and preventing oil layer sand particles from entering the well. Figure 7 is a diagram of a horizontal well completion method.
Multilateral horizontal well in Saudi Aramco's Ghawar oilfield, the reservoir is interbedded with marine carbonate and gypsum. It is an intelligent completion string. The flow rate of each branch can be controlled. During the development of the Ghawar oilfield, if a branch wellbore exceeds 40% water content, the production of the branch wellbore will be shut down. Therefore, the intelligent completion string can realize layered production and alleviate interlayer production. contradiction. Improve development results. Figure 8 shows the horizontal multiple intelligent completion strings in Saudi Arabia.
Cementing technology Foam cement cementing technology. Foamed cement is formed by injecting foaming agent, foam stabilizer and nitrogen into cement slurry. Compared with ordinary cement, foamed cement has the following advantages: it generates higher dynamic flow shear stress during pumping, thereby improving its displacement to drilling fluid. It can avoid the damage caused by the shear stress of the cement shell caused by temperature and pressure; during the solidification process, with the volume contraction of the cement slurry and the continuous expansion of gas foaming, the internal pressure of the cement stone can be kept almost constant during the system transition stage. , the system can effectively control gas migration and formation fluid intrusion, has low compressive strength, and reduces the chance of artificially increasing fractures in hydraulic fracturing operations.
Double density flushing fluid, double density cement slurry cementing technology. Mobil Oil Company has applied a new horizontal well cementing process to improve the displacement efficiency, that is to use double-density flushing fluid and double-density cement slurry for horizontal well cementing. In highly deviated wells, the specific methods are as follows: (1) First, clean the wellbore. Circulate the dual-density flushing fluid (isolating fluid) downhole, and the number and time of circulation should ensure that the wellbore can be fully cleaned, so as to facilitate the solid production of the casing. (2) Run the production casing with the centralizer so that the casing is centered in the wellbore. (3) Pump the first cement spacer fluid into the annulus between the downhole casing and the well wall. After injecting a sufficient amount, stop the injection and let it automatically balance the pressure. The flushing fluid (isolation fluid) contains potassium chloride and chlorine. Sodium chloride, calcium chloride, zinc chloride, potassium bromide, sodium bromide, calcium bromide or zinc bromide, the density range is 1.0-1.4g/cm3 at room temperature. (4) The second type of cement spacer fluid is injected from the annulus. The spacer fluid contains diesel, kerosene, xylene, potassium chloride, sodium chloride or calcium chloride solution. The density is 0.1 smaller than that of the first type. The apparent viscosity of the two flushing fluids in the lower annulus should differ by 100 x 10-3pa•s. In this way, the second will remain on top of the first cementitious spacer fluid, cleaning the upper section while the first cleaning the lower section. (5) After a sufficient amount of circulation, stop the injection and allow the two isolation fluids to fully balance the pressure. And carry impurities, cycle cleaning wellbore. (6) The first type of cement slurry, namely conventional cement slurry, is injected into the annulus, and the density is higher than that of the spacer fluid. The amount of grout should be sufficient to fill the entire annulus. (7) The second low-density cement slurry or foamed cement slurry is injected into the annulus, so it is located above the first cement slurry after entering the well, filling the void not filled by the first cement slurry, effectively sealing the casing and strata.
双密度冲洗液、双密度水泥浆固井工艺技术。美孚石油公司应用了一种水平井固井新工艺提高顶替效率，即使用双密度冲洗液和双密度水泥浆进行水平井固井，该方法主要用于不能使用泡沐水泥浆进行紊流顶替的大斜度井中，具体方法如下：（1）首先清洗井眼。向井下循环双密度冲洗液（隔离液），循环数量和时间应保证能充分清洗干净井筒，以利于固生产套管。（2）下入带扶正器的生产套管，使套管在井眼中居中。（3）向井下套管和井壁间的环空泵入第一种水泥隔离液，注入足够量后，停止注入，让其自动进行压力平衡，冲洗液（隔离液）含氯化钾、氯化钠、氯化钙、氯化锌、溴化钾、溴化钠、溴化钙或溴化锌，室温下密度范围为1.0-1.4g/cm3。（4）从环空注入第二种水泥隔离液，隔离液含柴油、煤油、二甲苯、氯化钾、氯化钠或氯化钙溶液，密度比第一种小0.1，在井眼温度条件下环空中两种冲洗液的表观黏度应相差1OO x 10-3pa•s。这样，第二种就会保持在第一种水泥隔离液的上方，在第一种清洗下部井段时清洗上部井段。（5）循环足够量后，停止注入，并使两种隔离液充分进行压力平衡。并携带杂质、循环清洗井眼。（6）向环空注入第一种水泥浆，即常规水泥浆，密度比隔离液密度大。水泥浆量应足以充满整个环空。（7）向环空注入第二种低密度水泥浆或泡沫水泥浆，因此入井后位于第一种水泥浆的上方，填补了第一种水泥浆没有充填的空隙，有效地封隔套管和地层。
Tidal sand flow replacement process. When drilling multi-layer wells with different fracture pressures and pore pressures, no matter whether it is a depleted zone or a non-depleted zone, cementing in a long section of a highly deviated well requires reducing the equivalent circulation density and achieving reasonable replacement. It brings considerable difficulty to the construction. The research shows that in the double density cement slurry cementing. Such as keep the lower displacement. Limiting the flow rate on the wide side of the wellbore can better replace the fluid on the low side of the wellbore. Therefore, a new cementing technology has been developed abroad—low displacement and high density difference displacement technology, or cementing technology of tidal flow displacement. In order to maximize the density difference, the viscosity of the grout and spacer fluid should be as small as possible. Compared with graded cement injection and enlarged well diameter, the operating cost of this technology is lower, but the tidal flow displacement process cannot replace the turbulent flow and effective laminar flow replacement, it is only in the case that these two processes are not suitable for the wellbore conditions. as an alternative cementing method.
The technology is suitable for clastic rock, carbonatite, metamorphic rock, and magmatic rock reservoirs. Horizontal well technology is suitable for low-permeability oil layers, heavy oil reservoirs, multi-layer thin oil layers, fractured oil layers, complex fault-block reservoirs and coalbed methane development in new and old oilfields. A multi-lateral horizontal well in Tibet is a level 3 intelligent completion. The reservoir is a sandstone gas reservoir, and the mining target layer is two sandstone units: Uuayzah A and Uuayzah B. The middle is separated by siltstone units. Fig. 9 Multilateral horizontal well trajectory in Delta Oilfield, Saudi Arabia.
该技术适合于碎屑岩、碳酸岩、变质岩、岩浆岩储层。水平井技术适合于新老油田的低渗透油层、重油油藏、多层薄油层、裂缝性油层、复杂断块油藏以及开发煤层气，图9是沙特阿拉伯国家石油公司Delta油田的Uuayzah砂岩气藏的一口多分支水平井，为3级别智能完井。储层为砂岩气藏，开采目的层为2个砂岩单元：Uuayzah A和Uuayzah B。中间由粉砂岩单元分隔开来。图9沙特Delta油田多分支水平井轨迹。
Development Trend of Horizontal Well Technology
At present, foreign horizontal well drilling technology has been greatly improved through research in wellbore design, drilling tool configuration, drill bit, downhole power drilling tool, cabinet control, mud technology, and well control technology, which greatly reduces the technical risk of horizontal wells. , the horizontal wells in the United States have reached a technical success rate of 90%-95%. Now no matter large, medium, short or ultra-short curvature radius horizontal wells, the wellbore quality, drilling speed, drilling time, drilling cost and comprehensive benefits can be guaranteed. The drilling cost of horizontal wells can basically be controlled to the cost level of conventional vertical wells six years ago. Figure 10 is a short radius horizontal well.
Foreign horizontal well drilling technology is developing in the direction of integrated technology, that is, for the purpose of improving the success rate and comprehensive economic benefits, the comprehensive application of geology, geophysics, reservoir physics and engineering technology, etc. Comprehensive optimization of construction control. The application of its technology is also developing in a comprehensive direction. In recent years, the horizontal well drilling technology has been rapidly developed and put into practical application in large quantities. The technologies employed include steerable drilling assemblies, measurement-while-drilling systems, in-line drilling fluid motors, PDC bits, and underbalanced wells. Fig. 11 Schlumberger horizontal well multi-stage and layered fracturing technology.
Horizontal wells can be applied to clastic rock, carbonatite, metamorphic rock, and magmatic rock reservoirs. It is suitable for dead oil areas and attic oil caused by water cone, lens oil and gas reservoirs, thin oil and gas reservoirs and low-permeability oil reservoirs, high-viscosity and heavy oil reservoirs, reservoirs with different permeability requiring water flooding, and oil and gas with multiple groups of natural fractures reservoirs, high directional permeability reservoirs, tight sandstone oil and gas reservoirs, natural asphalt reservoirs, etc. Figure 12 shows the advanced horizontal well drilling process.
Horizontal wells in the United States have achieved a 90%-95% technical success rate. The horizontal well technology in developed countries is mature in Japan and Zhejiang. Horizontal well drilling technology is developing in the direction of integrated technology, that is, for the purpose of improving the success rate and comprehensive economic benefits, comprehensive application of geology, geophysics, reservoir physics and engineering technology, etc., the design and construction of horizontal wells for geological evaluation and oil and gas reservoir screening The control is comprehensively optimized. Figure 13 is a stepped horizontal well.
Horizontal wells are a new technology developed after directional wells, sidetracking and extended-reach wells, which can improve production speed and reduce development risks. level, high-efficiency development and sustainable development. Figure 14 shows the maturity of Halliburton's multi-lateral horizontal well technology.
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Horizontal well technology, development trend, high-efficiency exploration and development, directional well drilling technology, carbonate heavy oil reservoir, water and gas coning, radius of curvature, stepped horizontal well, three-dimensional horizontal well, low permeability reservoir, measurement technology, Drilling fluid design, wellbore trajectory design, gravel-packing completion, cementing technology, completion method, comprehensive economic benefits.
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