考虑井筒摩阻的水平井产能预测(英文版)

1、abstracthorizontal well is a very important technology to explore oil field and to enhance recovery factor. horizontal well can increase the contact area in the pay zone and has attracted very wide attention in the world. horizontal well is superior to vertical well especially in low permeability re

2、servoir, thin pay zone, viscous oil, residual oil and so on. and it is very spread to explore oil field with horizontal well. horizontal wells production is reasonably designed and development index is accurately forecasted, and this has become an important problem to reach the development effect of

3、 oil fields forecast.the horizontal well can control the water rising velocity for small drawdown pressure and large drainage area and increase liquid producing capacity. it has become a new important technique of oil field development, releasing the old oil fields and enhanced oil recovery. in the

4、feasibility demonstration and optimization design of horizontal well development, the production prediction of horizontal well is an important basis for the decision-making project. there are a lot of kinds of methods to predict production of a horizontal well, according to the well completion metho

5、d, the type of oil reservoir, drainage area shape, pattern arrangement etc. it has different forms and application range.in this paper, joshis formula is systematically introduced and revised considering the friction within the borehole. the revised production, comparing with the original production

6、, shows that the friction within the borehole has great influences on the production of horizontal well. and it has very important significance on productivity prediction of horizontal well.key words：horizontal well；friction；production；predictioncontentschapter 1 introduction11.1 horizontal well dri

7、lling technology development situation11.2 definition of horizontal well11.3 classification and characteristics of horizontal well21.4 application of horizontal well41.5 production prediction method of horizontal well introduction7chapter 2 production prediction method of horizontal well112.1 produc

8、tion prediction in different drainage region112.2 production prediction under different completion mechanism132.3 production prediction in different reservoir172.4 production prediction of different horizontal well patterns192.5 production prediction of multi-branched horizontal wells23chapter 3 pro

9、duction of horizontal well influenced by friction within the borehole253.1 derivation of joshis formula253.2 joshis formula considering friction within the borehole283.3 application examples30conclusions34references35acknowledgements36chapter 1 introduction1.1 horizontal well drilling technology dev

10、elopment situation in 1863，swiss engineer first proposed the suggestions of horizontal drilling；in 1870, sweden and the united states developed the measurement instrument of space position in the borehole .in 1888 russia also designed the well bore survey instrumentin 1929, the us drilled a few mete

11、rs long horizontal drain-hole in california,in the 30s, the united states began with flexible combination drilling string in vertical well drilling in small curvature radius of horizontal wells branch boreholein 1954，the soviet drilled the first extended reach horizontal wellin 1964-1965，china succe

12、ssfully drilled two horizontal wellssince the 80 s，with the advanced measuring instrument, the long life motor and new pdc bit technology development，horizontal well drilling massively developed in high speed. our country horizontal well drilling has also made great development since the 90 ssheng l

13、i oilfield has completed a various types of horizontal wells more than 100horizontal well drilling level and speed constantly improves in high speed 1.2 definition of horizontal well horizontal well is a directional well with the inclination up to nearly 90 degree (generally more than 85 degree)，and

14、 maintains a certain length or nearly standard horizontal section. since the 80 s in horizontal well drilling technology continuing to mature is mainly attributed to the directional drilling technology，it is the great progress of directional drilling technology development。in the geological applicat

15、ion，laminated formation, density sandstone containing gas layer, lens-type reservoir, low permeability reservoir, the water flooding reservoir, gas cap flooding reservoir, gravity flooding reservoir, vertical fractured reservoir, double pore reservoir, double permeability reservoir, thin layer and f

16、luid excreted not free and so on, using horizontal well drilling has the advantagein oilfield development, the horizontal well obtains the development advantage by optimizing the well completion technology, the horizontal well can improve the well bore connected area and the drill thickness in reser

17、voir, reduce the pressure difference at the bottom of a well, control the speed of the flow into the bottom，to prevent the sand movement，oil and gas communication between zones，water and gas coning, fluid bearing in tubing etc. in enhanced oil recovery, the horizontal well can increase the fluid flo

18、oding speed, and more evenly displace oil, and reduce the risk of polymer decompositionthe horizontal well has so many applications field that vertical well can be incomparable.1.3 classification and characteristics of horizontal wellat present，according to the horizontal section characteristics and

19、 functions，horizontal wells can be divided into ladder horizontal wells，branch horizontal wells，herringbone horizontal wells，multiple horizontal wells，double horizontal well，long horizontal section horizontal wells etc.according to curvature radius of angle buildup interval，the horizontal wells can

20、be divided into four types: long radius, medium radius, short radius horizontal wells（fig.1-1）and ultra short horizontal wells。 small curvature radius medium curvature radius normal curvature radiusfig.1-1 profile map of different radius horizontal well1.3.1 long radius horizontal well systemborehol

21、e curvature is less than 6 / 30 m of horizontal wells. horizontal wells drilling technology has enter a new historical period，but long curvature radius system still has its application field，many horizontal wells with long radius system successfully have been drilled out in the explored and proved o

22、ilfield area. for offshore drilling platform，big span or comprehensive consideration of the obstacles of position and the oil field under a city etc., it is best to use the long radius.usually，long curvature radius horizontal wells is with normal down hole tool. kick off points of this type of horiz

23、ontal wells are closer the well head. as the curvature radius is big, it can achieve a large horizontal displacement.1.3.2 medium radius horizontal well system in a broad sense, this horizontal well drilling system is based on the ultimate value of complex stress of drill string bend and torsion giv

24、en by the api for effective drilling operation. after practicing，the biggest actual severity of dog legs in rotary drilling is 20/ 100ft and in directional drilling is 30/100ft。the applicable scope of medium radius horizontal wells system is very large. and in the north sea, the gulf of mexico, los

25、angeles and northern alaska operation has been a huge success. it was successfully applied to solve the oil development of water coning, gas coning, and organic reef and crack formation.1.3.3 short radius horizontal well systemthe short curvature radius horizontal well drilling system is using flexi

26、bility or hinge tools to drill a dog leg rate in the scope of 60 300 / 30 m. from the economic speaking, the short curvature radius system comparing with the other way for a variety of reasons is difficult to carry out operations. for example, the horizontal section length of short radius system is

27、just nearly 10% to 30% of long radius and medium system at present. due to the low rate of penetration, the unit cost of short radius is 10 times of long radius and medium system. although in the same intended interval, the total cost of completing a short radius horizontal wells may be the same to

28、long radius and medium radius system, but its horizontal section length much smaller, so its recovery ratio is certainly not as good as in long radius and medium radius horizontal wells.1.3.4 ultra short radius horizontal well systema new method of horizontal wells are ultra short radius drilling sy

29、stemthe ultra short radius horizontal well is 1m4m curvature radius from vertical to horizontal. on one hand, it is the high pressure liquid injection out a horizontal bore hole, its mutative curvature radius is only a few inches to a foot or so. now using this system to drill horizontal section len

30、gth of a horizontal well is limited within 2000ft.1.4 application of horizontal well1.4.1 natural vertical fractureswith the same to limestone, natural vertical fractures crossing the reservoir for horizontal wells provide desired application conditions , this type of well bore can make production a

31、dd up to 4 20 times. in the vertical fractures reservoir, oil and gas are completely in fractures, nonproductive formation between the fractures is of 6 60 m thickness, so the vertical well may drill only to one productive layer, even one productive layer also cant be drilled, and horizontal wells i

32、ntersecting vertically pay formation can drill through several pay formation fractures, so that the production is much higher than vertical wells.1.4.2 water coning and gas coning（1）water coning: for water drive reservoir, especially when oil viscosity is much higher than water , vertical wells may

33、meet the problem of water coning. in this situation, the wells will turn out oil belt with water. the horizontal well can kick off on the top and middle of the reservoir, and then in the productive zone drill a certain length of horizontal section. the horizontal well not only reduce the possibility

34、 of water coning, and each of unit length for pressure drop of oil than vertical wells for oil production is lower, water breakthrough and sanding problem is less than vertical wells.（2）gas coning: because the viscosity of the natural gas is far lower than the oil, gas coning than water coning usual

35、ly is more serious. if gas coning cant be controlled, oil reservoir must inject gas to maintain production, or pressure will drop prematurely. the horizontal well bore is all in oil sands, so it can help to avoid gas coning problem and control the recovery. the pressure gradient of gas coning will n

36、ot be too high.the horizontal wells success in reducing the water coning and gas coning and other harmful effects. therefore, the horizontal wells can significantly improve the production.1.4.3 low permeability formationin low permeability reservoir, due to the low productivity, one of the methods o

37、f improving fluid flow is fracturing, but, more attractive way to solve it is horizontal well drilling. a horizontal well can greatly increase oil drainage area.1.4.4 thin formationfor oil sheet, drilling a horizontal well between up and down boundaries in the reservoir can greatly increase the cont

38、act area between petroleum reservoir and wells. 1.4.5 irregular formationhorizontal well drilling has been successfully applied in the irregular reservoir. this oil formation are linked and exist alone, the earthquake logging can also be difficult to measure accurately the position, so the vertical

39、wells or conventional directional well are hard to drill to such reservoir. however，short radius horizontal well can kick off on the position closing to the reservoir of existing vertical wells and avoid possible water coning and gas coning problem.1.4.6 heavy oil pay formationin the heavy oil produ

40、ction layer, horizontal well drilling can increase production. horizontal wells across the reservoir not only can be as a production well but also be used as a water injection well.1.4.7 enhanced oil recoverythe horizontal well can also enhance oil recovery. in steam injection case, the low injectio

41、n rate of vertical wells often presents poor quantity of heat balance, a part of the energy consume in the ground pipelines, oil wells and heat loss of adjacent formation, however, the horizontal well can improve influx, directly heat up more oil volume. it will improve heat balance in significant m

42、easure. in addition, in order to effectively inject miscible plug (carbon dioxide gas, liquefied petroleum gas, surface active agent), it must spread longer distance. in this case horizontal oil drainage is undoubtedly an improvement.1.4.8 multi-branched horizontal wellmulti-branched horizontal well

43、 be defined as a kind of horizontal well that drills two or more branch boreholes (secondary borehole) into the hydrocarbon reservoir at the bottom of original hole (vertical well, horizontal wells, deflected well), and even drills a three-level borehole from secondary borehole. branch borehole can

44、be deflected well, horizontal well or wave-mode branch borehole. multi-branched horizontal well can get the maximum total displacement and drill across sets of hydrocarbon reservoir in different depth in the same or different directions, especially through the branch sidetrack can extract the old we

45、lls and even the dead oil area of abandoned wells. so it can greatly increase the discharge area of hydrocarbon reservoir and extend the life of oil field, and then bring abandoned wells back to life, improve the oil (gas) oil recovery, so as to improve the oil (gas) well production.multi-branched h

46、orizontal well mainly has two different types: one is biotope multi-branched horizontal well, and it can be seen as the plane branch situations; the other is layering multi-branched horizontal well. according to the structure of branch well, mainly divided into: multi-branched well, bifurcate well,

47、a few branch boreholes of horizontal wells and a few branch boreholes of vertical wells , face to face double branch boreholes and overlapping branch wells(figure 1-2). fig. 1-2 classification of multi-branched horizontal wellmulti-branched horizontal well can greatly improve the efficiency, reduce

48、the production cost of oil and gas well, improve per well production, achieve high capacity using less wells, and also improve the ultimate recovery. the main advantages of multi-branched horizontal well are as follows:(1) increase the contact area of well and reservoir and discharge oil area, impro

49、ve dynamic flow profile of reservoir, reduce coning effect, improve the drainage efficiency, and enhance oil recovery.(2)multi-branched horizontal well can be applied in a variety of economic reservoir exploitation, effectively explore heavy oil reservoirs, naturally fractured density reservoir and

50、heterogeneous reservoir. it can effectively develop complex geological structure, isolated and scattered small faulted block and reservoir. the oil field of economic benefit closing to the limit can reduce the development costs by drilling multi-branched horizontal well and make it into an economic,

51、 effective and exploitable oilfield.(3) multi-branched horizontal well can be drilled in the different target layer that needs to adjust or in the same layer in a main borehole or an available old well, in order to reduce the inefficient interval and reduce the cost in addition.(4)multi-branched hor

52、izontal well can improve overall economic efficiency of oilfield development. from the main borehole or old well drilling branch borehole, it increases the ratio of effective drilling footage and total drilling footage, so as to reduce the cost.(5) using multi-branched horizontal well to develop oil

53、field, due to the number of wells decreasing, it can reduce the ground engineering and management costs on land, the number of platform or the number of well slots in the sea, cut down the platform size, or use one-level light platform, etc., thus it can significantly improve the economic benefits.

54、1.5 production prediction method of horizontal well introduction the research of production prediction method of horizontal well started in the 1950s. soviet scholars first published the calculation formula of production prediction method of horizontal well in the 1958. in 1964 the other soviet scho

55、lar in his column systematically summarized the development history and production principle of horizontal well, and this paper presents a steady production calculation equation of horizontal well. these work marked the beginning of analysis theory and analysis method of horizontal well productivity

56、.1.5.1 foreign production prediction of horizontal well giger using hydropower similar theory deduced the productivity ratio equation of horizontal wells and vertical wells in homogeneous and isotropic reservoir, at the same time the anisotropy seen as affected by homogeneity was introduced to the p

57、roductivity ratio equations, then obtained the productivity ratio equation of horizontal wells and vertical wells affected by permeability anisotropy. joshi turned the three-dimensional fluid flow problem of horizontal wells into the two-dimensional fluid flow problem in horizontal and vertical plane and firstly deduced the steady-state production equation of horizontal well in homogeneous isotropic reservoir taking advantage of potential theory. then he fixed the isotropic production equ