第四章
Drillstring Basics
钻具基础
Upon completion of this section you will be able to: 读完这一部分后，你可以 1、Explain how drill pipe grades define the yield strength and tensile strength of steel. 1、解释钻杆钢级是如何定义钢材的屈服强度和抗拉强度的； 2、Explain how drill pipe is classified. 2、解释钻杆是怎么分类的； 3、Calculate total yield strength for a specific grade/class of drill pipe. 3、计算特定钢级和类别钻杆的屈服强度； 4、Explain the effects of buoyancy on the drillstring. 4、解释浮力对钻具的影响； 5、Calculate the buoyed weight (or hookload) in a vertical hole. 5、计算直井中钻具的浮重（或称悬重）； 6、Explain the causes of varying hookload during the drilling process. 6、解释钻进过程中大钩悬重变化的原因； 7、Explain overpull and calculate the maximum permitted pull. 7、解释过提、计算最大许用上提力； 8、Calculate required BHA air weight for applications where drill pipe is to be run in compression. 8、计算在允许钻杆受压的钻井过程中，需要的井下钻具组合净重； 9、Calculate critical buckling force and explain the factors involved when running drill pipe in compression. 9、计算压曲临界力并解释压缩钻杆的钻井过程中的原理； 10、Explain causes and effects of sinusoidal and helical buckling. 10、解释正弦和螺旋弯曲的起因及影响因素；
Tubulars
管件
Introduction 介绍 Drill pipe and collars are designed to satisfy certain operational requirements. In general, downhole tubulars must have the capability to withstand the maximum expected hookload, torque, bending stresses, internal pressure, and external collapse pressure. Operational capabilities of different sizes and grades of drill pipe and collars are tabulated in the API RP 7G to assist the drilling engineer in selection of pipe and collars for a given drilling situation. Other concerns, such as the presence of H2S, must also be considered in the selection process. 钻杆和钻铤是为满足特定作业需求而设计的。总体来说，入井管件必须禁得 起预期的最大悬重、扭矩、弯曲力、内压力和外挤力。不同尺寸和钢级的钻杆和 钻铤的工作能力记录于 API 标准 RP 7G，以帮助钻井工程师在特定钻井条件下选 择钻杆和钻铤。在选择过程中，诸如存在 H2S 等具体情况也要加以考虑。 Drill Pipe Yield Strength and Tensile Strength 钻杆的屈服强度和抗拉强度 If drill pipe is stretched, it will initially go through a region of elastic deformation. In this region, if the stretching force is removed, the drill pipe will return to its original dimensions. The upper limit of this elastic deformation is called the Yield Strength, which can be measured in psi. Beyond this, there exists a region of plastic deformation. In this region, the drill pipe becomes permanently elongated, even when the stretching force is removed. The upper limit of plastic deformation is called the Tensile Strength. If the tensile strength is exceeded, the drill pipe will fail. Tension failures generally occur while pulling on stuck drill pipe. As the pull exceeds the yield strength, the metal distorts with a characteristic thinning in the weakest area of the drill pipe (or the smallest cross sectional area). If the pull is increased and exceeds the tensile strength, the drillstring will part. Such failures will normally occur near the top of the drillstring, because the top of the string is subjected to the upward
Grade E drill pipe has a lower yield strength in psi than the high strength drill pipe
grades, however once the yield strength is exceeded, it can withstand a greater
Drill Pipe Grades 钻杆钢级 There are four common grades of drill pipe which define the yield strength and tensile strength of the steel being used. 钻杆有 4 个常用钢级，定义了所用钢材的屈服强度和抗拉强度。
medium depth wells (10,000 to 15,000 feet).
E 级钻杆使用较低等级的钢材制造，这种钢材有时被称为“温和”金属，因为
它在单位面积上具有最低的屈服强度（psi）。温和金属通常定义为单位面积屈服
强度在 80,000psi 以下的金属。众所周知，E 级钻杆较高钢级的钻杆具有更小的
percentage of stretch or “strain” prior to parting. Lower grades of steel such as Grade
E are also more resistant to corrosion and cracking. Grade E has been utilized in
钢级
E
X-95
G-105
S-135
最小屈服强度（psi） 75000
95000
105000
135000
最小抗拉强度（psi） 100000
105000
115000
1450lower grade of steel, is sometimes referred to as “mild”
steel, because it has the lowest yield strength per unit area. As such, mild steel is
generally defined as steel with a yield strength of less than 80,000 psi. As can be seen,
pulling force as well as the downward weight of the drillstring. 如果钻杆受拉，起初，它会在一定拉力范围内发生弹性形变。在这个范围内，
如果拉力消失，钻杆能恢复原状。这个范围的上限称为屈服强度，可用 psi 衡量。 超过这个范围后，存在一个塑性形变范围。在这个范围内，钻杆被永久拉长，即 使拉力消失也不恢复。这个范围的上限称为抗拉强度，如果拉力超过抗拉强度， 钻杆会被拉断。钻杆被拉断的情况一般发生在上提被卡钻具的时候。如果拉力超 过屈服强度，钻杆最薄弱处（或最小截面积处）的金属会变细。如果拉力继续上 涨并超过抗拉强度，钻具会断裂。这样的断裂通常发生在钻具上部，因为管柱的 上部不但要承受向上的拉力，还要承受其下钻具的重量。
单位面积屈服强度（psi），然而，一旦拉力超过屈服强度，它在破断前，可以禁
受更大比率的拉力或“张力”。同样，像 E 级钻杆这样低等级的钢材对腐蚀和破裂 有更强的抵抗能力。E 级钻杆一般应用于中等深度的井（10,000ft ~ 15,000ft）。