---
id: po.wb.rp.tapered-rod-string
title: Tapered Rod String Analysis
category: Production
requires:
  - po-addin
tags:
  - rod-pump
  - sucker-rod
  - rod-string
  - tapered
  - stress
  - stretch
  - polished-rod-load
  - artificial-lift
---

# Tapered Rod String Analysis

## Description

Static loads, stress and stretch for a sucker rod string made of up to four rod sizes. Each taper
is one row, top taper first; unused rows are left blank. For each taper it returns the rod area,
the weight in air and in the well fluid, the load and stress at the top of the taper and the
taper's stretch. For the string it returns the static peak and minimum polished rod loads, the
highest rod stress and the total stretch.

The fluid load acts over the net lift, the depth from surface to the fluid level in the annulus: the
pump depth (the length of the rod string) less the fluid level above the pump. The fluid gradient is
0.433 psi/ft × SG, so specific gravity is the only fluid input. The top of each taper carries the
fluid load plus the buoyant weight of that taper and every taper below it. Stretch counts the
fluid load, the taper's own weight and the weight of the tapers below, with rod weights taken in
air as `PO.RP.Rod.Stretch.RodWeight` does, so a string of one rod size gives the single-size
answer. No API RP 11L dynamic factors and no fatigue check.

## Inputs

Named cells you can edit — every result recalculates from them.

| Name | Description | Default | Unit |
|---|---|---|---|
| `TRS_Dp` | Plunger diameter | 1.5 | in |
| `TRS_Hsub` | Fluid level above pump (submergence) | 500 | ft |
| `TRS_SG` | Fluid specific gravity | 0.85 | — |
| `TRS_Diameters` | Rod diameter of each taper, top first (four rows) | 0.875, 0.75, blank, blank | in |
| `TRS_Lengths` | Length of each taper, top first (four rows) | 2000, 3000, blank, blank | ft |

Calculated from them: `TRS_Depth` (pump depth, the rod string length), `TRS_NetLift` (net lift),
`TRS_G` (fluid gradient) and `TRS_Fo` (fluid load on the plunger).

## Sheets

- `Guide`
- `Rod String`

## Functions used

`PO.RP.Load.FluidLoad`, `PO.RP.Load.MPRL.Simple`, `PO.RP.Load.PPRL.Simple`, `PO.RP.Rod.Area`,
`PO.RP.Rod.MaxStress`, `PO.RP.Rod.Stretch.FluidLoad`, `PO.RP.Rod.Stretch.RodWeight`,
`PO.RP.Rod.Wair`, `PO.RP.Rod.Wbuoy`