API RP 11S4:2002 pdf download
API RP 11S4:2002 pdf download.Recommended Practice for Sizing and Selection of Electric Submersible Pump Installations.
This performance is normally summarized in a pump performance curve (on either a single stage or multistage basis, commonly 100 stages or a specific number corresponding to the number of stages in a specific pump) that relates head (differential pressure), power required and mechanical efficiency to volumetric flow rate. These curves are often drawn showing flow rate to be the independent variable with head, power and efficiency being the dependent variable. This is actually only one way of looking at pump performance. For purposes of sizing, it is often useful to understand that in fact the relationship works in the other direction as well. The flow that a specific pump with a specific number of stages can provide depends on the differential pressure imposed on the pump.
The task in pump selection is to select the appropriate pump stage design for the desired pump flow rate and then select the appropriate number of stages to deliver the desired flow rate given the necessary head or differential pressure required to cause the well to flow at the desired flow rate.
Care should be taken to insure that in-situ pump flow rates and not stock tank rates are used to properly select stage type and number of stages.
A simple process for pump selection consists of the following steps:
Determine Stage Type
Depending on casing size and desired flow rate, there may be several possible pump stage types available for a given application. The pump stage type should normally be selected primary on the basis of which pump will be most efficient at the desired operating flow rate. As a rule, a pump should be selected such that the desired operating flow rate is as near as possible to the best efficiency point and, as a minimum, within the recommended operating range stipulated by the manufacturer. Although many pumps can be operated outside this range. the pump performance is best within this range and it is within this range that pumps are commonly tested by those adhering to API RP 11 S2 Recommended Practices for Suhmei:cihle Pump Testing.
Determine Number of Stages Required
Given a desired flow rate, Total Dynamic Head (TDH) required and pump stage type, read the head per stage corresponding to the desired pump flow rate. The number of stages required to achieve the desired flow rate will he the TDH divided by the head per stage at the desired pump flow rate the number of stages available may not exactly match that required. In most cases, this results in a very small error.
There are two configurations of pumps. In a floating stage design (most common), the impellers float axially on the shaft and the thrust of the individual impeller stage is absorbed on specially designed pads found on the diffuser. The fixed impeller or compression pump design has the impellers locked to the pump shaft in the axial direction and no thrust is absorbed by the impeller rubbing on the diffuser. In the compression pump, the thrust is transferred to the thrust bearing in the seal chamber. Please consult with your pump manufacturer to discuss which design is better for your application.
Determine Power Required by Pump
Read the horsepower per stage required by the pump from the curve at the desired pump flow rate. Calculate the total motor horsepower required to drive the pump by multiplying horsepower per stage by the number of stages and composite fluid specific gravity.
This information should he used in selecting a proper motor HP size.
6.2 LIMITATIONS AND CONSIDERATIONS
Besides hydraulic performance, several other physical limitations must be considered, even in simple applications.
6.2.1 Shaft Strength
The amount of horsepower that the pump shaft can transmit (torque at a given speed) should be checked to insure it is within acceptable limits stated in the manufacturer’s catalog. Exceeding this limitation can result in premature failure.
6.2.2 Housing Strength.
