CSG Pump & Wellbore Options

Introduction

The TAHK: Coal Seam Gas (PSS) Forecast module has a variety of wellbore options as shown below:

1. Contract Rate - The ability to restrict production based on either a water or gas constraint. Default water for CSG

2. Flow Pressure Type - This lets the user select from any imported pressure such as tubing, Casing, PIP and more as discussed in Pressure Sources & Types of Pressures

3. Wellbore Model

Flow Pressure Type

In the example below, the user has imported Casing, Tubing, and Bottomhole Pressures - any which can be used with a wellbore model or without a wellbore model (i.e. no losses).

Constant Pressure

If a “Constant Pressure” is selected, then then the user is given the ability to input a single manual input to represent the majority of production data. In this example, the user has specified a flowing pressure of 250 psia and assumed it to be representative of BHP as no wellbore model has been chosen.

Using the Pump Option

In the TAHK: Coal Seam Gas (PSS) Forecast or KOLDUN: CSG Monte-Carlo modules, the “Pump Model“ is basically pump drawdown model in which the water rate (via the pump parameters) is manipulated/controlled.

In this model, the initial liquid level is specified by the user (The minimum value is zero which is 100% water filled wellbore). The user then specifies:

1. Initial Fluid Level - MEASURED FROM SURFACE

2. Pump Speed (drawdown by month in ft/month)

3. Pump Depth (ft)

4. Minimum head above the pump (ft)

The graphic below illustrates the basic inputs associated with the above options. As can be seen:

• Some layers can be in a gas column

• Some layers can be in a water column

The typical AFA GUI for the pump model is shown below. Note the USER can use any pressure (even measured BHP) for the wellhead pressure if they so desire (unusual, but allowable).