¶ StrinGnosis® Overview
StrinGnosis® Overview is a tubular mechanics and wellbore heat transfer program designed to provide the well designer with an intuitive and accurate method for designing a wellbore, whether it is simple or complex. The program features a tubular design module coupled with a thermal simulator, enabling the designer to assess the effects of temperature on the design. The internal structure of StrinGnosis® is organized as depicted below.
The user interface of StrinGnosis® is organized as follows:
The tubular design module accommodates working stress design as well as reliability-based design using ISO databases or well designer-defined distributions for strength parameters, if they are available. The designer also has the ability to select his preferred units and to define custom databases for pipe, connections and grades. The thermal simulator has the ability to model a variety of producing and injection scenarios, as well as a Worst Case Discharge scenario, allowing the designer to simulate almost any conceivable thermal operation that may affect the wellbore.
Designing a wellbore using StrinGnosis® follows a logical progression similar to the well construction process itself.
- The wellbore is defined
- The casing program is described
- Applicable thermal processes simulated
- Loads assigned to each string
- Stresses calculated for each string
- Annular pressure build-up is analyzed where appropriate
- Wellhead movement is analyzed where appropriate
Defining the wellbore consists of specifying a basic description of the wellbore, wellbore trajectory and the formation characteristics (pore pressure, fracture pressure, undisturbed temperature, and any salt layers).
The casing program lists each tubular string that is to be run into the wellbore. The strings are defined by their function. The string's size, weight and grade are noted as well as the environment that defines the string's initial condition. A design basis is then chosen and appropriate safety factors selected. If a custom tubular, connection or grade is required, then it is described and selected. The designer has the ability to specify mixed strings in virtually any conceivable configuration.
The thermal simulator is capable of performingproduction, injection, and worst-case discharge thermal modeling of the wellbore for pseudo-transient conditions. A black oil fluid model is used to estimate the thermophysical properties of the fluids.
Loads are assigned to each tubular string using standardized templates. For loads the designer wishes to consider that don't fit one of the provided templates, a custom load utility is provided, where the designer has complete control over the pressure and temperature profiles.
Once all the loads have been entered, the program calculates the stress state for each string under each load condition specified. The Stress Results tab offers a wide variety of ways to view the results.
Once the designer has settled on a design, the trapped annuli can bedefined, if applicable, and a pressure build-up analysis performed. In the same manner, the uncemented sections of casing can be identified and wellhead movement calculated.
From nearly anywhere within StrinGnosis®, a number of features are available by right-clicking onthe display. So, when in doubt, right-click.