Step One: Preparation

Cementing a well is the procedure of developing and pumping cement into a wellbore. Although it is used for various reasons, cementing protects and seals the well. Very frequently, cementing is used to permanently block out water from penetrating the well. Cementing is also used to seal the annulus after the casing string has been run in the wellbore. In addition, cementing can be used to seal a lost circulation zone, or a specific area where there is a reduction or absence of flow inside the wellbore. When it comes to directional drilling, cementing is used to plug an existing well, in order to run a directional well from that point.

Cementing is performed when the cement slurries are placed into the well by pumps, displacing the drilling fluids that are still located in the well, and replacing them with the cement. The cement slurries flow to the bottom of the well through the casing, which will later be the pipe through which the hydrocarbons flow to the surface. From there it starts filling the space between the casing and the wellbore, and hardens. This permanently positions the casing in place and seals the wellbore so that outside materials cannot enter.

Preparing the Cement

When preparing a well for cementing, it’s very important to be certain of the amount of cement required for the job. This is done by measuring the diameter of the borehole along its depth. Also, to know the required properties of the cement is very essential before beginning any cementing operation. The proper set cement is good to be determined, including the density and viscosity of the material, before actually pumping the cement into the hole.

Special mixers are used to combine dry cement with water to create the wet cement that is also known as slurry. The cement used in the well cementing process is Portland cement, and it is calibrated with additives to form one of eight different API classes of cement. Each is employed for various situations.

Additives can include accelerators, which shorten the setting time required for the cement, as well as retarders, which do the opposite and make the cement setting time longer. In order to decrease or increase the density of the cement, lightweight and heavyweight additives are added. Additives can be added to transform the compressive strength of the cement, as well as flow properties and dehydration rates. Extenders can be used to expand the cement in an effort to reduce the cost of cementing, and antifoam additives can be added to prevent foaming inside the well. In order to plug lost circulation zones, bridging materials are also added. However, the critical part missing here is the management of numerous reports and search function.

Without an efficient lab database, we will face the following situations:

  1. Difficulty of designing cement slurries.
  2. Waste of resources to repeat similar tests.
  3. Lack of prove while job problems occur.
  4. Non-standard practices at various labs within a company.

To streamline the cement lab operation, PVI developed CEMLab:CEMLab - Cement Lab Data Management SoftwareThis software is an integrated database management application that:

  • Formulates slurries.
  • Calculates lab amounts for all ingredients, such as cement, dry and liquid additives, salts and water.
  • Generates weigh-up sheets.
  • Stores API test results.
  • Generates lab reports.

CEMLab, is a web based application that allows quick access to all of your slurry formulations and testing statuses from anywhere, at any time. The advanced search function allows users to find the formula and test quickly and brings the previous jobs to their screen in no time. It’s a great tool for preparation.

From The Pencil to Engineer Is Human

“Design is a way of life, a point of view. It involves the whole complex of visual communications: talent, creative ability, manual skill, and technical knowledge. Aesthetics and economics, technology and psychology are intrinsically related to the process. Design is the evolution of useful things.”

- Paul Rand, also known as the American Modernist.

When Paul Rand made this comment he was referring to two books written by Henry Petroski: The Pencil and To Engineer Is Human, in which basically he talks about how we can take everyday objects and turn them into better useful objects. For instance, how pins were turned into paper clips; how Styrofoam containers evolved; how Post-it Notes came about and even how a simple rock can be turned into something very useful. The list goes on and on, and it is easy to understand the connection between Petroski’s points of view with Rand’s ideas on invention, innovation and ingenuity.

When it comes to the evolution of useful things, the oil and gas industry has many examples, but just let’s take this moment to talk about one of them: cementing and its development process.

Cement fills and seals the annulus between the casing string and the drilled hole. It has three general purposes:

  • Zone isolation and segregation
  • Corrosion control
  • Formation stability and pipe strength improvement.

Cement forms a very strong and impermeable seal from a thin slurry. The properties of the cement slurry and its behavior depend on the components and the additives in the cement slurry.

The cement is produced from limestone and either clay or shale by being roasted at 2600 to 3000°F. This high temperature fuses the mixture into a material called clinker cement. Once the roasting step is done, the rough clinker product is ground to a size specified by the grade of the cement. The final size of the cement particles has a direct connection with how much water is required to make the slurry without producing an excess of water at the top of the cement or in pockets as the cement hardens.  However, not all cements, including those made from the same components, will have the same reaction when mixed with water. Generally, the differences are in the quality of the grind of the cement, impurities in the water and in the additives added during the cement manufacturing process.

The design and test of the slurry are essential parts of every cementing job and without an efficient lab database cementing companies can face many problems, but thanks to the evolution of technology PVI has developed the right tool for this: CEMLab (Cement Lab Data Management).

CEMLab - Cement Lab Data Management

Since its first release in the fall of 2012, CEMLab has evolved into a powerful web-integrated and highly functional software product. CEMLab formulates slurries, calculates the amount of all ingredients, generates weight-up sheets and lab reports and allows engineers to have quick access to all their slurry formulation, and testing statuses anytime from anywhere.  These are just a few of the many features that make up CEMLab. Just like from the books “The Pencil” to “To Engineer Is Human” we get to see how an object can be designed and turned into something more useful and successful, CEMLab has been turned into a useful, successful and sophisticated lab tool.