Category Archives: Oil Well Cementing

What are Cementing Additives to Enhance Cement Properties

By | |
Leave a comment

Cementing in the oil and gas industry involves a meticulous process, and cementing additives play a crucial role in fine-tuning the properties of cement slurries. These additives are carefully selected to control slurry density, rheology (flow behavior), fluid loss, and to impart specialized characteristics for effective cement placement in diverse downhole conditions. Let’s explore the various categories of additives used in cementing:

1. Accelerators: Accelerators are chemicals employed to expedite the thickening process of a cement slurry and enhance early strength development. Typically used in conductor and surface casing applications to reduce waiting-on-cement time (WOC), common accelerators include calcium chloride (CaCl2), sodium chloride (NaCl), and seawater. Continue reading →

Classes of Oil Well Cement Used in Petroleum Industry

By | |
Leave a comment

Oil well cement adheres to API Specification 10 and is categorized into eight classes, labeled A to H, based on its specific properties. Among these, Class G and Class H serve as foundational well cements that can be employed alongside accelerators and retarders to accommodate a broad spectrum of well depths and temperature conditions. One notable distinction between these two classes lies in their particle size, with Class H being notably coarser than Class G.

Continue reading →

Important Casing Accessories Fitted to the Casing String to Improve Cement Quality

By | |
2 Comments

A number of components are fitted to the casing string to enable it to be cemented in place. In order to successfully cement each casing string, casing accessories should be installed and the necessary components are listed below;

Float Shoe

A float shoe is a short and rounded shape component with non-return value inside which is installed at the end of the casing. The advantages of a float shoe are as follows;

  • Prevent mud flowing back while running casing and prevent cement from outside U-tubing back into casing due to unbalanced conditions while performing cementing operation.
  • Help running casing to the well. The round shape of a float shoe prevents a casing string from hanging up and guiding a string into a wellbore. Some float shoes are made of high strength drillable material and can be used to reciprocate and rotate to pass any obstructions in a wellbore.
Float Shoe

Float Shoe

Continue reading →

Oil Well Cement Additives

By | |
2 Comments

Most oil well cement slurries will be added to some additives in order to modify cement properties so cement operation can be properly performed. In this article, it will cover some of important cement additives in general terms so that it will help you understand the basic function of each additive.

oilwell-cement-addtives

Accelerators

Accelerators are added to shorten the time for cement to properly set and it will reduce rig time while waiting on the cement (WOC). Accelerators are crucial in shallow depths where bottom temperature is low. In the deeper section, it may not require an accelerator, because the well is hot enough and the thickening time will be normal. The WOC time is generally based on the time required to obtain 500 psi compressive strength of the cement.

Chemical used as accelerators are as follows;

  • Calcium chloride 1.5 – 2.0 %
  • Sodium chloride 2.0 – 2.5%
  • Sea water

If the percentage of these additives is high, they will act as retarders instead of accelerators. Continue reading →

Cement Calculator (Metric Unit) Excel Spreadsheet

By | | , ,
5 Comments

Jonathan Lukye who is a supervisor from Sanjel in Estevan, Saskatchewan, Canada shares his cement Excel spreadsheet. He has been working on a Metric Cement Calculator in Excel. In the Excel spreadsheet, it contains; Surface Cement, Intermediate / Production, Liner, Retainer, Plugs, Deviated Hole and Squeeze.

This is the latest version as of 14 September 2016.

Updated features of this version

  • Remove the code has made the calculator’s footprint smaller and faster on Smart Devices.
  • Make the file smaller
  • Fix some calculation errors
  • Fix cement plug calculation

Balaced-cement-excel

The Surface, Intermediate and Liner Worksheets are “automatic” where there is no need for a handbook for factors as the sheet calculates them.  They also print out the job procedure for that sheet. Continue reading →