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;
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.
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.
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%
If the percentage of these additives is high, they will act as retarders instead of accelerators. Continue reading →
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
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 →
Cement squeeze and balanced cement plug are one of the most critical cement jobs on drilling sites. It is very critical to have the correct volume of cement and displacement in order to be successful in this operation. We create simple Excel spread sheets for both operations and these sheets are free for you to download. However, you need to carefully read the details below to understand the limitation of these two files because the calculations are based on specific criteria.
Cementing is very critical step of well construction. Bad cement job can lead to bad situations as well control, low productivity, gas channeling in annulus, etc. Therefore personnel in oilfield should learn and understand this topic. It is quite hard to find very good vdo training in the topic of oil well cementing but we finally find it. This VDO training is very excellent because it teaches all the basic with animations which absolutely helps learners fully understand this topic. Additionally, we add full VDO transcript so it will help some people who cannot catch all the wording in the VDO training. Please feel free to add comments and/or suggestions and we wish you would enjoy learning from this post.
Full VDO Transcript
Here is an overview of casing cemented in a well called primary cementing. The cement’s main jobs are to completely isolate or totally seal off all the oil, gas and water zones from the well bore and to bond the casing firmly to the wall of the whole. Here the crew has drilled the well to the casing point, the depth at which they will set and cement casing. The driller circulates drilling mud to clean the hole and to make sure the mud is in good condition. Then the crew pulls the drill string out of the hole. The next step in primary cementing is for the casing crew to run the casing into the well, one joint at the time. Notice at the bottom of the casing, the guide shoe and float collar. Also notice the centralizers and scratchers. The guide shoe guides the first joint of casing into the well bore. A valve in the float color lets the crew float the casing into the well to lessen the load on the rig’s hoisting system. Continue reading →