The well planning process starts from geologists and reservoir engineers who decide the best place for the wellbore. They may only need to determine a single target, which will often be a tolerance of about 330 ft (100 m) around a certain target point. In this case, the angle at which the well enters the target can have various degree of deviation from the plan since a plan requires to hit only one target. On the other hand, it might be necessary for the well to penetrate multiple targets, with the final target being increasingly complex. This requires what is known as “geosteering”, a process which will be discussed later in the directional drilling series. The drilling engineer therefore needs to examine potential surface locations (if more than one is available) and design a well path which meets all necessary target requirements at the lowest possible cost. Cost can be minimized most effectively when there is a certain degree of flexibility when it comes to the surface location.
Mechanical properties of material are one of the most important basic concepts in a well design and this section will briefly discuss about key mechanical properties and their applications. Furthermore, there is a discussion about effect of corrosion on the mechanical performance of load carrying components.
Mechanical Properties of Material
Basic mechanical properties are as follows;
Hardness is a resistance of materials to permanent deformation and is sometimes referred to a resistance to abrasion or scratching. The greater of the hardness, the harder it is for the materials to deform. The application of hardness is to inspect if materials have been properly treated during a heat treatment process. The comparison between the actual hardness and the standard hardness of materials will show whether the current batch of material is proper and suitable for use or not.
Strength of material is an ability to work within a load without failure of the material. Tensile and yield strength are critical properties in terms of material strength.
Tensile strength or ultimate tensile strength is the maximum stress on an engineering stress-strain curve. At this point, materials are plastically deformed but they may not be broken apart yet depending on types of materials. Continue reading →
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 →
The well is in an underbalanced condition while pulling out of hole. You can see in the video below that the fluid is flowing up from the drill pipe side. It is such very important to understand the condition of the well and have the plan to deal with it.
These are some thought about this situation from our member in the Facebook fanpage.
Hossam Hamza – Looks like it was failed balanced cement plug job, I see long cement chiksan line on rig floor and circulating head connected with low TQ valve above 1 joint DP in mouse hole, the back flow due to over displacement. Is my guess right???? Continue reading →
One of my friends shares this slide, An Introduction to Oil & Gas Drilling and Well Operations. This slide is the educational material from the IOM3 Oil and Gas Division, UK (http://www.iom3.org/). This is show all the basic of drilling and well operation in very simple language term. Additionally, there are several images which help explain content in this document clearly. This is a very good document when you try to explain overall drilling and well operation to new team members who don’t have much oilfield experience. The subjects covered in this presentation are as follow;
•Why we drill wells
•The well life cycle
−Well design and construction
−Pipe handling and the drill string
−Drilling and drill bits
−Cementing (including plugging and abandonment)
•Well testing and evaluation