Casing while drilling provides immediate benefits, saving both time and money by altering the steps needed for the drilling process. On top of this, the CwD system also provides a whole host of additional benefits. The benefits of casing while drilling can be summarized below;
Save Time and Cost
As mentioned in the introduction part, Basic Knowledge of Casing while Drilling (CwD), CwD is able to save operation time by cutting down flat time and reducing operational risk. When compared to conventional drilling, CwD can provide a time saving of between up to 37.5% of time spent on a well based on historical data from a field in Oman (136107-PA SPE Journal Paper – 2012). Continue reading
Casing while drilling (CwD) has been around for many years and it is one of proven technologies that can save both time and money. CwD is a process where a well is simultaneously drilled and cased; the casing is used for the drill string, and is rotated to the drill and cemented into the well at TD. One of the main benefits of this process is that it greatly cuts down on the tripping time needed to pull out the bottom hole assembly (BHA) and run the case- if not removing this need entirely. Therefore, the flat time is reduced, and the process is made more economically viable.
Figure 1- Casing while Drilling Operation (Courtesy of Weatherford)
As shown in Figure 2 below, which is an example of Casing while Drilling utilized in one of oilfields in Oman for drilling surface section; this process can save up to 37.5% of time spent on a well based on historical data.
Figure 2 – A comparison between conventional drilling and casing while drilling of one field in Oman (SPE 136107-PA ,SPE Journal Paper – 2012).
In order to properly design a completion, reservoir rock and fluid properties must be carefully taken into account because they directly influence on equipment selection. Reservoir properties (rock and fluid properties) which must be considered are as follows;
Low permeability formation may require fracturing operation to enhance production. The completion for tight formations must be able to withstand pumping pressure and allow fracking fluid and proppant to flow through.
Unconsolidated formations are required to complete a well with a sand control completion; thus, a well can be produced without any damage to downhole and surface equipment.
Reservoir pressure directly affects the pressure rating on all completions because all components must be able to work under reservoir condition. What’s more, formation pressure will affect how much flow of the well can produce.
High reservoir temperature will quickly degrade some components, especially elastomer, and this will result in well integrity issues due to pressure leakage. This is one of the critical concerns in selecting the right equipment to work under high temperature conditions. Continue reading
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
The Organization of the Petroleum Exporting Countries (OPEC) has agreed to cut supply by 1.2 million barrels per day (bpd) to 32.5 million barrels, the head of the organization announced.
Ahead of the official announcement, Bloomberg broke the news, quoting an unnamed delegate in Vienna. Crude prices soared more than 7 percent on the report. As of 16:29 GMT, Brent crude was trading at nearly $50 per barrel, while US crude benchmark WTI was above $48.
Calling the decision “historic,” the organization said the output cut would be in effect from January 1, 2017. The deal was reached after weeks of negotiations, as Saudi Arabia, Iraq and Iran fought for the very last barrel of production. This is the first coordinated cut from OPEC in eight years. Continue reading