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. [click to continue…]
1029.4 is used in several calculations in the oilfield and we’ve been asked about what is 1029.4, how it comes from, why it needs to be this figureso in this article, we will show you how 1029.4 comes from.
First of all, we would like to give someone about the background of this figure. The 1029.4 is widely used for capacity calculations. The following equations utilizing 1029.4 are listed below; [click to continue…]
We learn from the past in order to prevent the bad incidents to be happened. This time we would like to discuss about Sedco 135F – IXTOC I Blowout and Oil Spill. The Sedco 135F was perforating and drilling the IXTOC I well in 1979 for PEMEX, which is a petroleum company in Mexico owned by the state at the time when the well underwent an eruption. Through a drilling, the well had been dug up to 3.6 km with the 9-5/8″ casing set at 3.6 km. It has been vindicated by various studies that there was a failure in mud circulation (essentially mud is a massive and heavy weighted drilling fluid which is utilized as a lubricant for the drill bit, helps in cleaning the drilled rock from hole and present a column of hydrostatic pressure as a prevention from influxes), hence a consensus was reached that it is the best to pull the drill string & plug the well. The absence of mud column’s hydrostatic pressure triggered an unconstrained and liberal circulation of oil & gas to the surface, and this was what happened when the crew was working with drillstring’s lower part. The BOP was shut on the pipe however it was unable to chop the chunky drill collars, permitting oil and gas to come up to the surface where it burned and inflamed the Sedco 135F. The rig broke down and drowned on top of the wellhead space on the seabed, cluttering the seabed with debris like the rig’s derrick & 3000m of pipe.
One application of the rig tong is to use to make up connection. The question is asked about how to get the right torque value to the connection if you use the rig tong because you will not see the torque value on the gauge.
This article will describe how to determine the correct force applied to get the correct torque value when you use the rig tong to make up the connection.
Bullheadingis one of the well control methods which may be utilized in some occasions in order to control the well. Concept of bullheading is to pump kicks back into formations by using kill weight fluid. People usually use this method when normal circulation is impossible and volumetric method is not feasible to perform.
When May You Consider Using the Bullheading Well Control Method?
When the kick size is very big so you may not be able to control the excessive volume coming to the surface.
When you need to reduce surface pressure in order to start further well control operations.
When there is a possibility to exceed surface pressure and volume gas on the surface if the conventional methods (drillers’ method, wait and weight and volumetric) are performed.
When there is no pipe in the hole while taking influx.
The influx contains high level of H2S which can cause safety of personnel on the rig.
When there is no feasible way to strip back to the bottom in order to kill in the flux below.
There are several articles discussing about casing design and we would like to share you this excellent VDO training in this topic “Oil & Gas Well Casing”. This VDO contains the basic over view of casing starting from surface to production section. You will see nice illustrations which help you get clearer picture on this topic and we also add full VDO transcripts to provide assistance to some learners who cannot catch the content in this VDO clearly.
Oil & Gas Well Casing – VDO Transcript
By the time the crew drills the well to depth, it usually has several strings of casing in it. These strings are called conductor casing, surface casing, intermediate casing and production casing.
Notice that cased well looks something like a telescope pulled out of full-length but it is as the crew drills the well deeper, the size of the whole and the size of the casing gets smaller in diameter. Almost always, the drilling contractor cannot begin drilling at the surface and go all the way to total depth in one step.
Petrobras P-36 – This incident cost several million us dollars and it’s worthy to learn from it. One of the biggest global floating semi-submersible oil platforms Petrobras 36 (P-36), which was owned by Petrobras, an oil company in Brazil with its base of operations at Rio De Janeiro was destroyed after 20th March 2011 when it sunk. The platform was then approximately valued at US$350 million. Its current value is US$466 million. Constructed and erected as a drilling rig in the year 1995, at the Fincantieri shipyard (Genoa, Italy), was owned by SocietàArmamentoNaviAppoggioS.p.A. The rig, which was a good 33,000 tonnes was transformed to the biggest global oil production platform by Davie Industry, Levis, Canada. P-36, which was functioning for Petrobras, about 130 kms off the coast of Brazil on the Roncador Oil Field daily generated approximately 84,000 barrels (13,400 m3) of crude oil. P-36 was substituted by a chartered vessel from SBM Offshore, FPSO-Brasil, which is in a lease contract with Petrobras since Dec 2002. [click to continue…]
From the previous article, you’ve learnt about overall of casing design process and in this article we are going to discuss about how to select casing setting depth. The selection of casing string and setting depth is based on formation pore pressure and fracture gradient of the well.
For the casing setting depth determination, pore pressure and fracture gradient are normally described in PPG (Figure 1).
Figure 1 – Pore Pressure and Fracture Pressure Plot