Format: MS WORD  |  Chapter: 1-5  |  Pages: 75  |  418 Users found this project useful  |  Price ₦3,000





As the demand for petroleum resources increases, drilling of oil and gas wells are often carried out in challenging and hostile environments. Among the top ten drilling challenges facing the oil and gas industry today is the problem of lost circulation. Major progress has been made to understand this problem and how to combat it. However, most of the products and guidelines available for combating lost circulation are often biased towards advertisement for a particular service company. The purpose of this study is to develop practical guidelines that are general and not biased towards a particular service company product and which will also serve as a quick reference guide for lost circulation prevention and control at the well-site for drilling personnel.




Lost circulation is a common drilling problem especially in highly permeable formations, depleted reservoirs, and fractured or cavernous formations. The range of lost circulation problems begin in the shallow, unconsolidated formations and extend into the well-consolidated formations that are fractured by the hydrostatic head imposed by the drilling mud (Moore, 1986). It can then be defined as the reduced or total absence of fluid flow up the formation-casing or casing-tubing annulus when fluid is pumped down the drill pipe or casing. The industry spends millions of dollars every year to combat lost circulation and its associated detrimental effects such as loss of rig time, stuck pipe, blow-outs, and less frequently, the abandonment of expensive wells. Two conditions are both necessary for lost circulation to occur down hole: 1) the pressure in the well bore must exceed the pore pressure and 2) there must be a flow pathway for the losses to occur (Osisanya, 2011). Sub-surface pathways that cause, or lead to, lost circulation can be broadly classified as follows:

Induced or created fractures (fast tripping or underground blow-outs) Cavernous formations (crevices and channels)

Unconsolidated or highly permeable formations

Natural fractures present in the rock formations (including non-sealing faults)

The rate of losses is indicative of the lost pathways and can also give the treatment method to be used to combat the losses. The severity of lost circulation can be grouped into the following categories (Abbas et al. 2004):

Seepage losses: up to 10 bbl/hr lost while circulating

Partial losses: 10 – 500 bbl/hr lost while circulating

Severe losses: more than 500 bbl/hr lost while circulating

Total losses: no fluid comes out of the annulus

Circulation may be lost even when fluid densities are within the customary safety-margin; less dense than the fracture density of the formation. Stopping circulation losses before they get out of control is crucial for safe and economically rewarding operations (Abbas et al. 2004). According to Ivan and Bruton (2003), “Deepwater drilling has brought loss circulation control to a more critical level as it involves narrow pore-pressure/fracture-gradient windows, cold drilling fluid temperatures, high equivalent circulating densities (ECDs), high cost-per-barrel of synthetic-based fluids (SBM) and a high cost for rig time/non-productive time (NPT).” The reduction of the fracture pressure gradient in the deeper water is mainly due to the low stress regime as a result of the reduction in the overburden pressure gradient. Also, drilling through sub-salt zones poses a challenge to the operator because of the problem of lost circulation encountered in these zones. These wells have shear zones above and below the salt formations and also narrow margins between the pore and fracture pressure and hence these wells tend to register severe losses in circulation.


Lost circulation is a broad subject and several studies and measures have been introduced in the industry to combat it. For example, Moore, (1986) noted that in shallow, unconsolidated formations where the drilling fluid may flow easily into the formation, the most common method used to combat lost circulation is to thicken the mud. This may be done in fresh water muds by adding flocculating agents such as lime or cement. He also stated that in areas such as below surface casing in normal-pressure formations where natural fractures are common, the most common method used to combat lost circulation is to drill without fluid returns to the surface. The purpose is to remove the generated cuttings from the hole and deposit them at the lost circulation zone. However, this practice requires large volumes of water and close supervision as there is the possibility of encountering high drill-string torque and drag.

Current research on lost circulation has been focused on the use of Lost Circulation Materials (LCMs), especially chemical formulations which have been proven to be more effective. Hamburger et al. (1983) of Exxon Production Research Company developed a Shear-thickening Fluid (STF) which was tested successfully in 10 different wells that experienced severe lost circulation. A STF is a multi-component system composed of water-swellable material (usually clay) dispersed in an oil-external emulsion. The emulsion consists of liquid oil, an oil-soluble surfactant, and aqueous-phase droplets containing dissolved polymer. At the low shear rates encountered while it is being pumped down the drill pipe, the fluid is a low-viscosity, pumpable liquid. Yet as it passes through the drill-bit nozzles, the resulting high shear rates cause the fluid to thicken irreversibly into a high strength viscous paste.


Not What You Are Looking For?

For QUICK Help Call Us Now!

+234 813 292 6373

Here's what our amazing customers are saying

Ajayi Crowther University, Oyo
I was scared at first when I saw your website but I decided to risk my last 3k and surprisingly I got my complete project in my email box instantly. This is so nice!!!
Ahmadu Bello University
I wish I knew you guys when I wrote my first degree project, it took so much time and effort then. Now, with just a click of a button, I got my complete project in less than 15 minutes. You guys are too amazing!
Temitayo Ayodele
Obafemi Awolowo University
My friend told me about iprojectmaster website, I doubted her until I saw her download her full project instantly, I tried mine too and got it instantly, right now, am telling everyone in my school about, no one has to suffer any more writing their project. Thank you for making life easy for me and my fellow students... Keep up the good work
Very Good
Stancy M
Abia State University, Uturu
I did not see my project topic on your website so I decided to call your customer care number, the attention I got was epic! I got help from the beginning to the end of my project in just 3 days, they even taught me how to defend my project and I got a 'B' at the end. Thank you so much iprojectmaster, infact, I owe my graduating well today to you guys...
Ibrahim Muhammad Muhammad
Usmanu danfodiyo university, sokoto
It's a site that give researcher student's to gain access work,easier,affordable and understandable. I appreciate the iproject master teams for making my project work fast and available .I will surely,recommend this site to my friends.thanks a lot..!
Dau Mohammed Kabiru
Kaduna State College of Education Gidan Waya
This is my first time..Your service is superb. But because I was pressed for time, I became jittery when I did not receive feedbackd. I will do more business with you and I will recommend you to my friends. Thank you.
Very Good
Joseph M. Yohanna
Thanks a lot, am really grateful and will surely tell my friends about your website.
Merry From BSU
I am now a graduate because of, God Bless you guys for me.
Samuel From Ajayi Crowther University
You guys just made life easier for students. Thanks alot
Musa From Ahmadu Bello University
Thank you iprojectmaster for saving my life, please keep it up and may God continue to bless you people.