Review of casing while drilling technology

Abstract

Conventional drilling methods have been plagued with huge operational and financial challenges, such as cost of purchasing, inspecting, handling, transporting the drill equipment and most importantly, tripping in-and-out of the drill string whenever the Bottom Hole Assembly (BHA) needs a replacement, needs of wiper trip or when total depth is reached. The tripping in-and-out of the drill string not only contributes to Non Productive Time (NPT) but also leads to well control difficulties including wellbore instability and lost circulation. All this has led Oil and Gas industry, as well as any other engineering industry, to seek for new ways and methods in order to reduce these problems. Thanks to the advances in technical solutions and constant improvements of conventional drilling methods, a new drilling method -casing while drilling has been developed. Casing Drilling encompasses the process of simultaneously drilling and casing a well, using the active casing and thus optimizes the production. This paper presents a review of casing while drilling method (CwD) and its practical usage in drilling wells. The comparison of conventional drilling method and casing while drilling is also presented. The CwD method achieves significantly better results than conventional drilling method. Keywords: casing, drilling, CwD, application Apstrakt: Konvencionalne metode bušenja se suočavaju sa raznim operativnim i finansijskim izazovima poput troškova nabavke, inspekcije, održavanja i transporta opreme za bušenje, a najviše sa konstantnim manevrom bušaćeg alata bilo da je potrebno da se proradi izbušeni interval, da se zameni kompozicija teškog alata ili po dostizanju konačne dubine bušotine. Konstantan manevar bušaćeg alata doprinosi ne samo povećanju neproduktivnog vremena već i poteškoćama prilikom bušenja, ukljućujući i nestabilnost kanala bušotine kao i gubitak cirkulacije. Svi navedeni problemi doveli su do razvoja novih rešenja i metoda među kojima se posebno istakla nova metoda bušenja -metoda bušenja kolonom zaštitnih cevi (casing while drilling). Casing while drilling metoda objedinjuje proces bušenja i cementacije bušotina i na taj način rešava probleme konvencionalnog bušenja. Ovaj rad opisuje novu metodu bušenja pomoću kolone zaštitnih cevi -casing while drilling (CwD) kao i njenu praktičnu primenu u procesu bušenja. Izvršeno je poređenje konvencionalne metode bušenja i CwD metode i iz svih opisanih studija slučaja ustanovljeno je da CwD metoda pruža bolje performanse od konvencionalnog bušenja.

Field Testing of a Novel Drilling Technique to Expand Well Diameters at Depth in Unconsolidated Formations

“…Limitations are due to risks of mechanical failure inhibiting retraction of the blades and causing downhole loss of the drilling assemblies (Bruce 2012;Kamp 2018). Therefore, for consolidated formations, the maximum reported expansion ratio (1.3) (e.g., Brown and Gledhill 2003;Kerunwa and Anyadiegwu 2015;Schlumberger 2020) and diameter (406 mm) (Pavković et al 2016) are lower. "Scrape drilling" is an underreaming technique with small expansion ratios (factor 1.05) intended to prevent initial clogging by scraping the filter cake of the borehole wall before backfilling (Olsthoorn and Harlingen 1994;Kortleve 1998;Segalen et al 2005).…”

Comprehensive Review on Exploration and Drilling Techniques for Natural Gas Hydrate Reservoirs

“…The variants of CWD include the following: (a) Nonretrievable BHA: The non-retrievable system is the simplest and most commonly used where rotation of the string is required but does not pose directional trajectory change capability. 154 (b) Retrievable BHA: The retrievable system can be steered and used with both conventional measurement while drilling (MWD) and logging while drilling (LWD) tools. It can also drill both straight and directional holes effectively.…”

“…153 (c) Retrievable liner BHA: The retrievable liner system does not involve the use of a casing drive system and is capable for all deepwater applications. 153 Advantages of CWD include the following: 154,155 (a) reduces well instability and hole problems (lost circulation, differential stuck up, and wellbore collapse) as a result of the "plastering effect", (b) reduces associated non-productive time (NPT) and enhances safety, (c) skin damage becomes significantly reduced, (d) reduces cementing cost as a result of a more perfect gauged hole, (e) cuttings reach the surface more quickly as a result of the increased annular velocity, (f) reduces manpower requirement, and (g) avoids the need of extra casing strings.…”

Perspectives for development of ice drilling technology: continuation of the discussion

“…However, modification of the tools and materials for deep drilling represents a fairly new approach. In the late 1990s, the idea of CWD was finally accepted in the oil and gas industry (Bojan and others, 2016). A nonretrievable CWD system comprises a drillable bit or drill shoe, a casing string and a casing drive system to rotate the casing (Fig.…”