1.1 IntroductionThe most widely procedure that were conductedin extracting the hydrocarbon is by applying rotation method which require aweight over drillstring. This method will affect the original geologicalformation until the reservoir is reached.
However, in certain cases, the mostprevalent problem that occurs in drilling operation is lost circulation. As far as this proposalhas been discussed, lost circulation is crucial drilling problems especiallywhen in highly fractured formation, cavernous formation and not to mention,highly permeable depleted reservoirs also tend to have high possibilities inlost circulation during drilling. Infact, during cementing operation, lost circulation could also happen in cementslurries which fractures in the wellbore are widened by drilling fluidpressure. The complications thatoccurred during the drilling operation can be very costly. Even with the bestdrilling practices, lost circulation still able to occur.
Lost circulation notonly change the permeability and wettability of rocks but also affectmanagement and production time including cost. The oil and gas industry reflectand serves an extraordinary revolution in both materials science and inengineering practices.Well, to put it in anutshell, the main point will be discussing in this chapter specifically owingto the study of Citrus Sinensis as lost circulation material in synthetic basedmud. 1.2 DrillingFluids1.2.
1 Function of Drilling FluidsExploration of oil and gas field might tobe difficult to achieved without the drilling fluids. Table 1 summarized the basicfunction of drilling fluid in oil and gas industry. Drilling fluid is keyperformance drilling operation where without proper planning, catastrophicevent might have occurred. In fact, thesuccessful completion of a petroleum exploration and development phase aredepending on the properties of drilling fluid (Williamson, D. et al.
, 2013). Table 2.1Basic Function of Drilling fluids Function Descriptions Controlling formation pressure The specialized formulated drilling fluid that pumped into the wellbore will help to control the formation pressure by using specific additives Removing cutting from borehole The drilling fluid the circulates will brings up the cutting while promoting good hole cleaning. Sayindla S. et al (2017) studies that insufficient hole cleaning may can cause in reducing rate of penetration (ROP) formation fracturing and stuck pipe.
Cooling and lubricating the bit The drilling fluid will help to cool down the drilling bit. This is due to the excessive friction force applied on the drilling bit will tend to further wear the bit. Source:Williamson, D. (2013).
Drilling Fluid Basics. Oilfield Review Spring, 25(1).Retrieved on October 20, 2017 from www.slb.com/resources/oilfield_review/~/media/Files/…
/defining_fluids.ashx 1.2.2 Types of Drilling FluidThere are two different system in drillingfluid, which are continuous phase (consist of liquid) and discontinuous phase(consist of solids). The continuous phase can be further divided into twodifferent categories; aqueous and non-aqueous drilling fluids.
Figure 2.1 showsthe types of drilling fluid that have been used recently in the industry. Drilling fluids arecommonly used in transporting the cuttings to the surface and it is crucial forthe drilling operator to be able to decide an appropriate fluid for eachdrilling condition, including the decision of using a specific types ofdrilling fluids.
Each of these types have its own advantages and disadvantages,as being studied by Apaleke et al. (2012). Currently, the drilling fluids havebecome more complex in term of formulation and expensive due to the diverserequirement that need to be fulfil so that the drilling fluid may cater all itsbasic functions (Sayindla, S. et al., 2017). Many researches have beenworking with these types of drilling fluids; water-based mud, oil-based mud andsynthetic-based mud, but conclusions differ.
Table 2.2 lists the previousstudies that have been conducted in determine the behavior of drilling fluid.There are no standard requirements available which recommend the types ofdrilling fluid to be used for a particular drilling condition or a particularwell. Figure2.1 Types of Drilling FluidSource:Jack (2015).
Types of Drilling Fluid. Retrieved on October 11th,2017 from http://www.oilngasdrilling.
com/wp-content/uploads/2015/04/types-of-drilling-fluids.jpg Table 2.2Previous studies of drillingfluids Types of Drilling Fluid Authors Conclusions Oil-Based Mud (OBM) Sayindla, S. et al.
(2017) This paper also states that the same rheological properties OBM to WBM is much better that WBM when it comes to its basic function of hole cleaning. Field studies demonstrates that by using OBM might improving the rate of penetration (ROP), however, laboratory studies indicate that it is not obvious that ROP improves with OBM. Oil-Based Mud (OBM) Sasen and Loklingholm (2002) In his study, it is found that the OBM have better efficiency as compared to water-based drilling fluid when they evaluating field data. Sorgard et al (2001) However, despite its superior hole cleaning, OBM become less favorable types of drilling fluid under extremely cold-water conditions. This due to the OBM become sluggish and increase in viscosity with results in increased of equivalent circulating density (ECD) which can cause fracture of formation. Ning et al. (2013) In hydrate formation condition, OBM is more favourable due to lover induction time for hydrate formation as compared to water-based mud.
This investigation has been conducted by Srungavarapu, M. et al. (2017) in his studies. It states gas is readily dissolvable in oil than water cause the induction time of hydrate formation in OBM is low. Werner, B. et al.
(2017) These researches have compared the performance between OBM and WBM and it is completely proved by laboratory results that OBM has shows a magnificent cuttings-transport ability to the WBM. Oil-Based Mud (OBM) Abduo, M. I. et al. (2015) Differ from the Sorgard’s research, Abduo demonstrates in his studies that OBM have numerous advantages; for instances OBM has faster penetration rates, shale stability and providing better gauge hole. Moreover, an excellent drilling fluid is the one that can drill under excessively high temperature and high pressure. In his case, OBM able to withstand high temperature over a long period of time. Table 2.
2(Continued) Water-Based Mud (WBM) Abdua M. I. et al. (2015) The high level of toxicity of OBM gave urgency to the environmental issues.
Not only, OBM can be harmful to environment, it also can be damaging the equipment especially the rubber type of equipment. Due to these concerns, the study of WBM in high-temperature and high-pressure have been favorably preferred than OBM. From the results of this paper, it can be observed that OBM is the most appropriate drilling fluid in dealing with such conditions if not violating the environment regulations.
In fact, it is crucial to design an eco-friendly WBM for HPHT drilling. Patel, A. et al. (2009) and Lal, M. (1999) Even though WBM is less toxicity as compared to OBM and SBM, there are numerous typical issues encountered with WBM, for instances, swelling of shale formation which consequently led to lost circulation and hole collapse. Synthetic Based Mud (SBM) Stout, S.
A. et al. (2017), Neff et al.
(2000), American Chemistry Council (2006) These papers have proven that synthetic-based mud provide spectacular advantages than OBM in terms of environmental concerns. This is due to the fact that SBM are designed to be low in toxicity level and rapid degradation process in marine sediments. Subhash, N. et al (2010) The difference between OBM and SBM is the type of base fluid used, for instances, SBM used synthetic material instead of oil.
This paper also demonstrates that the toxicity level of SBM is low because the aromatic content in SBM is low. Besides, in this study, SBM base fluids and degradation products also exhibit low in toxicity level which passes local acceptance criteria in Europe. Hence, SBM is proven to be environmentally friendly. Akbar A. et al.
(2016), Samira, B. H. et al. (2009), Environmental Protection Agency Part III (1999) In oil well drilling operations, these paper approaches ester-based drilling fluids which it had been recognized for magnificent performance of any synthetic-based mud. Besides, they are full bio-degradable drilling fluids, in other words, they able to improve drilling performance efficiency without polluting the environment.
Based from the Table 2.2, it shows thateach system of drilling fluid has their advantages and disadvantages related toenvironmental impact, cost and reliability in extreme conditions. Drillingoperator must have decided the best in order to minimize the drilling problemlater on.
Besides, the main point of select drilling fluid is fluid that haveimpressive rheological properties and should be allow to drill at controlledpenetration rate along with low filtration loss as being suggested bySrungavarapu M. et al. (2017). The typical characterization of synthetic-basedmud has been tabulated in the Table 2.3 and Table 2.
4 which were provided byBaroid and Baker Hughes (Ali, A. D. et al., 2016). These mud propertyspecifications is the one of the SBM system that currently being utilized inGulf of Mexico deep-water drilling operations.
Table 2.3Synthetic-Based Drilling FluidSpecifications Recommended by Baker Hughes Mud Weight, lb/gal Plastic Viscosity, cp Yield Point, lb/100ft2 Emulsion Stability, Volts 10.5 – 10.9 35 – 45 15 – 20 >400 10.9 – 14.1 45 – 55 12 – 18 >400 14.1 – 15.
1 50 – 60 10 – 15 >500 15.1 – 15.2 50 – 60 10 – 15 >500 15.2 – 15.5 50 – 60 10 – 15 >500 Source:Ali, A.
D. et al. (2016). Experimental investigation of new additive tooptimize the properties of synthetic-based drilling fluid. Journal of Mining and Metallurgy, 52A (1), 37-43. Table 2.
4Synthetic-Based Drilling FluidSpecifications Recommended by Baroid Mud Weight, lb/gal Plastic Viscosity, cp Yield Point, lb/100ft2 Gel Strength, lb/100ft2 HPHT Fluid Loss 10.5 – 10.9 35 – 45 15 – 20 8, 15, 18 <4 cc/30 min 10.
9 – 14.1 45 – 50 12 – 18 12, 18, 20 <4 cc/30 min 14.1 – 15.1 50 – 60 10 – 15 15, 22, 25 <3 cc/30 min 15.
1 – 15.2 50 – 60 10 – 15 18, 25, 28 <3 cc/30 min 15.2 – 15.5 50 - 60 10 - 15 20, 28, 31 <3 cc/30 min Source:Ali, A.
D. et al. (2016). Experimental investigation of new additive tooptimize the properties of synthetic-based drilling fluid.
Journal of Mining and Metallurgy, 52A (1), 37-43.