Drilling Fluid

The increase of the demand of oil and also the price causes research in inventing new technology such as non-damaging lost circulation pills (LCP) to produce more oil with less cost. Optimizing the LCP compositions to stop the lost circulation effectively and also protect the production zone from liquid and solids invasion significantly. Key parameters include of Shape, particle size distribution and concentration of the lost circulation materials (LCM) are necessary to determine the effectiveness of LCP.In this study, the Permeability Plugging Apparatus (PPA) is used to evaluate effectiveness of sized calcium carbonates in different concentrations to cure the lost circulation. Ceramic disks with nominal pore sizes 20, 35, 60 microns, are used to simulate lost circulation zones. Spurt loss and filtrate volume are primary parameters to be evaluated in this research.

Selected local cassava (Manihot esculenta Crantz) starches were investigated as additives for water-based drilling mud. Cassava cultivars, TMS 30572, TMS 98/0505, TMS 98/0581, M98/0068, TMS 92/0057, TMS 96/1632, NR8082, TME 419, TMS 97/4779 and TMS 01/1412 were processed to starches and used for drilling mud treatment at 0.5, 1.0 and 2.0 percent. Polyanionic cellulose (PAC), xanthan gum (XG) and industrial starch-modified drilling muds served as controls. Physicochemical analysis of the starches showed significant differences in their properties. Viscosity and fluid loss profiles revealed that some of the local cassava starches had comparable performance with the commercial polymers. The optimal concentration of the industrial starch in the mud system was 0.5 percent, while that of the local starches were between 0.5 and 1.0 percent. PAC and XG performed best at 1.0 and 2.0 percent respectively. The highest viscosities were shown by muds treated with TMS 98/0581, XG, TMS 96/1632, M98/0068, TMS 92/0057 and PAC, arranged in decreasing order. And the lowest fluid losses were exhibited by muds with PAC, industrial starch, XG, TMS 98/0581 and M98/0068 in increasing order. Viscosity and fluid loss models as functions of cassava starch physicochemical properties were developed. Increase in starch content, amylose content, solubility index would readily increase viscosity, while high starch content, amylopectin content, solubility index and pH would reduce the fluid loss. Local starches from TMS 98/0581, TMS 96/1632 and M98/0068 and TMS 92/0057 could be used as a substitute in drilling mud as viscosity enhancers and fluid loss control agents in Nigeria.

During the drilling process, we need to look at several aspects that need to be considered, including the drilling mud aspect which is one of the important aspects in a safe and efficient drilling process.The success of a drilling process through various rock layers is very dependent on the design of the drilling mud formulation. All of that can be influenced by the nature and physics of the drilling mud which needs to be adjusted to the formation conditions, formation pressure, rock type and fluid content contained in the formation. In designing the mud formulation that will be used, it can be done by using the mud system correlation method or by analyzing the pressure wells that become offset wells or key wells which are analyzed to determine the properties of the mud to be used. Well GG – 01 is an exploration well so it does not have an offset well. The drilling that will be penetrated is as many as 4 routes which in the first route the hole is made using a mash system so that it...

Salt formations are encountered in many oil-producing regions of the world. These salt zones can be in a variety of forms; salt domes, massive beds and sheets or lenses. The chemistry of salts can very significantly even in a single bed, from pure sodium chloride to very complex blends of mixed chloride

laboratory from scratch in 2009 and filed in excess of 200 patents, more than 100 already granted. Published more than 120 conference and journal papers and received several national, regional and international awards. Two of my patents were highlighted in scholarly editions of two books on "Advances in Research and Applications" that have been published in USA. Another two patents on Environment Friendly Base Fluid and Low Viscosity Dielectric Fluid (US patent 8563482 and US Patent 8440116) were included in 2014 patent list for AOCS Annual Meeting, USA. Some of my research activities were highlighted in national and international journals and magazines. Some papers were highlighted in the Journal of Petroleum Technology and some were published as the lead articles due to their technical significance. As per Google Scholar and Scopus reports-my h-index is 24 and 16 respectively and Google Scholar i10-index is 61, reported in October 2021.

Lost circulation of drilling fluid results in higher operational expenses which makes it imperative to design the fluid, such that minimal invasion of the fluid occurs in the formation. To achieve this, Lost Circulation Materials (LCM) are required which is expected to seal the fractures hence, the performance of Oyster Sea-shells (Crassostrea Virginica) as a lost circulation material is being investigated knowing that it is rich in Calcium Carbonate.

The development of new technologies in the past 10 years, like the MWD systems for
real-time surveying, steerable systems for an effective control of trajectory, PDC bits for
efficient drilling of long sections, mud and hydraulic systems for improved control of
hole cleaning and borehole stability, etc. have transformed directional drilling into a
common practice.
There are a few serious problems which may arise during the course of drilling a
directional well. The probability of certain drilling problems arising (e.g. differential
sticking) is increased by virtue of the well being deviated. The causes and implications of
differential sticking are discussed here, as well as solutions and possible preventive
measures. This is very relevant to the DD, particularly in areas which are prone to
differential sticking.
Dog legs and key seats are discussed here in detail. As mentioned elsewhere in this
manual, it is the DD’s responsibility to ascertain the client’s limit on dog leg severity at
the beginning of the project. The consequences of high dog leg severity at a shallow
depth often do not become apparent until much deeper in the well.
Problems caused by borehole instability due to poor hydraulics and mud conditioning are
outlined. Increases in Drag, particularly when drilling with a PDM, directly concern the
DD. In high-angle wells, it often becomes very difficult to "slide".

Salt formations are encountered in many oil-producing regions of the world. These salt zones can be in a variety of forms; salt domes, massive beds and sheets or lenses. The chemistry of salts can very significantly even in a single bed, from pure sodium chloride to very complex blends of mixed chloride

The production of drilling mud using pectin extracted from Citrus Sinensis peels was carried out. The extraction was carried out using water-hot acid technique which is a conventional method, and the extracted pectin was pre-gelatinized using calcium water. The pre-gelatinized pectin biopolymer was used to prepare drilling mud. Filter loss method was used to determine the filtration properties of the mud at 25°C and 200°C and 0.1g/mol concentration of pectin polymer was compared to the filtration behavior of hydroxyl propyl starch modified drilling mud. Our results showed that the pectin biopolymer mud (PPM) has better filtration control behavior than the hydroxyl propyl starch modified drilling mud (CMM). The study also showed that highest sorptivity value of 21.25 was obtained with PPM at 200°C, while the highest diffusivity value of 0.424 was obtained with CMM at 200°C.

This paper aims to review some of the widely used conventional and other contemporary Inflow & Productivity models that exist for Horizontal wells, and comment on their limitations by drawing on the experiences of other author's critiques on these IPR models.

Permeability impairment caused by drilling fluids and subsequent cleaning and permeability enhancement by backflow are investigated by means of experimental and simulation studies. Damage caused by two different drilling fluids is measured experimentally by core tests as a function of the filtration pressure and analyzed using a simulator describing the fines migration and retention in porous media. Simulations were run both with experimental and synthetic data in forward and backward directions along the core samples. Permeability was correlated with respect to drilling filtration pressure in terms of the deposited particle volume fraction. The clean-up time was determined after back-flush with fresh water and improvement was observed both in porosity and permeability. Simulation results accurately match the experimental data, indicating that this simulator can be used for the estimation of permeability reduction and the permeability and porosity variation along the core samples at various filtration pressures. It was also determined that a polymer-added drilling fluid characterized with 65% permeability damage ratio may be the optimum drilling fluid causing less formation damage than the water-based bentonite mud.

A review of the acute and chronic effects of produced formation water (PFW), drilling fluids (muds) including oil-based cutting muds, water-based cutting muds, ester-based cutting muds and chemical additives, and crude oils associated with offshore oil and gas production was undertaken in relation to both temperate and tropical marine ecological processes. The main environmental effects are summarized, often in tabular form. Generally, the temporal and spatial scales of these studies, along with the large levels of inherent variation in natural environments, have precluded our ability to predict the potential long-term environmental impacts of the offshore oil and gas production industry. A series of critical questions regarding the environmental effects of the offshore oil and gas production industry that still remain unanswered are provided for future consideration. Ó

One of the desired properties of a drilling mud is that it should minimize fluid loss from the wellbore into the surrounding permeable formation. It is preferable that the quantity of liquid lost to the surrounding formation and the thickness of the filter cake formed be held to a minimum. The fermentates employed for purposes of the invention are produced by the fermentation of carbohydrate solutions with bacteria of the genus Xanthomonas. Specific Xanthomonas organisms employed includes Xanthomonas begonia, Xanthomonas campestris, Xanthomonas hederae etc. Experimental work showed that fermentates produced by members of this genus have properties, which are used for purposes of this invention.

Many industrially important non-Newtonian fluids such as drilling fluids and cement slurries exhibit yield-pseudo-plastic behavior. The axial laminar flow of such fluids in concentric annuli has received very little attention to date. This problem was first studied by , who presented results obtained for the Herschel-Bulkley rheological model. recently showed that Hanks' numerical results are erroneous in several cases.

The drilling fluid contact with the productive zone of drilling wells, with horizontal or complex configurations, can reduce its productivity by fluid invasion in the borehole wall. Drilling fluids usually comprise natural polymers as starch and xanthan gum. These polymers are deposited as a filter cake on the wellbore wall. A common approach to remove this filter cake is the application of acids or strong oxidative solutions. However, these are non-specific species and a possible alternative lies in enzymatic preparations that are able to hydrolyze such polymers. The enzymes catalyze specific substrates, are environmentally friendly and the enzymatic degradation rate is slower than that achieved by the oxidative species, permitting to produce uniform degradation of the filter cake. Openhole operations require thermo and pressure stability of these enzymatic products. The results herein reported deals with the technical viability analysis of a commercial α-amylase as a new catalyst for filter cake removal. The effects of process parameters, like temperature (65, 80 and 95°C), enzyme concentration (1, 5.5 and 10% v/v), calcium concentration (5, 70 and 135 ppm), and pressure (100, 500, 100 and 6000 psi), on amylase stability under openhole operations were investigated. Temperature demonstrated to be the most important parameter for the enzyme stability. The enzyme thermostability behavior in high salt (NaCl) concentration (completion fluid) was not significantly different from the control solution in distillated water. The pressure effect on enzyme stability did not affect the enzyme stability as temperature. Hydrostatic pressure (6000 psi) did not impact the amylolytic activity in brine solution. Combined pressure-temperature assays showed that temperature is the key factor in enzyme stability for application in polymeric filter cake removal in petroleum wells. Queiroz Neto), [email protected] (M.A.P. Langone), [email protected] (M.A.Z. Coelho). 0920-4105/$ -see front matter

In this paper, a comprehensive review of experimental, numerical and artificial intelligence studies on the subject of cuttings settling velocity in drilling muds made by researchers over the last seven decades is brought to the fore. In this respect, 91 experimental, 13 numerical simulations and 7 artificial intelligence researches were isolated, reviewed, tabulated and discussed. A comparison of the three methods and the challenges facing each of these methods were also reviewed. The major outcomes of this review include: (1) the unanimity among experimental researchers that mud rheology, particle size and shape and wall effect are major parameters affecting the settling velocity of cuttings in wellbores; (2) the prevalence of cuttings settling velocity experiments done with the mud in static conditions and the wellbore in the vertical configuration; (3) the extensive use of rigid particles of spherical shape to represent drill cuttings due to their usefulness in experimental visualization, particle tracking, and numerical implementation; (4) the existence of an artificial intelligence technique-multi-gene genetic programming (MGGP) which can provide an explicit equation that can help in predicting settling velocity; (5) the limited number of experimental studies factoring in the effect of pipe rotation and well inclination effects on the settling velocity of cuttings and (6) the most applied numerical method for determining settling velocity is the finite element method. Despite these facts, there is need to perform more experiments with real drill cuttings and factor in the effects of conditions such as drillstring rotation and well inclination and use data emanating therefrom to develop

Experiments were conducted to evaluate the membrane character of native shale samples by measuring the electrochemical potential across the shale membrane. Results suggest that the composition of the interstitial pore fluid in the shale plays a determining role on the establishment of the electrochemical potential and that, in some cases, the behavior of the shales is close to the expected behavior of a perfect cation-selective membrane. Shales with intermediate electrochemical potentials Ž appear to be more sensitive to water-based fluids than shales that are closer to perfect membranes high electrochemical. potential. A model to simulate the transport of water and ions through shales was developed. Hydraulic pressure, concentration, and electric potential gradients are the driving forces for the flow of water and solute between two solutions separated by the shale. The reflection coefficient and the modified diffusion potential are calculated from the model and are used to characterize the membrane behavior of shales. A sensitivity study on the various model parameters was conducted. Results show that the membrane efficiency of the shale is strongly affected by the concentration of the interstitial fluid, the separation distance between the platelets and the type of ions in the membrane. The higher the ion concentration and the interplatelet spacing, the lower the efficiency. Results obtained using the model produce reflection coefficients that are consistent with experimental data. The model provides excellent insight into the physical mechanisms responsible for the membrane behavior of shales and a way to conduct sensitivity studies on the important model parameters. The membrane efficiencies obtained from the model may be used in wellbore stability simulators to account for chemical interactions between shales and water-based drilling fluids.

Drilling for water, oil, or even gas using water-based drilling fluids faces major challenges. These are mainly related to drilling fluid leakage into the surrounding formation, water loss into fractures, and the reduction of fluid density or/and viscosity through the drilling circulation process. Nanoadditives with high surface to volume ratio of carbon nanoparticles (CNP), ~50nm, and ZnO nanowires provide significant control of drilling fluid rheological properties. CNP additives were found to maintain the homogeneity of the drilling fluid components for a longer time and delay fluid sagging effect. Drilling fluid densities were enhanced by a factor of 4-10% after addition of CNP or ZnO nanowires to the untreated drilling fluid by 1-3 wt. %. Progressively, when 1, 2 and 3g of CNP was added to the drilling fluid, the resultant filtrate water volume was reduced by 7, 4.8 and 4mL respectively. The maximum water loss reduction measured was about 50% of the total fluid loss. Additional...

water-based drilling fluids waxy hull-less barley β-glucan viscosity tests Xanthan gum carboxymethylcellulose This paper offers a comprehensive, comparative study of rheological properties of aqueous solutions of waxy hull-less barley (WHB). Rheological properties of aqueous WHB solutions were compared to hydrocolloid systems prepared by using sodium bentonite, Xanthan Gum, and cellulosic biopolymer (CMC), which are some of the most common additives used for formulating drilling fluids in the oil and gas industry. Samples were prepared at various concentrations in freshwater and saline solutions, and tested for temperature aging at 90°C. Viscosity measurements at various shear rates were performed on each sample. WHB performed reasonably well as a viscosifying agent, especially in saline, high temperature environments.

Fluid loss control is generally achieved by increasing the shear viscosity of the fluid and developing an internal/external filter cake using fluid loss control additives. If the viscosifiers and fluid loss control additives are not selected properly, both mechanisms may lead to a significant reduction of permeability. Moreover, increasing the fluid shear viscosity may not be desirable all the time due to the high annular pressure losses (i.e., the ECD limit), in particular, when drilling long horizontal and extended reach wells. In this paper, a new methodology is presented to formulate an "ideal well fluid", which effectively reduces the fluid loss into the formation without causing additional frictional pressure losses in the well. Blends of a water-soluble Polyethylene Oxide (PEO) with different molecular weight distributions and similar average molecular weights (Mw) were prepared. The PEO blends were then used to prepare aqueous polymer solutions, which had similar shear viscosities but significantly different elastic characteristics (i.e., normal stress and relaxation time). Core flow experiments were conducted to investigate the effects of viscoelastic fluid rheology on the formation of "internal cake" (i.e., frictional pressure drop). It was possible to see the effect of fluid elasticity on the frictional pressure losses alone because both fluids had the same shear viscosity but different elastic properties. The resistance of the fluid with higher elasticity to flow through a porous medium was significantly higher than that of the fluid with lower elasticity. The experimental results indicated that the filtration of a polymer-based fluid into a porous medium could be considerably reduced by increasing the elastic properties of the solution through controlling the molecular weight distribution of the polymer, while keeping the shear viscosity and concentration of the polymer constant. Specifically, the formation damage risk of polymer-based drilling fluids could be minimized without inducing additional pressure drop due to fluid flow inside the well.

An organosilicon quadripolymer of acrylamide (AM), 2-acrylamido-2-methyl-1-propane sulfonic acid (AMPS), N-vinylpyrrolidone (NVP) and a kind of organosilicon monomer was synthesized by solution free radical polymerization. The chemical structure of organosilicon quadripolymer was characterized by Fourier transform infrared (FTIR) spectroscopy, and molecular weight distribution was determinate by gel permeation chromatography (GPC) under the best optimum synthesis conditions, which were identified by orthogonal test according to filtrate volume of fresh water-based drilling fluid. The colloidal properties of the organosilicon quadripolymer drilling fluid were investigated in various media such as fresh-water, 4.0% salt-water, and saturated brine based fluid. The results showed that the filtrate volume decreased with the increase of the organosilicon quadripolymer concentration before and after the thermal aging test at 180 C for 16 h, and the filtrate volume after the thermal aging test was larger than that before the thermal aging test, but was smaller than the base fluid. The colloidal properties and the filtrate volume could be controlled effectively at aging temperatures not exceeding 200 C. The organosilicon quadripolymer drilling fluid performance was better than corresponding terpolymer without organosilicon group and shows favorable inhibitive property and was an excellent fluid loss additive for drilling fluid resisting high temperature in deep wells. A possible mechanism is proposed to explain the improvement according to the comparative adsorption experiment.

. Characterization of drilling mud fluid invasion. J. Pet. Sci. Eng., 1: 3-13. A method for the characterization of drilling mud fluid invasion of porous formations was developed. The oil saturation and resistivity profiles are determined as a function of radial distance from the well and time using a finite difference solution of the radial form of the diffusivity equation. The coefficient of dispersion and its variation with respect to time was determined for five sandstones using long cores. The effluent profile of a step increase of injected sodium chloride concentration is analyzed to determine the value of the coefficient. Values reported in the literature for the dependence of the mud filtration rate on time of filtration were used. The method gives a complete analysis of mud filtrate invasion and can be used for improvement of resistivity well log interpretation.

A number of rheological models are examined to establish how well they can characterise a data set of different, pseudoplastic, non-Newtonian fluids used in North Sea operations when their parameters are evaluated using the 'direct' parameter calculation procedure. The study considers how modelling accuracy is affected by the choice of rotational viscometer readings used to calculate these parameters and provides the necessary expressions for direct parameter solution. Conventional measurement combinations of rotational viscometer readings fail to deliver the accuracy provided when non-conventional reading combinations are employed. As such, recommendations for suitable 'default' rotational viscometer measurement combinations are given for each rheological model. It is also concluded that the three-parameter model of w Ž .

A number of rheological models are examined to establish how well they can characterise a data set of different, pseudoplastic, non-Newtonian fluids used in North Sea operations when their parameters are evaluated using the 'direct' parameter calculation procedure. The study considers how modelling accuracy is affected by the choice of rotational viscometer readings used to calculate these parameters and provides the necessary expressions for direct parameter solution. Conventional measurement combinations of rotational viscometer readings fail to deliver the accuracy provided when non-conventional reading combinations are employed. As such, recommendations for suitable 'default' rotational viscometer measurement combinations are given for each rheological model. It is also concluded that the three-parameter model of w Ž .

One of the desired properties of a drilling mud is that it should minimize fluid loss from the wellbore into the surrounding permeable formation. It is preferable that the quantity of liquid lost to the surrounding formation and the thickness of the filter cake formed be held to a minimum. The fermentates employed for purposes of the invention are produced by the fermentation of carbohydrate solutions with bacteria of the genus Xanthomonas. Specific Xanthomonas organisms employed includes Xanthomonas begonia, Xanthomonas campestris, Xanthomonas hederae etc. Experimental work showed that fermentates produced by members of this genus have properties, which are used for purposes of this invention.

In this work, a drilling fluid recipe has been developed by using nanoparticles, to increase the efficiency of drilling operations for maximum accessibility to new & matured oil reserves and suited to various drilling conditions. The solution to severe drilling problems like pipe sticking, lost circulation, formation damage, erosion of borehole, thermal instability of drilling fluids and insufficient gel properties of the drilling fluids, lies in controlling and optimizing the rheology of the drilling fluid. The inefficiency of the drilling fluid in performing certain functions is mainly due to a lack in a particular rheological property. The performance of the clay composites water-based bentonite drilling mud in terms of its rheological behavior in drilling systems was investigated at various pressures and temperatures. It was found that temperature had a detrimental effect on the rheological properties. The behavior was investigated using synthesized nano bentonite water based drilling fluid. The fluid retained all the desired rheological properties at elevated temperatures and pressures, thus enhanced the possibility of its application in deep wells, where elevated temperatures and pressures were quite common.

Experimental data is presented for the flow of bentonite-water dispersions, modeled as Herschel-Bulkley fluids, for the pressure loss at different flow rates covering laminar, transitional and turbulent flow regimes, while flowing in concentric and fully eccentric annuli. The concentric experimental data has been compared with predictions from a recently-introduced model which covers the full flow regimes for concentric annulus, while corrections for eccentricity, previously suggested for non-Newtonian fluids, have also been used to compare with eccentric data. Laminar flow data not only from this work but also from work from the literature is very well predicted while transitional and turbulent flow data are predicted with less accuracy, requiring improvements on predicting transition points. The corrections for eccentricity work well and can be used to accurately correct concentric annulus data. Turbulent non-Newtonian flow data exhibit a power law exponent relationship between flow rate and pressure loss smaller than the Newtonian case pointing out directions for future research.

The authors carried out the study to prepare chitosan Nisopropylacrylamide hydrogel via heating and radiation processes. Properties investigation of prepared samples revealed that radiation prepared samples show higher yield and swelling ratios in comparison with the heating prepared ones. Effects of hydrogel addition to drilling mud on its important rheological properties such as apparent viscosity, plastic viscosity, and stress-strain behavior are measured. The rheological properties of hydrogel were compared with cellulosemethylcarboxyl and resins that are widely used in drilling fluid. The results demonstrate that whereas linear polymer effects on mud properties are more significant in polymer low concentration, prepared crosslinked hydrogel effects are more significant at high concentrations.

This study investigates the growth of three life stages of T. guineensis exposed to different sublethal concentrations of Parateq for 12 weeks in a static renewal bioassay. Parateq a synthetic based Fluid (SBF) was added to water to obtain the following sublethal concentrations 0.32%, 0.63%, 1.25 % and 2.5% vol/vol. Fry (0.64cm -0.65cm/0.52g -0.55g) fingerlings (5.51cm-5.57cm/5.52g -5.56g) and Post fingerlings (7.21 -7.25cm / >10.5g) of T. guineensis were fed with NIOMR Feed. Proximate compositions of the feeds used were evaluated while the carcass composition of the fish was analyzed at the end of the experiment. Growth rates during the 12 weeks period were modest with fish in 2.5% of Parateq gaining the least weight. The highest percent growth rates were obtained from fish in control. The overall growth was significantly different between treatments and control. This study revealed that sublethal concentrations of toxicants will not only cause outright mortality but have significant effects which could lead to physiological dysfunctions in organisms that abound in the Niger Delta.

In this work, a drilling fluid recipe has been developed by using nanoparticles, to increase the efficiency of drilling operations for maximum accessibility to new & matured oil reserves and suited to various drilling conditions. The solution to severe drilling problems like pipe sticking, lost circulation, formation damage, erosion of borehole, thermal instability of drilling fluids and insufficient gel properties of the drilling fluids, lies in controlling and optimizing the rheology of the drilling fluid. The inefficiency of the drilling fluid in performing certain functions is mainly due to a lack in a particular rheological property. The performance of the clay composites water-based bentonite drilling mud in terms of its rheological behavior in drilling systems was investigated at various pressures and temperatures. It was found that temperature had a detrimental effect on the rheological properties. The behavior was investigated using synthesized nano bentonite water based dr...

Allium test has already been used to determine cytotoxicity of waste drilling fluids. In the present work the cytotoxicity of four pure chemicals (Defoamex, Idthin 400, Magco Thin and Slick Pipe) was investigated. Those chemicals are components of drilling fluids, therefore, they are usually constituents of oil and gas industry waste waters. The tested chemicals were prepared in 1:9 dilution

The effect of pipe eccentricity on the flow of well bore fluids in annuli is investigated both analytically and experimentally. The expression for azimuthal velocity as a function of the eccentricity ratio and rheological parameters of the fluid was obtained analytically using a linear fluidity model. Velocity profiles were measured for a Newtonian glycerol/water mixture and a non-Newtonian oil field spacer fluid in eccentric annuli using the stroboscopic flow visualization method. Measured velocity profiles in the eccentric annulus compare well to analytical predictions.

... Fluids with flat, low rheological values over extremes of temperature and pres-By Doug Oakley, Daryl Cullum, MI SWACO ... With the shallow and vertical wells being drilled at the time, drilling fluids com-prised no more than simple mixtures of water and clay. ...

Effective hole-cleaning is vital for a successful drilling operation and has significant effect on optimizing factors such as penetration rate, bit optimization and well stability. Efficient transportation of drilling cuttings are dependent on factors such as fluid properties and rheology, cuttings size and shape, fluid velocity, cuttings concentration, cuttings transport velocity and rate of penetration. This experimental work examined the effects of cutting sizes on drilling fluid rheology. To achieve this, two fresh samples of mud were prepared and the rheological properties were analyzed at different temperature ranges representing the operating conditions of most Niger Delta wells. A mesh analysis was carried on dried fresh drill cuttings from the Anieze North Field and dried cuttings taken from the laboratory and two samples were selected at ASTM#40 and #18. 10 % of these cuttings' samples were added to each mud sample and the rheological properties were measured at similar temperature ranges as the original mud samples. The results gotten shows that at the various temperature ranges, mud contamination with smaller drill cuttings size (ASTM #40=400um) showed a better performance than the larger particles. The mud rheological properties (viscosity, yield point, YP, plastic viscosity, PV and density) measured at different temperatures showed a remarkable non-linear behavior as shown in the results.

In this work, we report the preparation of a novel partially aminated and inexpensive water-soluble acrylic acid grafted activated carbon represented as C-g-AA-NH 2 for efficient inhibition of shale hydration. The as-prepared C-AA-NH 2 was subjected to Fourier transform infrared spectroscopy (FTIR), Nuclear magnetic resonance (NMR), and thermal gravimetric analysis (TGA). This was followed by an evaluation of the capability of the material to inhibit shale through various tests including anti-swelling, shale recovery, and immersion tests. Our results indicated that 2% of C-g-AA-NH 2 drastically reduced water invasion into shale by combining plugging property of the core-centered carbon nanoparticles with the inhibition ability of the partially aminated acrylic acid component by adsorption on the clay surface through hydrogen bonding. In this manner, the plugging of the pore throat of the interlayer spacing of the shale formation could easily be achieved. This approach could significantly control fluid loss, reduce permeability and filtrate volume of drilling mud by forming a thin film on the formation surface due to the nano-nature of the carbon component of the polymer.

The Niger Delta region of Nigeria is characterized with several drilling operations in the quest for hydrocarcons. Drilling fluids namely ClearBore, Bentonite and HydroPac were examined using Silicon fluid as standard Newtonian fluid. They are complex non-Newtonian fluid and key components of drilling mud. For each test fluid studied, there were five (5) replicates at varying concentrations and experimental results analyzed using the Power Law model. The main reason is to investigate the effects of varying fluid concentrations on the thermodynamic energy of the system. Empirical results showed that ClearBore, Bentonite and HydroPac are non-Newtonian fluids, although certain thixoropic properties were observed for ClearBore and Bentonite. Energy lost on experimental trials were observed to be reduced due to increment in the toque speed of the Rheometer. This has both cost advantage and of considerable importance in reducing drilling waste generated during drilling operations and well completions. Drilling fluid wastes not managed and disposed properly, could cause serious environmental contamination of land, marine, surface water bodies and ground water aquifer since they contain heavy metals and varying concentrations of hydrocarbons. These heavy metals and hydrocarbons could inflict haematological, biochemical and histopathological maladies on resident biota owing to their toxicity, persistence and bioaccumulative properties.