In this study, using the results of performed shale formation Characterizatins and the history of DRILLING in Iranian oil fields, an environmentally friendly WATER BASED DRILLING FLUID is designed to replace the oil BASED DRILLING FLUIDs. This DRILLING FLUID has desirable properties in DRILLING WATER sensitive formations. New DRILLING FLUID additives including shale inhibitors, new polymers and sized solid particles have been used to prepare this new DRILLING FLUID. The most important properties of this new DRILLING FLUID are controlling the mud filtrate and pressure invasion to the formation, clay mineral alteration and activity reduction, improvement of the integrity of DRILLING cuttings, reduction in formation damage, stability at high temperatures, stability in acidity changes and the compatibility by DRILLING FLUIDs dilution during DRILLING operation. The lubricity and shale cuttings recovery of this new DRILLING FLUID are better than those of other similar WATER BASED DRILLING FLUIDs. Replacing this DRILLING FLUID by oil BASED DRILLING FLUIDs in DRILLING industry will be a great means to protect the environment and DRILLING personnel in addition to being economically advantageous.

The rheological regulation of the “three high” (high temperature, high density and high salinity) WATER-BASED DRILLING FLUID is a worldwide problem due to the combined influence of temperature, solid content and salinity. This paper investigates the factors and regulation methods about rheological property of “three high” WATER BASED DRILLING FLUID, and the effects of clay, salinity and weighting materials on the DRILLING FLUID rheology. The experimental results show that base mud compound bentonite with attapulgite had good salt resistance and temperature resistance. The clay content should be kept close to 2% in high density mud (ρ=2.0g/cm3), to control DRILLING FLUID rheology. The sequence of rheological parameters of the “three high” WATER-BASED DRILLING FLUID with same density was: manganese oxide> micronized barite> barite> ilmenite powder. When barite compounded with ilmenite powder or micronized barite in the ratio of 1:1 to weight DRILLING FLUID respectively, the rheology and filtration of the “three high” WATER-BASED DRILLING FLUID performed well. BASED on the optimization of a series of mud additives including FLUID loss additive, thinner, anti-collapse filtration reducing agent, lubricant with salt and calcium resistance, a formula of the “three high”WATER-BASED DRILLING FLUID system was prepared which had excellent rheology, filtration and sedimentation stability property with the density of 2.2g/cm3 (180℃). The expansion rate of the DRILLING FLUID was 1.84%, shale recovery rate was 85.73%, lubrication coefficient was 0.122, and resistanced to pollution of 1% CaCl2 and 10% poor clay. It also had excellent reservoir protection and plugging performance.

BASED DRILLING FLUID, rheology modifier and enhanced oil recovery. Moreover, structure and microstructure of these polymers are of important in above-mentioned applications. Acrylamide homopolymer and acrylamide/styrene copolymer were synthetized using micellar polymerization for application in the WATER-BASED DRILLING FLUID. FTIR, NMR and some theoretical calculations were used to characterize (micro)structure of the polymers. In addition, conversion was obtained using gravimetric method. Ubbelohde viscometer was used to evaluate viscosity-average molecular weight. Apparent viscosity was measured by Brookfield viscometer. Synthesized polymers were used in the WATER-BASED DRILLING FLUIDs with three different concentrations and rheological and FLUID loss properties were evaluated before and after hot rolling at 120 ° C for 16 h. Moreover, FTIR and NMR results showed successful synthesis of the homo-and copolymers with high conversions. Average hydrophobic styrene block length was calculated by theoretical method to be 3. Results showed that both conversion and molecular weight values were higher in the case of synthetized homopolymer. It was attributed to increase in the possibility of chain transfer to surfactant in the micellar copolymerization reactions. Results showed that despite higher molecular weight in the acrylamide homopolymer case, viscosities of the acrylamide/styrene copolymer aqueous solutions were better in similar concentrations. It was attributed to the hydrophobic association between styrene units. Finally, results showed that both homo-and copolymer caused an improvement in the rheology and FLUID loss properties of the WATER-BASED DRILLING FLUID. Although rheological properties were reduced after hot rolling or in the presence of salt in the DRILLING FLUIDs, DRILLING FLUIDs prepared with acrylamide/styrene copolymer showed more ability to preserve their rheological properties due to the formation of physical network resulting from the hydrophobic associations.

Starch reduces FLUID loss while enhancing viscosity in DRILLING FLUID formulation. Starch obtained from soursop (SS) was chemically modified by carboxymethylation methods (SC1 & SC2) and acetylation method (SA) and compared with cassava (CN). The physicochemical properties: swelling power, gelatinization temperature, thermal stability and particle size, rheological properties: yield point (YP), gel strength and plastic viscosity (PV) and also FLUID loss control of the starches were investigated to determine their performance as viscosity enhancer and FLUID loss control ability in DRILLING FLUID. The results obtained revealed that modified starches (SC1 and SC2) demonstrated better physicochemical properties than SA, SS and CN. Thus, showing that carboxymethylation improved the thermal stability and gelatinization temperature of the starches. The morphology result revealed that modification reduced the particle size of the starches thereby, increasing their surface area and reactivity. In addition, the native and modified soursop starches exhibited good rheological properties and FLUID loss control as required by API standards. However, modified starch, SC2 exhibited better rheological properties in PV, YP, gel strength and controlled filtration-loss than other starches SC1, SA as well as native soursop and cassava. The possession of these excellent properties places soursop and its modified starches (SCI and SC2) as potential replacement for cassava as additives in DRILLING FLUID formulation. This will help improve efficiency in DRILLING operations, and on the other hand help to reduce the negative impact on food security in Nigeria since soursop is mainly consumed as a dessert.

DRILLING FLUIDs are an essential component of the rotary DRILLING process used to drill for oil and gas on land and offshore environments. The injection of this nano particle into DRILLING FLUID increases the viscosity levels FLUIDs. In these experiments, the rheological properties of the FLUID including apparent viscosity (AV), plastic viscosity (PV), yielding point (YP), mud cake thickness and FLUID loss (FL) were studied before and after the addition of the nanoclay with different concentrations. In this study, nano particles of clay were used in order to enhance the rheological properties of DRILLING FLUIDs. The results showed nanoclay controls the FLUID loss and is resistant to high temperatures and also FLUID loss. We also found that nanoparticles varying in concentration (0.1 to 1 Wt %) and also size 1, 50 and 500 nm are shown to be effective at improving FLUID rheology.

The present work addresses the validity of no-slip condition for WATER-BASED betonies DRILLING muds. The mud used for the investigation was a suspension of 10% solid (betonies) concentration and its wall slip effects was explored using viscometric techniques. A concentric-cylinder viscometer (model Fann 50C) was used for this purpose. Flow curves obtained using two bobs with different radii indicates that the viscosity measured is a function of the gap distance between the inner and outer cylinders confirming that slip has indeed occurred for this particular mud. A simple technique was explained which enables correcting the flow curve for the slip effects thus resulting in true viscosity function for the test FLUID. Experimental results obtained show that slip velocity scales with wall shear stress inferring that for this particular FLUID, wall slip effects are less sever as compared to other non-Newtonian FLUIDs such as polymer melts and solutions

Amine compounds are believed to have acceptable results regarding their use as clay swelling inhibitor and corrosion inhibitor additives in DRILLING FLUIDs. It is crucial to know the capability of amine compounds to enhance the thermal stability of DRILLING FLUID; herein, a WATER-BASED FLUID composed of biopolymer and other additives as the proper representatives of muds used in the pay zone section of a well is used. In order to enhance DRILLING FLUID thermal stability to 250 ° F (which is about 200 ° F for starch in common DRILLING FLUIDs), the compatibility of four amine compounds (mono ethanolamine, 1, 6-diaminohexane, polyamine, and choline chloride) with three polymers (starch-green, poly-anionic cellulose, and starchhigh temperature) is investigated; one of the named polymers is also chosen to examine its thermal stability performance along with the mentioned amine compounds at 250 ° F. Two percent by volume concentration (2 Vol. %) of the mentioned amines were used. For these purposes, the rheological and filter loss properties were studied. The results showed that the starch-green is almost compatible with four amines. Moreover, mono ethanolamine and 1, 6-diaminohexane acted better in terms of thermal stability at elevated temperatures.