Reduce Fluid Loss Research Articles

Fluid Loss Control in Water Base Mud Using Ferric Oxide Nanoparticles and Local Additives

The success of well drilling operations is heavily dependent on the drilling fluid because drilling fluids cool down and lubricate the drill bit, remove cuttings, prevent formation instability, suspend cuttings and also cake off the permeable formations, thus retarding the passage of fluid into the formation. During drilling operations, the fluid part of the drilling fluid may be lost to the formation, a huge fluid loss lead to higher operational expenses. That is why, it is vital to design the drilling mud to minimize the mud invasion in to formation and prevent fluid loss. This study focused on improving the performance of water base drilling mud by the usage of ferric oxide nanoparticles and local additives such as corn cob powder from zea-mays and coconut husk powder from cocos nucifera as fluid loss control additives in the drilling mud. The laboratory measurements included measuring the filtrate loss using the standard API low temperature low pressure (LTLP) filter test, some properties of the mud such as the mud density and pH were measured using respective apparatus. Also, the filtration properties of water-based nano and local additive drilling fluids under static conditions were investigated. It was seen from the results that the lowest filtrate loss value of 14.4ml occurred for an addition of 1.0g of ferric oxide nanoparticles acting alone as the fluid lost material. Under API standard filtration test at LTLP, more than 70% reduction in fluid loss was achieved in the presence of 0.5 - 1.5 wt% nanoparticles. The results have also shown that the filter cake developed with the nano and local additive mud indicate thin filtration, which implies high potential for reducing the differential pressure sticking problem, as well as reducing formation damage and torque and drag problems while drilling. Nanoparticles (NPs) based drilling mud with specific characteristics is thus expected to play a promising role in controlling the fluid loss and other technical challenges faced with commercial drilling mud during oil and gas drilling Keywords: Coconut Husk, Corn Cobs, Drilling Mud, Ferric Oxide, Filtrate Loss, Fluid Loss Additive, Mud Cake Thickness, Nanoparticles DOI: 10.7176/CER/13-6-03 Publication date: October 31 st 2021

Evaluation of rheological and filtration properties of a polymeric water-based drilling mud in presence of nano additives at various temperatures

Over the past decades, utilizing water-based muds (WBM) in drilling operations has been significantly increased due to their environmental-friendly characteristics. However, the performance of WBM in drilling operations compared to oil-based muds and synthetic-based muds is lower. Hence, some additives (i.e., polymers, nanoparticles (NPs)) have been added to improve WBM’s rheological properties. The objective of this research is to evaluate the impacts of silica (SiO2) and titanium dioxide (TiO2) NPs on rheological and filtration properties of a polymeric-WBM at 25, 50, and 75 °C. The NPs at concentrations from 0.01 to 0.5 wt% were dispersed in the polymeric WBM. The results revealed that by increasing the concentration of SiO2 NPs, the yield point (YP) and gel strength (GS) values of the base mud were increased by approximately 20% at all temperatures, while TiO2 NPs could only increase YP and GS values at 50 and 75 °C, and to a lesser extent than SiO2 NPs. Both NPs also resulted in decreasing of PV values by more than 20% at all temperatures. The lowest amount of PV was achieved at 0.1 wt% for both NPs. Besides that, both SiO2 and TiO2 NPs reduced fluid loss from the polymeric WBM at all applied temperatures. The lowest amount of fluid loss was obtained at 0.1 wt% SiO2 NPs, by roughly 35% reduction. Furthermore, both NPs also resulted in a higher quality mud cake as compared to the base mud. Overall, it can be concluded that SiO2 NPs followed by TiO2 NPs have great potential to improve the rheological and filtration properties of polymeric WBMs at operational conditions.

Application of Hybrid Silicate as a Film-Forming Agent in High-Temperature Water-Based Drilling Fluids.

Effective control of shale swelling and lost circulation using drilling fluid is considered the dominant strategy for maintaining borehole stability, especially drilling operations in deep oil and gas wells. In this work, a hybrid silicate that contains lithium silicate and potassium methyl silicate (PMS) was employed as a film-forming additive to reduce shale hydration and filtration loss in the high-temperature drilling fluid. Scanning electron microscopy (SEM) results revealed that a dense quartz crystal film coating on the shale can be formed in a hybrid silicate solution when the temperature exceeds 150 °C. The in situ-formed film on the shale surface with a thickness of 60–130 μm was composed of fibrous crystalline silica. Furthermore, the aqueous hybrid silicate exhibited enhanced hydration inhibition ability by preventing water invasion of the formation. Aqueous hybrid silicate with a concentration of 0.5–3 wt % lithium silicate and 0.1–0.2 mol/L PMS was first chosen to obtain the optimum concentration according to the hydration inhibition ability and film formation characteristics. The hybrid silicate was added into a drilling fluid formulation applicable in high-pressure and high-temperature conditions, and the rheological characteristics and filtration properties were investigated. The results confirmed that drilling fluids with the addition of hybrid silicate can mitigate variation of viscosity and yield point before and after aging at 180 and 220 °C. Besides, the filtration behavior was also improved by adding hybrid silicate into the drilling fluid. A lower filtration loss was observed at the concentration of 1.0 wt % lithium silicate and 0.2 mol/L potassium methyl silicate, which showed 63 and 50% HPHT fluid loss reduction for unweighted and weighted formulations at 205 °C and 3.5 MPa, respectively. In addition, the drilling fluid featured stable rheological and filtration properties and excellent shale hydration inhibition characteristics when exposed to high temperatures, making it a promising candidate for drilling in deep oil and gas wells.

Finding Solutions for Fibrosis: Understanding the Innate Mechanisms Used by Super-Regenerator Vertebrates to Combat Scarring.

Soft tissue fibrosis and cutaneous scarring represent massive clinical burdens to millions of patients per year and the therapeutic options available are currently quite limited. Despite what is known about the process of fibrosis in mammals, novel approaches for combating fibrosis and scarring are necessary. It is hypothesized that scarring has evolved as a solution to maximize healing speed to reduce fluid loss and infection. This hypothesis, however, is complicated by regenerative animals, which have arguably the most remarkable healing abilities and are capable of scar‐free healing. This review explores the differences observed between adult mammalian healing that typically results in fibrosis versus healing in regenerative animals that heal scarlessly. Each stage of wound healing is surveyed in depth from the perspective of many regenerative and fibrotic healers so as to identify the most important molecular and physiological variances along the way to disparate injury repair outcomes. Understanding how these powerful model systems accomplish the feat of scar‐free healing may provide critical therapeutic approaches to the treatment or prevention of fibrosis.

Experimental Study on the Polymer/Graphene Oxide Composite as a Fluid Loss Agent for Water-Based Drilling Fluids.

The wellbore instability caused by the penetration of drilling fluids into the formation is a vital problem in the drilling process. In this study, we synthesized a polymer/graphene oxide composite (PAAN-G) as a fluid loss additive in water-based drilling fluids. The three monomers (acrylamide (AM), 2-acrylamide-2-methyl-1-propane sulfonic acid (AMPS), N-vinylpyrrolidone (NVP)) and graphene oxide (GO) were copolymerized using aqueous free radical polymerization. The composition, micromorphology, and thermal stability properties of PAAN-G were characterized by Fourier transform infrared (FT-IR) spectroscopy and thermogravimetric analysis (TGA). According to the American Petroleum Institute (API) standards, the influence of PAAN-G on the rheological and filtration properties of bentonite-based mud was evaluated. Compared with PAAN, PAAN-0.2G has more stable rheological properties at high temperatures. The experimental results showed that even at a high temperature of 240 °C, PAAN-G can still maintain a stable fluid loss reduction ability. In addition, PAAN-G is also suitable for high-salt formations; it can still obtain satisfactory filtration volume when the concentration of sodium chloride (NaCl) and calcium chloride (CaCl2) reached 25 wt %. Besides, we discussed the fluid loss control mechanism of PAAN-G through particle size distribution and scanning electron microscopy (SEM).

Developing a Thermally Stable Ester-Based Drilling Fluid for Offshore Drilling Operations by Using Aluminum Oxide Nanorods

Esters were found to be promising alternatives to oil, as a constituent of drilling fluids, due to their biodegradability and bioaccumulation attributes. In this study, we used ethyl octanoate ester (EO) as a low molecular weight synthetic oil for formulating an ester-based drilling fluid (EBDF). Aluminum oxide nanorods (nanoparticles) were introduced as a Pickering emulsion stabilizer. Like the commercial emulsifiers, they showed that they stabilized the invert emulsion drilling fluid in our study. The rheological and filtration properties of the EBDF were tested at normal pressure and three temperatures: low temperature deepwater (LT) conditions of 2.6 °C, normal pressure and normal temperature (NPNT) conditions of 26.8 °C, and elevated temperature conditions of 70 °C. To enhance the stability and filtration properties of the drilling fluid, aluminum oxide nanoparticles (NPs) were used. An optimum concentration of 1 wt% was found to provide superior rheological performance and higher stability than samples without NPs at NPNT, LT, and elevated temperature conditions. Steadier gel rheology was exhibited at elevated temperature conditions, and a slow rate of an increasing trend occurred at the lower temperatures, with increasing NP concentrations up to 1.5 wt%. Filtration loss tests presented a reduction of fluid loss with increasing the NP concentration. The results demonstrate that a reduction of up to 45% was achieved with the addition of 1 wt% NP. These results show that nano-enhancement of ethyl octanoate drilling fluids would suffice to provide a wider range of operational temperatures for deepwater drilling operations by providing better thermal stability at elevated temperatures and maintaining stability at lower temperatures.

Investigation and assessment of neutrophil dysfunction early after severe burn injury

BackgroundExtensive burn injury results in a complex immune response that is associated with mortality and prognosis. Studies on acquired immune and the development of sepsis in burn patients have been reported. However, one of the main cells in innate immune, neutrophil dysfunction in the burn shock stage has not been thoroughly characterized. MethodsNeutrophil chemotaxis, expression of neutrophil surface markers (P2X1 receptor, [P2RX1]), degranulation (myeloperoxidase [MPO], heparin-binding protein [HBP], matrix metalloproteinase-9 [MMP-9] and neutrophil elastase [NE]), oxidative burst capacity, neutrophil extracellular trap (NET) generation, phagocytosis and apoptosis were measured in 18 patients with major burns (≥30% total body surface area [TBSA]) within 48 h after burn injury. In addition, circulating neutrophils and vascular permeability in mice model with 30% TBSA third-degree burns were also observed and investigated. ResultsNeutrophil functions were reduced considerably in burn shock stage, which was characterized by decreased chemotaxis, phagocytosis and abnormal bactericidal function. Increased release of heparin-binding protein (HBP) and the expression of P2RX1 on the neutrophil surface are related to fluid leakage and decreased chemotaxis during burn shock stage, respectively. The combination of HBP concentration in plasma and P2RX1 expression on neutrophils gives a better prediction of neutrophil dysfunction in burn-injured patients. ConclusionNeutrophil dysfunction plays a key role in the development of burn injury. Targeting the restoration of neutrophil function may be a feasible therapeutic intervention to help reduce fluid loss during shock and the severity of subsequent infection.

Determining the Optimum Concentration of Pumpkin Seed Shells as Filtration Control Additive to Water-Based Mud System

Filtrate loss within formations is one of the biggest problems during drilling operations. Therefore, many commercial chemical additives have been used to reduce fluid loss, such as carboxymethylcellulose (CMC) and polyanionic cellulose (PAC), which are expensive and are not environment-friendly substances. This study evaluates the usage of pumpkin seed shells (PSS), which is agricultural waste and at the same time an environment-friendly material, as an additive to the drilling fluid to reduce fluid loss. Six drilling fluid samples were formulated, adding PSS of 250 μm in size at different concentrations (1 wt%, 2 wt%, 3 wt%, 4 wt%, and 5 wt%). The effect of adding PSS on rheological properties and density was recorded and analyzed. Filtration was also studied by using an API LT LP press. The results of the study indicated that the addition of PSS to the drilling fluid has a clear effect on reducing fluid loss. The optimum concentration of PSS was 5 wt%.

A high-temperature and High-Density Environmentally-Friendly Water-Based Drilling Fluids Based on Modified Plant Polyphenols

To improve the high-temperature resistance and density upper limit of environmentally friendly water-based drilling fluids, the fluid-loss reducer EHT-FL and the thinner EHT-TH were developed by modifying plant extracts of natural polyphenol. Two synthesized products were characterized by infrared spectroscopy. In laboratory experiments, the fluid-loss reducer EHT-FL and the thinner EHT-TH exhibited good high-temperature resistance. And the EC50 reached 2.38×105 mg/L and 4.49×105 mg/L, respectively, with no biological toxicity. The medium-pressure and high-temperature/high-pressure fluid-loss of freshwater-based mud with 2.0% EHT-FL are only 7.2 mL and 23.6 mL after aging at 200℃. When the dosage of EHT-TH is 1.0%, the apparent viscosity of high-density water-based drilling fluid (ρ=2.0 g/cm3) after aging at 200℃ decreases from 106.5 mPa·s to 66.5 mPa·s, and the high-temperature thickening phenomenon disappears. Based on the excellent temperature-resistance of EHT-FL and EHT-TH, a high-temperature and high-density (ρ=2.0 g/cm3) environmentally friendly water-based drilling fluid has been developed. This drilling fluid has reasonable rheological and fluid-loss properties. It has high-temperature resistance of 210℃ and resistance to 25% salt contamination, 1% calcium contamination, and 10% inferior soil contamination. EC50 of this drilling fluid is 4.19×104 mg/L, BOD5/CODCr is 29.23, heavy metal content is lower than the standard value, non-toxic, biodegradable. Therefore, this environmentally friendly drilling fluid can meet the drilling needs of deep-wells complex formations.

Addition of Surfactant-Modified Graphene Improves Water-Based Drilling Mud

This article, written by JPT Technology Editor Chris Carpenter, contains highlights of paper SPE 197774, “Improvement in Rheological Features, Fluid Loss, and Swelling Inhibition of Water-Based Drilling Mud by Use of Surfactant-Modified Graphene,” by Azeem Rana and Tawfik A. Saleh, King Fahd University of Petroleum and Minerals, and Mohammad K. Arfaj, Saudi Aramco, prepared for the 2019 Abu Dhabi International Petroleum Exhibition and Conference, Abu Dhabi, 11-14 November. The paper has not been peer reviewed. This paper reports the effect of sodium dodecyl sulfate modified graphene (SDS-Gr) on the rheological features, fluid loss, and swelling inhibition mechanism of clay. The outcomes revealed that the addition of SDS-Gr to traditional drilling mud clearly affects the rheological properties, increasing its suitability for drilling. Moreover, SDS-Gr additive reduces fluid loss by 20% compared with the mud without SDS-Gr.

Development of a Polyacrylamide-Based Mud Formulation for Loss Circulation Treatments

Abstract Loss circulation materials in the last two decades have witnessed a lot of developments and implementations. New technologies and materials are introduced to treat various types of loss zones. However, the success rate is still very low due to many uncertainties in the selection of types and particle size of the bridging materials. In addition, there are many operational restrictions such as the risk of plugging and pumping difficulties when large size of particle is needed, especially in deep-water drilling. In this study, polyacrylamide (PAM) crosslinked with polyethylenimine (PEI) is introduced as polymer-based mud for loss circulation treatment. The PAM/PEI systems have wide applications in water shutoff for high water production zones and are known for their strong gel and exceptional rheological properties. This study provides a rheological method for screening of PAM/PEI-based drilling formulation with optimized molecular weight and concentrations. Comparative analysis of rheology of non-crosslinked and crosslinked polyacrylamide with other drilling fluids additives as well as proper mixing procedures are provided. The results achieved in this study are used as a strong tool to design a polymer-based mud with competitive rheological properties which achieved an 80% reduction in fluid loss when compared with other conventional loss circulation materials.

Synthesis and assessment of a hydrophobically associating heteropolymer in water-based mud

Water-soluble polymers can be used as key ingredients of both drilling fluids for virgin fields and polymer-enhanced oil recovery in underperforming reservoirs. The efficacy of hydrophobically associating heteropolymer (HAH-Polymer) as an agent for petroleum resource recovery was examined in this study. The hydrophobically associating heteropolymer (HAH-Polymer) comprising acrylamide, sodium 2-acrylamido-2-methylpropanesulfonate, hydroxyethyl methacrylate and lauryl methacrylate was synthesized in micellar medium by free-radical polymerization. The hydrophobically associating heteropolymer (HAH-Polymer) was characterised by FTIR and 1H NMR spectral analyses. The effects of temperature, pH and shear on the solution behavior of the HAH-Polymer were also examined. Rheological and fluid loss properties of HAH-Polymer-incorporated water-based drilling fluids were assessed. The HAH-Polymer improved the thermal stability between 25 and 160 °C of the drilling mud and maintained mud fluid loss of 8.4–8.6 cm3 compared with the polymer-free blank of 43.5–107.0cm3. In a salt-contaminated mud, the heteropolymer enhanced rheological properties and significantly reduced API filtration loss to 7.6–8.8 cm3 after hot aging between 25 and 150 °C. Under high temperature–high pressure filtration testing of muds, the HAH-Polymer demonstrated excellent fluid loss reduction by providing about eightfold fluid loss control (14.7 cm3) compared to the polymer-free blank (113.2 cm3) at 150 °C.

Effect of high temperature ageing on TiO2 nanoparticles enhanced drilling fluids: A rheological and filtration study

Design of drilling fluids is critical to the techno-economic success of drilling a petroleum well bore and the present study is a forward step in that direction. Effect of TiO2 nanoparticles on the thermal stability of drilling fluid properties is evaluated using two different mud systems based on polyanionic cellulose (PAC) and hydroxyethyl cellulose (HEC). Drilling fluids were subjected to high temperature rolling conditions at 110 °C and 30 rpm for 16 hours in order to simulate the wellbore environment using a roller oven. Due to 16 h long hot rolling, the API FL values for DFB (base mud), DFP3 (1.0 w/v% PAC) and DFH3 (1.0 w/v% HEC) increased by ~56%, ~18% and ~46% respectively; whereas in presence of 0.5 w/v% nanoparticles respective figures were ~28%, ~16% and ~25%. In case of DFP3, AV at 25 °C was reduced due to hot rolling by ~34% without nanoparticles and by only ~15% in presence of nanoparticles. For DFH3, the percentage reduction in AV at 25 °C due to ageing was ~24% which decreased to ~16% for DFHN (1.0 w/v% HEC and 0.5 w/v% TiO2). It was found that nanoparticles imparted resistance to thermal degradation in rheological and filtration characteristics of drilling fluids. Filter cakes were studied using scanning electron microscopy and showed nanoparticles scattered over the surface of filter cakes which were filling the micro and nano sized gaps in the porous structure of mud cake and reducing the filtration rate. This study shows that using TiO2 nanoparticles along with a conventional fluid loss reducer additive not only enhances the efficacy of that additive but also improves the thermal stability and rheological properties of mud systems.

A new type of experimentally proposed in situ heat/gas clean foam fracturing fluid system

When cold fluid is injected into low-temperature, low-pressure, low-permeability reservoirs containing wax-bearing heavy oil, cryogenic paraffin deposition and heavy oil condensation will occur, thus damaging the formation. Moreover, the formation pressure coefficient is low and the working fluid flowback efficiency is low, which affects the fracturing stimulation effect. Therefore, an in situ heat/gas clean foam fracturing fluid system is proposed. This system can ensure that conventional fracturing fluid can create fractures and carry proppant in the reservoir, generate heat in situ to avoid cold damage, reduce the viscosity, and improve the fluidity of crude oil. The in situ heat fracturing fluid generates a large amount of inert gas while generating heat, thus forming foam-like fracturing fluid, reducing fluid loss, improving proppant-carrying performance, improving gel-breaking performance, effectively improving crack conductivity, and is clean and environmentally friendly. Based on the improved existing fracturing fluid system, in this paper, a new type of in situ heat fracturing fluid system is proposed, and a system optimization evaluation is conducted through laboratory experiments according to the performance evaluation standard of water-based fracturing fluid. Compared with the traditional in situ heat fracturing fluid system, the fracturing fluid system proposed in this study generates a large amount of inert gas and form foam-like fracturing fluid, reduces fluid loss, enhances the proppant-carrying capacity and gel-breaking performance, improves crack conductivity, the gel without residue and that the gel-breaking liquid is clean and harmless.

Styrene butadiene resin/nano-SiO2 composite as a water-and-oil-dispersible plugging agent for oil-based drilling fluid

In this paper, styrene butadiene resin/nano-SiO2 (SBR/SiO2) composite was synthesized by the continuous emulsion polymerization method, which was used as a plugging agent for oil-based drilling fluid (OBDF) to enhance plugging efficiency in shale formations. The characterization of SBR/SiO2 was measured by Fourier transform infrared spectroscopy, thermal stability and scanning electron microscopy. The results implied that the structure of SBR/SiO2 was consistent with design. The dispersion of SBR/SiO2 in water and mineral oil were studied by particle size distribution and rheological analysis. The results indicated that SBR/SiO2 can be dispersed in water and mineral oil simultaneously, while most normal OBDF plugging agents can only be dispersed in water or mineral oil. Since OBDF is a water-in-oil emulsion, when the plugging agents can be dispersed in two continuous phases, the plugging efficiency can be maximized. And it’s the first time to explain plugging ability from dispersion perspective and produce the plugging agent for OBDF which can be dispersed in two phases. Then the plugging ability was evaluated by filtration volume, porosity physical adsorption instrument (BET), and pressure transmission test. The results showed that SBR/SiO2 can enter into the nanopores of shale formations and significantly reduce fluid invasion, thereby improving wellbore stability. Finally, the dispersion and plugging mechanism of SBR/SiO2 were analyzed. This study might provide an avenue to solve the wellbore instability and reservoir damage owing to OBDF during the drilling process by adding the plugging agent which can form a dense filter cake and reduce fluid loss in shale formations.

Controlling Shale Swelling and Fluid Loss Properties of Water-Based Drilling Mud via Ultrasonic Impregnated SWCNTs/PVP Nanocomposites

Wellbore instability due to shale swelling and fluid loss of drilling mud is the main challenge faced by the oil and gas industry. Herein, we successfully demonstrated the positive impact of newly developed single-walled carbon nanotubes/polyvinylpyrrolidone (SWCNTs/PVP) nanocomposites on the drilling efficiency of water-based muds (WBMs). By adopting a standardized sonication technique, we achieved highly dispersed and uniform distribution of single-walled carbon nanotubes (SWCNTs) within the matrix of polyvinylpyrrolidone (PVP). SWCNTs provided the required mechanical strength and hydrophobicity, while PVP acted as a binder, filler, and dispersion medium. The surface morphology of shales was compared before and after modification with SWCNTs/PVP nanocomposites. The moisture adsorption/repellent characteristics of the shales were predicted by Fourier transform infrared (FTIR) spectroscopy. The dispersion stability of synthesized SWCNTs/PVP nanocomposite with bentonite clay in the presence of water was also recorded for 24 h. The drilling mud modified with 5-SWCNTs/PVP nanocomposite demonstrates 23% reduction in fluid loss. The inhibition stability and swelling rate of shales were systematically investigated and compared with water, KCl, unmodified mud, and commercial shale inhibitor. The comparison indicates that the modified drilling mud having 5-SWCNTs/PVP composite showed the highest dispersion recovery (89.5%) and the lowest swelling rate (21.6%). The synthesized nanocomposite not only forms a protective layer on the shale surface to hinder the access of water but also offers structural stability to the drilling mud. Improved swelling inhibition, fluid loss control, and long-term stability of shale against reactive fluid, suggested that the modified WBM can be effectively utilized to control wellbore instability during drilling operations.

Investigation of LCM soaking process on fracture plugging for fluid loss remediation and formation damage control

When drilling through naturally fractured reservoirs, the remediation of drill-in fluid loss needs to be designed by taking both fracture plugging and formation damage into account. Lost circulation materials (LCMs) should be implemented efficiently to minimize the solid-laden fluid invasion into the fractures during the development of fracture plugs. This study investigated the effects of three LCM deployment factors: injection rate, soaking time, and soaking pressure, on the total fluid invasion volume and plug breaking pressure. Full factorial experimental design and statistical analysis were conducted to study the statistical significance of each factor. Scanning Electron Microscope (SEM) and Micro Computed Tomography (MicroCT) were applied to visualize the plug structures for the understanding of the soaking effects.Different combinations of LCMs were tested in a permeability plugging apparatus with a slotted disk. For granular LCM mixtures, the soaking pressure and time did not have a significant impact on total fluid invasion volume or ultimate plug breaking pressure. For mixtures blended with fibrous LCMs, longer soaking time contributed to reducing fluid loss and increasing plug breaking pressure. A lower LCM pill injection rate led to less fluid invasion upon the establishment of an effective seal. The SEM and MicroCT images indicated that a longer soaking time could lead to a less porous and strengthened plug structure.The results and conclusions from this study provide new insights into the identification of optimal LCM implementation scheme with better formation damage control.

Synthesis and properties of a betaine type copolymer filtrate reducer

With the exploitation of ultra-high temperature deep wells, the fluid loss reducer as the core treatment agent of drilling fluid, in addition to ensuring the fluid loss performance, it needs to have both high temperature and high salt resistance and certain inhibition. Thus, N-(3-dimethylallyl)methacrylamide and 1,3-propane sultone were used to synthesize a betaine-type zwitterionic functional monomer named DMAPMAS. A zwitterionic copolymer PADAN as a fluid loss reducer for drilling fluids was prepared by attaching 2-acrylamide-2-methylpropanesulfonic acid, N-vinylpyrrolidone and synthetic DMAPMAS to the main chain of acrylamide via aqueous solution free radical polymerization. It not only has great thermal but has good fluid loss and inhibition performance. In addition, the addition of PADAN can effectively improve the particle size distribution of the drilling fluid system. The combination of PADAN and sulfonated polymer SMC, SMP-II and SPNH has the effect of reducing the fluid loss of drilling fluid. Moreover, it has good adaptability to a variety of drilling fluid systems. Applied to the sulfonation drilling fluid system and the polysulfide KCl drilling fluid system, it has the significant effect in fluid loss reduction and less impact on the rheological properties to adapt to various drilling fluid systems.

A novel zwitterionic quaternary copolymer as a fluid-loss additive for water-based drilling fluids

ABSTRACT Wellbore instability and formation collapse are crucial issues in the process of well excavation in the oil industry under extreme high temperature conditions. A novel zwitterionic quaternary copolymer (PDANV) of 4-vinylpyridine (VP), N, N-dimethylacrylamide (DMAA), 2-acrylamido-2-methylpropane sulfonic acid, N-vinylcaprolactam (NVCL) was synthesized in aqueous solution by free radical copolymerization reaction. The structure of PDANV was characterized by Fourier transform infrared spectroscopy (FT-IR), nuclear magnetic resonance (1 H NMR), and the results indicated that ideal product are obtained. Thermal stability of PDANV was revealed by thermogravimetric analysis (TGA) and result showed that thermal degradation of PDANV mainly happened over 301°C. Simultaneously, PDANV was prepared to further evaluate its effect on rheological and filtration properties of water-based drilling fluids (WBDFs). The results showed that the fluid loss (FLAPI) of PDANV/WBDFs was only 3.4 mL, 6.0 mL before and after hot rolling at 260°C for 16 h, respectively. Compared with the 19.2% and 57.9% reduction of traditional fluid-loss additives CMC and Driscal, the fluid-loss reduction rate of PDANV/WBDFs was 87.5% in ultra-high temperature environment. Additionally, PDANV performed satisfactorily with great properties in WBDFs even at high concentration of salts and calcium. Therefore, it can be used for applications where the PDANV is subjected to certain harsh environments, such as extreme salinity and ultra-high temperature conditions.

Experimental investigation of the application of Eucalyptus bark to prevent lost circulation in pay zones with acid dissolution capability

Loss of drilling fluid is a common problem during the drilling of wells and it restricts the appropriate functionality of muds. Drilling fluid loss significantly increases drilling costs and non-productive time as well as the drilling operation risks. Various investigations have been carried out in order to find appropriate mud additives that either block fractures and pores or reduce fluid loss by improving the fluid rheology. Cheap, environmentally friendly and effective additives are still required by the drilling industry. Hence, the application of available materials in each region, to produce appropriate additives, is a challenge for the oil industry. In this study, Eucalyptus Camaldulensis (EUC) bark powder has been chosen as a new, fibrous, cheap, environmentally friendly and available material to control fluid loss, particularly in southern Iran. Different characterization tests, such as acid dissolution and fluid loss control, were carried out to study the performance of the new proposed additive. Removal by hydrochloric acid and sulfuric acid were studied at various acid concentrations and temperatures. Dynamic fluid loss was also measured at different EUC concentrations. Our study showed that EUC powder can reduce the final fluid loss by 88–97%, the initial fluid loss by 45–66%, and the total loss by 87–94%, which is a satisfactory level.