Filtration Loss Research Articles

Study of Rheological Properties of Water-based Drilling Fluid in the Well Strength (Using Alumina Nanoparticles)

Abstract Wellbore stability is of one of challenges in drilling industry. Shale formation is of one of the most problematic rocks during drilling because the rock has very low permeability and very small pores (nanometers). In this study, the viability of the Alumina nanoparticles in Water-Based Mud (WBM) is assessed. The effect of Alumina nanoparticles (alpha and gamma) as mud additives to improve the rheological properties in water- base drilling fluids are experimentally investigated. The Alumina nanoparticles has specific chemical and physical properties such as: high compressive strength, high hardness, high thermal conductivity, these properties improve the rheological properties of water base drilling fluid, reduce filtration loss and meet environmental regulations. The results of experiments indicated that Alumina nanoparticle are improving rheological properties such as: yield point (YP), gel strength (GEL 10s, Gel 10min) of water- base drilling, that can be used to improve the rheological and filtration properties of drilling fluids. The experimental data showed that, Alumina nanoparticle as a Nano additive, possessed excellent properties such as thermal stability, rheology enhancing, fluid loss control and lubrication. Also, it could plug the shale formation effectively and improve the pressure bearing capability of formation significantly. In addition, Alumina nanoparticles reduced 60% API/HPHT fluid loss by 60% in comparison with blank sample. The most striking feature is that shale integrity improved by Nano fluid between 60 and 70 percent in comparison with blank sample. Also, data experimental of CT Scan are shown that the filter cakes formed by each of the Nano-drilling fluid samples with alpha alumina and gamma alumina base are more cohesive and cause an integrated filter cake on the well.

Development and Application of a Novel Green Water-Based Drilling Fluid

In response to the technical and environmental protection requirements of water-based drilling fluids, this study independently developed a series of green supporting treatment agents for water-based drilling fluids such as the green loss reducer HB-1, green inhibitor HB-2, and green lubricant HB-3, etc., and proposed a green water-based drilling fluid system (HBDF) with good comprehensive performance. The proposed system has a heat resistance of 150°C, a HTHP (high temperature and high pressure) filtrate loss of 12 mL, a biological toxicity EC50 value greater than 105 mg/L, and a biodegradability BOD5/CODCr value of 16.2%. Now the developed HBDF system has been applied in more than 10 wells in SL oilfield, and the field application results show that the proposed HBDF system has stable rheological and filtrate loss performance, good anti-pollution ability, and easy and simple maintenance operations; after drilling, the biological toxicity of the drilling fluids can meet the environmental protection requirements, which has provided a technical reference for the research of green drilling fluids and the green development of SL Oilfield.

Evaluation of environment friendly micro-ionized litchi leaves powder (LLP) as a fluid loss control agent in water-based drilling fluid

This work investigates the efficacy of a biodegradable natural product, litchi leaves powder (LLP) as a filtration loss control agent in the water-based drilling fluid formulations. In order to evaluate the potential of litchi leaves powder (LLP), a strict protocol of experimentations according to API (American Petroleum Institute) standard has been followed. The experimental outcome showed that before hot rolling and after hot rolling of mud samples at 100 °C it was observed that 3–5% Concentration of LLP significantly increased the rheological parameters such as PV, YP and gelation of drilling fluid as compared to reference mud. Also, LLP reformed the filtration loss control characterization, suggesting a better biodegradable fluid loss reducing agent. After hot rolling at 100 °C for 18 h, the water-based drilling fluid with LLP as an additive showed a marked reduction in filtration control property as compared to reference Mud (RM). Experimental results concluded that 5% concentration of LLP significantly reduced the filtration loss of drilling fluid by 70.6% as compared to reference mud under the influence of 100 psi pressure. However, the conventional fluid loss additive CMC (LVG) reduced the filtration loss by maximum 67.5% as compared to reference mud. Therefore, LLP can be used as an alternative to CMC (LVG) in water-based drilling fluid with a maximum subsurface temperature of 100 °C.

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.

Research and Application of Evaluation Methods for Functional Characteristics of Oil-Based Drilling Fluid in Shale Gas Wells

Intelligent unconventional reservoir optimal production control technology is a comprehensive technology, involving geology, reservoir simulation, and efficient drilling and completion. Efficient drilling and completion provides a flow channel for unconventional oil and gas exploitation and a wellbore with good integrity for reservoir transformation, which is an important link in the efficient development of unconventional oil and gas. The application of industry standard method to evaluate the performance of oil-based drilling fluid has the problem of poor correlation. It cannot reflect the difference of performance among oil-based drilling fluid systems, which lacks the significance for field construction. Based on shale expansion, rolling dispersion experiment, and microporous membrane filtration loss test, the physicochemical mechanism of borehole wall instability in shale formation was investigated. The evaluation methods of shale lubrication, antiaccretion test, slake durability, buck hardness test, etc. are put forward, and the formula of oil-based drilling fluid is optimized. The lubrication and antiaccretion experiment method can effectively and intuitively characterize the cleaning and lubrication effect of drilling fluid on drilling tools. The slake durability evaluation method simulates the collision between drill cuttings and the drill string and well wall. The bucking hardness experiment is through testing the cuttings and the hardness change after drilling fluid action reflects its inhibitory effect. The new methods were used to evaluate the oil-based drilling fluid used in 4 wells in the Changning block. It was found that the drilling fluid of CN209H2 well adhered to the steel column with at least 0.41 g of cuttings; the recovery rate of the drilling fluid resistance of CN209H1 was up to 87.70%, and YX1200 oil-based drilling fluid plugging agent was selected through the microporous membrane experiment. In the process of drilling the well CN209H5, the new oil-based drilling fluid formulation improved the lubrication performance by 44%, accompanied by 95.48% recovery rate and less than 10 mL HTHP fluid loss at the same time. The research results show that the oil-based drilling fluid system optimized according to the new method can significantly inhibit shale hydration and dispersion and can effectively solve the problem of unstable performance of traditional oil-based drilling fluids in the Changning block.

Bentonite Suspension Filtration and its Electro-Kinetics in the Presence of Additives

Abstract Invasion of fluids into porous media during drilling can lead to irreparable damage and reduced well productivity. Hence, minimizing the filtration loss of the drilling fluid into the formation is very important. The stability of colloidal suspensions plays a crucial role in controlling the interfacial forces and consequently on minimizing the filtration. The zeta potential is an indicator of the stability of colloids with respect to their electrostatic interactions. In this study, the rheological properties of bentonite suspensions are investigated with and without additives. The starch and CMC were used as additives to enhance the rheological properties of bentonite. The effects of these additives on the drilling fluid filtration were examined. Zeta-potential, viscosity, gel strength and yield point were measured to characterize the extent to which control of the filtration loss of the drilling fluids can be achieved. The zeta-potential and the amount of filtration loss of water-bentonite suspensions were correlated. Finally, the results showed that the addition of either starch or carboxymethyl cellulose (CMC) enhances the filtration properties of water-bentonite suspensions.

Reparameterization of static filtration model of aqueous-based drilling fluids for simultaneous estimation of compressible mudcake parameters

To mitigate the fluid invasion and the loss of circulation, drilling fluids are designed to provide a thin mudcake with low permeability. Among the many methods of determining the mudcake properties, the absence of proper procedures related to the estimation of mudcake parameters that also consider the experimental uncertainties is noticed. Besides, the non-Newtonian rheological behavior in filtration and its consideration in resistive force modeling is still lacking in the literature. This paper proposes a new methodology of parameter estimation using the particle swarm optimization technique with a modification of the classic model approaches considering the non-Newtonian fluid filtration theory, including the fluid phase rheological behavior. Static filtrations were performed in an HTHP filtration cell with non-Newtonian suspensions with concentrations like those used in actual drilling processes. The internal structure of the mudcakes was studied by SEM images. A reparameterization of the static filtration model was proposed for the simultaneous estimation of precise and uncorrelated parameters: filter resistance, permeability, and compressibility of the mudcakes, considering two different methodologies, Method I – classic and not advisable - and Method II – rigorous statistical process and pressure-dependent filtration properties. As shown in this research, the confidence intervals for all parameters obtained by Method II were narrow with significative statistical meaning, at a confidence level of 95%, and close to those obtained by other authors. Also, the reparameterization procedure removed the parametric correlation between the mudcake permeability and compressibility, resulting in parameters with null correlation. The numerical solution does not lead to a high computational cost and could be installed in an onboard control device to predict online filtration loss, providing valuable pieces of information in oil drilling processes.

The swelling effect of sodium-bentonite as an additive in water-based drilling sludge with different concentration of polyamine inhibition

A highly reactive sludge on drilling progress has become a common problem. The problem will cause swelling clay or high filtration loss. With a risk of swelling appearance and too much filtration loss that may cause, sodium-bentonite is widely used in drilling sludge to give more viscosity and optimal ability to hold and lift the cutting inside the borehole. It contains mostly montmorillonite like particles of sodium that overpower the iolite content inside it. Polyamine as an inhibitor to the clay can infiltrate into the bentonite c-spacing, which is a gap between two layers of bentonite structure. A test has been conducted to measure the effect of polyamine inhibition inside a water-base sludge formulation x that is previously inhibited with sodium-bentonite. These tests were conducted using a number of instruments such as API Filtrate loss, swell meter test, retort oven, and Vann vg meter with API Standard procedure. The result provides a distinctive conclusion about how the rheological elements react toward the polyamine existence with different concentrations (4gr-10,5gr) inside the sludge. This research also reveals that the sludge durability is different between room temperature and high temperature (300°F).

Preparation and performance analysis of bisamido-based cationic surfactant fracturing fluid for coal seam water injection

Coal seam water injection fracturing can achieve the gap formation of the coal seam and increase the porosity of the coal seam. The water injection fracturing fluid wetting the coal body can wet the coal body in advance, reducing the generation of coal dust during coal mining, as well as play a preventive role in many coal mine accidents and optimize the safety state of the coal mine. To further improve the water injection efficiency of the coal seam. In this paper, erucic acid, N,N-dimethyl-1,3-propanediamine and epichlorohydrin were used as raw materials to synthesize a bisamido cationic surfactant under acidic conditions, and mixed with a KCl solution to prepare a clean fracturing fluid that can be used in the water wetting of a coal seam. The functional groups and microstructure changes of the product are observed by FTIR and SEM. Related performance experiments show that the product has the advantages of good shear stability viscosity, low filtration loss, good gel breaking performance and strong wettability. The analysis of the cleanability shows that the gel breaking liquid has a low residue content and good compatibility. Therefore, the product is an ideal clean fracturing fluid for water injection fracturing of coal seam.

Interaction of lubricants on the rheological and filtration loss properties of water-based drilling fluids

Drilling fluids show significant role in the success of drilling operations of oil and gas well. Lubricating and rheological properties are important for efficient drilling leading to improved oil/gas production. The current work deals with assessing the lubricating properties of 16 different water-based drilling fluids using five lubricants and scrutinizing their consequence on the rheology of the mud, filtration properties and mud cake thickness. Experiments are carried out at 90 °C by hot rolling the drilling fluids. After aging, the rheological, API HPHT filtration loss, and lubricating properties of mud are measured at ambient conditions. The results have been discussed in relation to the effect of lubricants on the recovery performance of oil and gas from reservoir. Increased lubrication provides enhancement in rate of penetration, with improved drilling efficiency into the oil and gas reservoir rock formation. The HPHT filter press test showed permissible fluid loss for all the drilling fluid systems containing lubricants with thin and impermeable filter cake formation. The thin mud cake and less fluid loss into the reservoir indicate less reservoir damage while drilling thus indicating enhanced recovery of oil and gas during production operation.

Oil-Based Drilling Fluid Plugging Method for Strengthening Wellbore Stability of Shale Gas

Finding out the reasons for wellbore instability in the Longmaxi Formation and Wufeng Formation and putting forward drilling fluid technical countermeasures to strengthen and stabilize the wellbore are very crucial to horizontal drilling. Based on X-ray diffraction, electron microscope scanning, linear swelling experiment, and hot-rolling dispersion experiment, the physicochemical mechanism of wellbore instability in complex strata was revealed, and thus, the coordinated wellbore stability method can be put forward, which is “strengthening plugging of micropores, inhibiting filtrate invasion, and retarding pressure transmission.” Using a sand bed filtration tester, high-temperature and high-pressure plugging simulation experimental device, and microporous membrane and other experimental devices, the oil-based drilling fluid treatment agent was researched and selected, and a set of an enhanced plugging drilling fluid system suitable for shale gas horizontal well was constructed. Its temperature resistance is 135°C and it has preferable contamination resistibility (10% NaCl, 1% CaCl2, and 8% poor clay). The bearing capacity of a 400 μm fracture is 5 MPa, and the filtration loss of 0.22 μm and 0.45 μm microporous membranes is zero. Compared with previous field drilling fluids, the constructed oil-based drilling fluid system has a greatly improved plugging ability and excellent performance in other aspects.

Minimizing the filtration loss of water-based drilling fluid with sustainable basil seed powder

Filtration control is important to ensure safe and high efficient drilling. The aim of the current research is to explore the feasibility of using basil seed powders (BSPs) to reduce filtration loss in water-based drilling fluid. The effect of BSP concentration, thermal aging temperature, inorganic salts (NaCl and CaCl2) on the filtration properties of bentonite/basil suspensions was investigated. The filtration control mechanism of BSP was probed via water absorbency test, zeta potential measurement, particle size distribution measurement, and filter cake morphologies observation by scanning electron microscope. The incorporation of BSPs into the bentonite suspension generated acceptable rheology below 1.0 w/v%. The BSPs exhibited effective filtration control after thermal aging at 120°C, but less efficiency at 150°C. After thermal aging at 120°C, the bentonite suspension containing 1.0 w/v% BSPs could resist NaCl and CaCl2 pollution of 5.0 w/v% and 0.3 w/v% respectively. Besides general filtration control behaviors, the exceptional water retaining capability formed by numerous nanoscale 3D networks in the basil seed gum and considerable insoluble small particles in BSPs might further contribute to the filtration control. The excellent filtration properties bring basil seed a suitable and green candidate for the establishment of high-performance drilling fluids.

Formulation and performance evaluation of polymer-thickened supercritical CO2 fracturing fluid

Compared with conventional water-based fracturing fluid, supercritical CO2 fracturing fluid has the characteristics of inhibiting water sensitive damage and improving flowback efficiency. In view of the problems of low viscosity, poor sand-carrying performance and large filtration loss capacity of pure supercritical CO2, a supercritical CO2 fracturing fluid system had been prepared: 5% polydimethylsiloxane +5% kerosene +90% supercritical CO2. The rheological property, sand-carrying property, filtration loss property, core damage property and wetting inversion property of the system were systematically studied through performance evaluation experiments. At 325 K, the viscosity of the system can reach 4.67 mPa s, which was 54.26 times higher than that of pure supercritical CO2. The performance evaluation showed that the system had a good rheological property. The sand-carrying capacity was improved by 38.17%, and the filtration loss coefficient was decreased by 71.71% at most. The interaction results between CO2 and reservoir showed that the system could effectively increase the porosity and permeability of the core. For ultra-low permeability sandstone core, the porosity was increased by 7.71%, the permeability was increased by 115.20%. While for shale core, the porosity was increased by 6.99%, permeability was increased by 102.44%. At the same time, the system can change the core wetted by water phase into a neutral wetted one which was favorable for oil and gas flow. This system is expected to be further studied in oilfield applications.

Application of Response Surface Methodology and Box-Behnken Design for the Optimization of the Stability of Fibrous Dispersion Used in Drilling and Completion Operations.

Fibers are extensively used as a fluid additive in the oil and gas industry to improve hole-cleaning performance, control fluid filtration loss, and enhance hydraulic fracturing effectiveness. Generally, a small amount of fiber is dispersed in the base fluid to achieve the desired results without increasing the viscosity of the base fluid. Nevertheless, sustaining a uniform fiber dispersion can be challenging under wellbore conditions, which is essential for fibers’ functionality. Consequently, a better understanding of fiber suspension or stability in base fluids is necessary for their efficient utilization in drilling and completion operations. In this study, response surface methodology (RSM) and box–behnken design (BBD) are used to investigate the stability of fiber in polymeric base suspensions, including carboxy methyl cellulose (CMC), polyacrylamide (PAM), and xanthan gum (XG). The BBD of three factors was selected to observe the influence of polymer concentration, fiber concentration, and temperature on fibrous suspension stability, with three levels of design factors (low, mid, and high) and two fiber aspect ratios (3 and 12 mm fibers). The base fluid polymer concentration ranged from 1 to 8 vol %, fiber concentration ranged from 0.01 to 0.08 wt %, and the temperature was varied from 25 to 80 °C. The stability measurements were analyzed using Minitab, subsequently, evaluating the factors’ impact and interactions and determining the optimum conditions for the stability of the fibrous suspensions. The results predicted by the developed model were in good agreement with the experimental results R2 ≥ 0.91–0.99. The sensitivity analysis showed that base fluid polymer concentration is the most significant factor affecting fibrous suspension stability. At high polymer concentrations, fiber concentration and temperature effects are minimal, while the temperature effect on the stability was observed at low concentrations (e.g., low suspension viscosities). The fiber aspect ratio indirectly affects system stability. Long fibers have a better tendency to entangle and form a structured network, which in turn hinders the buoyancy that induces individual fiber migration. On the contrary, short fibers do not form a network, allowing them to easily migrate to the surface and agglomerate at the top layer (unstable region). Optimization results revealed that suspensions with viscosities above 50 mPa·s are sufficient to maintain the stability of the suspensions at ambient (25 °C) and elevated (80 °C) temperatures.

Experimental Investigation of Aloe-Vera-Based CuO Nanofluid as a Novel Additive in Improving the Rheological and Filtration Properties of Water-Based Drilling Fluid

SummaryDrilling technology in petroleum engineering is associated with problems such as high fluid loss, poor hole cleaning, and pipe sticking. Improvement of rheological and filtration properties of water-based drilling fluids (WDFs) plays a major role in resolving these drilling problems. The application of nanotechnology to WDF in the recent past has attracted much attention in addressing these drilling operations problems. In the present work, we investigate the application of natural aloe vera and CuO nanofluids combined as an additive in WDF to address the drilling problems. The nanofluids of three different concentrations of CuO nanoparticle (0.2, 0.4 , and 0.6 wt%) with aloe vera as a base fluid are prepared for this study by adopting a two-step method. The prepared nanofluids are characterized by their particle size and morphological characteristics. Conventional WDF (DF.0) is synthesized, and the prepared aloe-vera-based CuO nanofluid is added to the WDF to prepare nanofluid-enhanced water-based drilling fluid (NFWDF) of different concentrations of nanoparticles, namely, 0.2 , 0.4, and 0.6 wt%. The prepared drilling fluid mixture is then characterized for its rheological and filtrate loss properties at various temperatures. Thermal stability and aging studies are performed for both WDF and NFWDF. The experimental results are then modeled using rheological models. The results reveal that aloe-vera-based CuO nanofluids improve the thermal stability and rheological properties of drilling fluid and significantly decrease the American Petroleum Institute (API) filtrate. Viscosity for WDF shows an approximately 61.7% decrease in heating up to 90°C. Further, the hot roll aging test causes a 63% decrease in the viscosity of WDF at 90°C. However, the addition of aloe-vera-based CuO nanofluids is found to aid in recovering the viscosities to a great extent. The fluid loss values before hot rolling are observed to be 6.6 mL after 30 minutes, whereas fluid loss values for the NFWDFs are found to be 5.9, 5.4, and 4.6 mL, respectively. The fluid loss value after hot rolling for the WDF is found to be 10.8 mL after 30 minutes, whereas fluid loss values for the NFWDFs are found to be 9.2, 8.5, and 7.7 mL, respectively. The rheological performance data of NFWDF project a better fit with the Herschel-Bulkley model and suggest improvement in rheological and filtration properties. There has been limited research work available in understanding the impact of aloe-vera-gel-based nanofluids in improving the performance of WDFs through the improvement of its rheological and filtration properties. This study aims to exploit the property of native aloe vera and CuO nanofluids combined together to enhance the rheological and filtration properties of WDF by conducting the tests both before and after hot rolling conditions. This study acts as an important precursor for developing novel additives for WDF to improve its rheological and filtration properties. This study is also expected to benefit the industry and solve the major challenges in deep-well drilling operations and high-pressure and high-temperature (HPHT) drilling operations.

Study of Environmentally Friendly Wild Jujube Pit Powder as a Water-Based Drilling Fluid Additive.

The development of offshore oil and gas requires environmental protection during the drilling process. However, the existing drilling fluid additives cannot form an efficient environmentally friendly drilling fluid system. At the same time, some environmentally friendly drilling fluid additives cannot be widely used due to their high cost and complicated production process. In this paper, a natural material named wild jujube pit powder (WJPP) was used to improve the performance of the drilling fluid for the first time. The viscosity, shear force, shear thinning, rheology, filtration loss, and lubrication properties of the drilling fluid are discussed. By means of microstructure analysis, infrared spectroscopy, thermogravimetric analysis, and particle size analysis, the properties of WJPP and the drilling fluid system containing WJPP (i.e., rheological property, lubrication property, and filtration loss property) were studied. The results show that the microscopic appearance of WJPP was spherical, fibrous, block, and flake, the thermal decomposition temperature was 273.9 °C, and the suspension of WJPP was slightly acidic. WJPP can increase the viscosity, reduce the filtration loss, enhance the shear thinning and thixotropy, and reduce the lubrication coefficient of the drilling fluid. With the decrease in the particle size of WJPP, the shear thinning and thixotropy of the drilling fluid are enhanced, the viscosity and shear force increased, and the filtration loss and lubrication coefficient decreased. With the increase in the dosage, the shear thinning of the drilling fluid was enhanced, the filtration loss and coefficient of friction decreased, the viscosity and shear force increased, while the thixotropy did not change significantly. The microstructure test of mud cake showed that WJPP could form a grid structure. Combined with the blocking action of particles, the structure could prevent water molecules from passing through to reduce the filtration loss. WJPP can improve the rheological property, filtration property, and friction property of the drilling fluid, which has certain application prospects.

Study on wellbore instability mechanism and drilling fluid optimization of Yingsha block in southwest Tarim Basin

The southwest area of Tarim has good potential for exploration and development, but the geological conditions of Yingsha block are complicated and complex conditions occurred frequently in drilling operations. There were 11 times lost circulation, which ranged from N2a to E1a and the lithology ranged from mudstone and sand-mudstone interbeds to gypsum rock, and the drilling cycle is up to 719 days, which seriously restricts the exploration and development of oil and gas resources. In this paper, the rock mineral composition and physical and chemical characteristic profiles of the whole well have been established for the well drilled in this area. The characteristic profiles show that quartz (21.4%~57.4%) and clay minerals (17%~44.9%) are the main layers in the lower strata (5069 m-7015 m) drilled in Yingsha. The clay minerals are dominated by illite (58%~85.75%) without smectite. The highest proportion of illite/smectite formation is 25%, the highest expansion rate is 23.87%, and the lowest recovery rate is 3%. Therefore, the stratum has strong hydration and dispersion characteristics. The average porosity of 4064 m-6666.5 m is 1.86%-6%, and the formation cracks are well developed. The wellbore instability mechanism in Yingsha is the good physical property of the sandstone, the development of cracks and micro-cracks in the lower strata, the broken strata, and the strong hydration and dispersion ability. The performance evaluation of KCL-Polysulfonate drilling fluid used in Yingsha shows that the recovery rate increases to more than 80% when the amount of KCL is 7–10%. With the introduction of paraffin nano-emulsion, the filtration loss is reduced by 30%, and the inhibition and plugging performance of drilling fluid is further improved.

An Experimental Study on optimizing the particle size distribution of bridging agents in drilling fluids

Managing lost circulation has always been a serious challenge in the oil industry. This situation becomes further complicated when shale formation is involved. Particulate lost circulation materials (LCMs) have been used to prevent the drilling fluid from entering fractured, cavernous, or high-permeability formations for many years. However, existing LCMs are inefficient in terms of size and application methods in solving severe-to-total losses in shales due to the uncertainty of particle size distribution (PSD) in drilling fluids. This study focuses on an experimental method optimizing the PSD of solid particles in the drilling fluid at high temperature and pressure. An orthogonal experiment of L9 (3)4, including four factors and three levels, was designed to investigate the relationship between the PSD of solid particles and filtration loss. Results indicate that the orthogonal design method contributes to the optimization of the PSD of solid particles in the drilling fluid and reduce the test time and experimental workload during the drilling fluid process in the design stage. In addition, a polynomial relationship between the cumulative filtration loss and D90 or D50 is verified experimentally in this study. This study will remarkably benefit the drilling technologists in resolving the issue of lost circulation.

СОВЕРШЕНСТВОВАНИЕ РЕЖИМА ЭКОНОМИИ ДРЕНАЖНО – СБРОСНОГО СТОКА НА РИСОВЫХ СИСТЕМАХ В МАЛОВОДНЫЕ ГОДЫ

The article addresses the issues of improving the regime of saving drainage and discharge water on rice systems in low-water years. The best conditions for rice development are created when there is a layer of water on the soil surface. Due to the presence of a layer of water and its regulation on the lands of rice systems, an optimal reclamation state is maintained. Volumes of supplied and withdrawn water from rice systems depend on relief, hydrogeological and hydrological conditions. The greatest impact on the volume of water supply and runoff is the spring flood, which falls on May - June months, which causes flooding of rice fields. The volume of drainage and discharge of rice irrigation systems of the North Caucasus is 20-75% of water supply. For rice systems located in the dryless and weakly drained zones of the Volga Delta, this volume is significantly larger and reaches 120% of the water supply. Significant filtration from the channels has a great influence on the regime of groundwater, leads to an increase in the level of groundwater in the channel zone, causing flooding, waterlogging and salinization of the territories adjacent to the channels, up to their withdrawal from agricultural use. Filtration losses from the inter-farm and intra-farm network depend on the nature of its clothes, the periodicity of work, the type of soils in which this network is laid, and the degree of turbidity of irrigation water. Depending on the different combination of these factors, the efficiency varies widely: from 0.40 to 0.97, determining a large range of losses for filtration and, accordingly, groundwater supply. In the course of the conducted studies, the regimes for improving the mode of saving drainage and discharge water on rice systems were justified precisely in low-water years. The use of various types of watering on checks and sprinkling with moisture-charging watering contributes to the removal of salts from the upper layers of the soil profile when mineralizing groundwater up to 5 g/l, and watering is desalinating.

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%.