Low Permeable Filter Cake Research Articles

Leakage through a circular geomembrane hole overlain and underlain by silty sand tailings

Experiments are conducted to investigate leakage through circular GMB holes overlain and underlain by both tailings with various hole diameters and GMB thicknesses. Finite element analyses are performed to explore the effect of hydraulic conductivities (k) of subgrade (underliner) and tailings above the GMB (overliner) on water head contours dissipation. An analytical solution is developed for predicting leakage through circular GMB hole overlain and underlain by both tailings. Results show that the effect of subgrade on leakage is highly dependent on the ratio of k between the underliner and the overliner. If the ratio >100, no head loss occurs in the subgrade; if the ratio <0.01, all the head loss occurs in the subgrade. With the deposition of fines from overliner into subgrade, a low permeable filter cake is formed on the subgrade surface, notably increasing the impact of underliner on leakage. With the increasing ratio of k between underliner and overliner from 0.01, 0.1, 1, 10, and to 100, the ratio of leakage relative to a highly permeable subgrade increases from 0.01, 0.1, 0.56, 0.93, and to 1. An intimate interface contact can be achieved when the GMB is underlain by silty sand tailings as subgrade (foundation) material.

Multi-ring side groups copolymer as an effective filtration control additive for water-based drilling fluids under high temperature and salt contamination

The control of filtration loss under high temperature and high salinity conditions has been a challenge in drilling fluid industry. In this study, a novel tetra-copolymer with multi-ring side groups was prepared with free radical polymerization as a filtration control additive. The copolymer consisting of N, N-dimethylacrylamide (DMAM) 2-acrylamide-2-methylpropanesulfonic acid (AMPS), N-acryloylmorpholine (ACMO), and sodium p-styrenesulfonate (SSS) was named DAAS. DAAS was analyzed for chemical structure and thermal stability, respectively. The rheological behavior and filtration performance of bentonite-based mud (BM) with DAAS addition was investigated under various temperatures and salt contamination (NaCl) conditions. The effect of DAAS on the dynamical stability of BM was analyzed by a multi-light scattering method. The relationship of DAAS absorption capacity on bentonite surface with concentration, absorption time, temperature and NaCl content was investigated in detail. The effect of DAAS on the chemical group, electrical properties, particle size of bentonite was studied to illuminate the mechanism. Based on the results, the DAAS maintained thermally stable up to 306 °C. DAAS enabled the BM to resist saturated salt contamination after aging at 200 °C with a filtration loss of 7.6 ml. DAAS with multiple ring groups absorbed on the bentonite by forming of hydrogen bond with bentonite. Even under saturated salt and high temperature conditions, the adsorption capacity of DAAS remained at a good level. The dispersion properties of BM were enhanced through decreasing the zeta potential and changing particle size of bentonite. One compact and low permeability filter cake was formed. The filtration loss of BM was finally controlled to a low volume.

Infiltration behaviour and microstructure of filter cake from sand-modified bentonite slurry

This study uses a setup involving a scanning electron microscopy (SEM) to examine the infiltration behaviour and mechanism of the formation of filter cake from sand-modified bentonite slurry. We began by determining whether a filter cake can be formed by using water–bentonite slurry in samples of the fine, medium, and coarse sand (Series 1). Water–bentonite–sand slurries with different mass ratios of bentonite and fine sand (B:S) were subsequently tested using the medium and coarse sand (Series 2). The results show that for Series 1, a thin filter cake (<0.1 mm after drying) with extremely low permeability (∼10−8 m/s) was formed only when the fine sand was used. The filter cake consisted of layers of dense bentonite platelets arranged perpendicular to the infiltration direction. Similar results were obtained for Series 2 between the medium and coarse sand. Within the range of 1:1.5 ≤ B:S ≤ 1:0.5, the low permeable filter cake was formed on the deposited layer of fine sand and bentonite platelet. Contrary to expectations, adding more sand (B:S = 1:2) did not complete the formation of filter cake, and instead led to continuous deposition of fine sand and bentonite platelet, which may cause inadequate effective face support during slurry shield tunneling.

Effects of seawater on the infiltration behavior of bentonite slurry into sand

As a support fluid, bentonite slurry has been extensively used in slurry shield tunneling to stabilize the tunnel face by forming a low-permeable filter cake. However, the infiltration behavior of bentonite slurry in complex conditions such as when suffering from seawater intrusion has not been fully understood. In order to investigate the infiltration behavior and filter cake formation under seawater intrusion, seawater-based bentonite slurries with increased salt content were prepared to represent different seawater intrusion severities. The rheological properties and physical stability of these slurries were evaluated. A series of infiltration column tests were conducted on two saturated sand beds with different particle sizes. Scanning electron microscope (SEM) was performed to unravel the microstructure of the filter cake. The infiltration column test results show that the low-permeable filter cake can be formed on the fine sand bed regardless of the salt content of the slurry. The salt shortened the time span of the mud spurt and made the filter cake more permeable to water. For the medium sand, the filter cake cannot be formed when the salt content exceeds 1%, because the deterioration of rheological properties of the slurry weakened its rheological blocking effect when infiltrating the sand. Based on the SEM images, it was found that the filter cake under seawater intrusion contained many well-connected inter-agglomerate channels that reduced its sealing quality. The obtained results can provide guidance and reference for the application of bentonite slurry when tunneling in a sea environment.

Zwitterionic Silica-Based Hybrid Nanoparticles for Filtration Control in Oil Drilling Conditions

Water-based drilling fluids (WBDFs) that are susceptible to high temperature and saline pollution always exhibit poor ability to control fluid loss and seriously threaten the operation security of oil well drilling; especially, ultradeep well WBDFs that can simultaneously tolerate high salinity and temperature of over 200 °C are difficult to obtain. Herein, a zwitterionic silica-based hybrid nanomaterial (ZSHNM) with a spherical morphology (50–150 nm) was synthesized, and its filtration performance was thoroughly investigated. ZSHNM showed an extraordinary long-term (≥10 months) dispersion stability even at high concentrations in water and possessed remarkable tolerance to high temperature and salinity. Typically, merely adding 2 wt % ZSHNM in WBDFs could achieve an excellent filtration performance even at 240 °C, and with 11 wt % CaCl2 or 36 wt % NaCl added, it showed the best performance to our knowledge. The results suggested that the sodium bentonite (Na-Bent) dispersion could be well stabilized in the presence of ZSHNM even at high temperature and with the presence of cations. Additionally, the silicate core could improve the thermal stability of ZSHNM, whereas the zwitterionic shell could form complexes with cations and further mitigate the aggregation of Na-Bent particles. Thus, the particle size distribution in WBDFs could be finely regulated similar to that in neat Na-Bent dispersion. Furthermore, given the zwitterionic ZSHNM filled in the micro–nanopores among the Na-Bent particles, a compact and low-permeability filter cake was readily formed and ultimately reduced the drilling fluid loss during the filtration process. This work provided a versatile strategy to address the high temperature and high salinity tolerance of WBDFs synchronously, thereby pioneering a new way to develop high-performance drilling additives for ultradeep and complex wells.

Application of Cellulosic Fibrous Material from Agro Waste as Filtrate Loss Modifier in Aqueous Mud-Morphology at HTHP Conditions

Controlling the filtration characteristics of any drilling fluid does not only include the control of the filtrate volume penetrating into the formation; but also the ability of the mud to deposit a thin low-permeability filter cake on the wall of the wellbore quickly. The permeability of the filter cake is very dependent on the particle size because when small size particles are used, the permeability decreases, because of the fact that colloidal particles get packed very tightly. This study investigated the filtration and filter cake characteristics of water-based mud (WBM) using fibrous cellulose from Tiger Nut waste and the guar gum. American Petroleum Institute (API) Recommended Practice Standard Procedure for Field Testing Drilling Fluids, API RP 13B-1 was applied during the analysis. Statistical analysis of the experimental data was conducted and the R2 value (0.99) showed that the experimental method adopted was replicable. Mud samples B2 and C2 gave an optimum result and their mud cakes developed under High-Temperature High-Pressure (HTHP) condition were dried and further analyzed with scanning electron microscope (SEM). The results showed that the filter cakes SEM structure for cellulosic fibrous from agro waste and guar gum exhibits similar characteristics; and the mud cakes was firm after soaking with 15% HCl for thirty minutes but started dissolving after one hour. The SEM analysis inferred that the filter cake morphology shows a good particle-pore interlocking for sample C2 than B2.

Effects of slurry viscosity and particle additive size on filter cake formation in highly permeable sand

Filter cake is critical to maintaining the stability of the excavation face of an underwater shield tunnel in a high-permeability stratum. In a high-permeability formation, generating an effective filter cake on the excavation face is difficult with a pure bentonite slurry, which penetrates the ground and may not achieve the required suspension pressure. Determining how to efficiently and quickly form a thin and low-permeability filter cake on the tunnel working face has become a key engineering problem in the construction of slurry shield tunnels in high-permeability strata. In this study, the relationship between slurry viscosity and the slurry pressure gradient of pure bentonite was established by performing slurry permeability experiments. The influence of slurry viscosity on the formation of the filter cake in a high-permeability formation was studied under different pressure gradients. In addition, the effect of additive particle size on the slurry filter cake formation was analyzed by introducing additives with different particle sizes to pure bentonite slurries with different viscosities. The test results indicate that (1) for the pure bentonite slurry, the critical initial pressure gradient can be used as a rough indicator of the formation of the filter cake, and the relationship between the critical maximum pore diameter and the average pore diameter of the formation can be compared to establish and analyze the formation law of the slurry filter cake; (2) adding particles to the slurry can enhance the effect of the pure bentonite slurry; and (3) adding coarse-grained materials can effectively improve the film-forming effect. The slurry is more compact when the particle size is close to the average pore size of the formation.

Результаты исследования влияния жидкостей-разрушителей на полимерминеральную фильтрационную корку

In the course of well construction, deterioration of the natural reservoir properties of the formation is inevitable. A dense lowpermeability filter cake formed on the surface of the bottomhole formation zone at the stage of completion contributes to a decrease in the reservoir properties of the rock, and hence the productivity of the well. In addition, the cake can contribute to the plugging of structural elements such as the well screen or inflow control devices, thereby also having a negative impact on the flow rate. In most cases, the impossibility of achieving the required cleaning of the bottomhole zone during well completion in the future leads to the need to use expensive repeated operations and overhaul, chemical and mechanical methods of cleaning the bottomhole formation zone. The development of technologies for the complete removal of the formed filter cake from the borehole walls is a necessary task. The paper considers the water-based biopolymer solution of the primary opening of the productive formation, the component composition and its parameters are given. A method is described for studying the effect of breaker systems on a polymer-mineral filter cake under high-pressure conditions using filter press HT-HP, and a method for determining the dissolving capacity of individual components of the system (chelate and enzyme). Based on the results of this study, the optimal composition of the breaker of the enzyme-chelate base was selected, after the action of which the most complete destruction of the crust constituents was observed. The results were evaluated by comparing the dissolving power of calcium carbonate when exposed to different chelates. The enzyme alpha-amylase was used as a starch breaker. The efficiency of the composition was confirmed by the change in the filtration-capacitive properties of ceramic discs before and after processing in comparison with foreign analogues of breaker systems.

Performance of carbonate calcium nanoparticles as filtration loss control agent of water-based drilling fluid

Application of nanoparticles in improvement of drilling fluid properties through effective control of fluid loss and rapid formation of thin, smooth and low permeable filter cake has gained considerable attention in recent years. In this study, calcium carbonate nanoparticle was synthesized by precipitation method and characterized by X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscope (SEM), dynamic light scattering and Zeta-potential measurement. Water based bentonite drilling fluid was used as base fluid. Various concentrations of calcium carbonate nanoparticle (0.025–0.5 wt%) was added to water-based drilling fluid. Fluid loss volume, filter cake thickness and its surface morphology, and rheological properties of both base fluid and fluid containing calcium carbonate nanoparticles was measured and compared. Results show that addition of calcium carbonate nanoparticle greatly affects filtration properties and forms smoother cake surface. Optimum concentration of 0.07 wt% calcium carbonate nanoparticle was obtained which results in reduction of fluid loss volume and filter cake thickness by 26% and 64% respectively while minor change in rheological behavior was observed. SEM image showed smoother cake surface of drilling fluid with calcium carbonate nanoparticle as additive compared to base drilling fluid. Considerable improvement in filtration properties using acid soluble CaCO3 nanoparticles can help in minimizing fluid leak-off and formation damage of producing layers and more effective well cleanup for fast oil and gas production.

Comparison of the behaviour of various geotextiles used in the filtration of clayey sludge: An experimental study

This paper presents the results of an experimental study of various geotextiles used to filter clayey sludge. The use of geotextiles to filter clayey sludge or suspensions of fine particles in water is more complex than that for filtering suspensions of granular soils. In practice, such applications generally use flocculants to postpone the formation of a low-permeability filter cake. The objective of the present study, which does not use flocculants, is to determine how geotextile characteristics affect the capacity of the geotextile to filter clayey sludge. Three key questions are addressed: (1) What are the main differences between vertical and horizontal filtration? (2) How do geotextile characteristics (nature, opening size, permeability, etc.) affect its capacity to filter clayey sludge (3) How do clayey sludge characteristics (i.e., grain size distribution and concentration)? and the type of flow (i.e., constant head or constant flow) affect the filtering capacity of geotextiles? To evaluate the capacity of a geotextile to filter clayey sludge, we propose three relevant criteria and analyse two filtration phases induced by different cake-formation processes (controlled by the geotextile and controlled by the filter cake). To determine the main differences between vertical and horizontal filtration, the settling of fines in the testing device and its influence on the results are analysed and discussed. This study shows that, for the various clayey sludge tested, the geotextiles (needle-punched nonwoven and thermally bonded nonwoven) with the smallest opening sizes (O90 ≤ 60 μm) give the most promising results for filtering fines without the use of flocculants. Of these geotextiles, the thermally bonded nonwoven structure seems to offer the best filtration performance for the largest range of fines concentration in the sludge.

An approach to improve the cuttings carrying capacity of nanosilica based muds

Rheological and filtration properties of water based muds play vital roles to have a good drilling efficiency in high pressure high temperature (HPHT) environments. However, there are many occasions where controlling the variation of mud properties due to disintegration of additives is barely possible, resulting in stuck pipe, kick incident or even loss of wells. Although there have been many studies in the past indicating the application of nanosilica in improving the flirtation control of water base muds, there are almost no studies on the significant reduction of the yield point which may cause a huge decrease in cutting carrying capacity of muds and rate of penetrations. The aim of this study is to propose an approach to improve the filtration control of water based muds using nanosilica while maintaining the rheology by using a cationic surfactant.The results obtained from zeta potential measurements indicated that bentonite and nanosilica particles are both negatively charged at different ranges of pH, which would result in reduction of the yield point of the mud samples containing nanosilica. This issue was resolved by employing a cationic surfactant and following certain procedures. Filtration tests conducted under LPLT and HPHT conditions indicated that adding modified nanosilica into the mud samples creates a thin and low permeability filter cake without having any negative impacts on the rheology.

The Research on Smart Drill-In Fluid Design

There are continuous high concerns on formation protection technology in international petroleum engineering field. The reservoir drill-in fluid (RDF) is the first non-native fluid to contact formation, and which influences directly the ultimate capacity of oil and gas well. The paper discusses the smart RDF design method based on conventional drilling fluid. The designed RDF system is characterized as good formation damage control, as well as the performance easily adjusted for field application. The technology combines ideal packing technology with active calcium carbonate to obtain low permeability filter cake, high return permeability and low initial flowing pressure. The sized calcium carbonates contribute to develop sealing zone for preventing filtrate and solids from invading into formation, and the organophilic passageway in filter cake (the active calcium carbonate) is favorable to open automatically passageway for oil and gas during production. Different modifiers used to ground calciumcarbonate surface modification are evaluated in laboratory. And the laboratory results show modified calcium carbonates are comfortable with conventional drilling fluids additives such as XC(Xanthan ), potassium polyacrylate(K-PAM), sodium carboxymethyl cellulose(Na-CMC).

Characterization of Commercial Amylases for the Removal of Filter Cake on Petroleum Wells

Drilling fluid has many functions, such as carry cuttings from the hole permitting their separation at the surface, cool and clean the bit, reduce friction between the drill pipe and wellbore, maintain the stability of the wellbore, and prevent the inflow of fluids from the wellbore and form a thin, low-permeable filter cake. Filter cake removal is an important step concerning both production and injection in wells, mainly concerning horizontal completion. The drilling fluids are typically comprised of starch, the most important component of the filter cake. A common approach to remove this filter cake is the use of acid solutions. However, these are non-specific reactants. A possible alternative is the use of enzymatic preparations, like amylases, that are able to hydrolyze starch. Wells usually operate in drastic conditions for enzymatic preparations, such as high temperature, high salt concentration, and high pressure. Thus, the main objective of this work was to characterize four enzymatic preparations for filter cake removal under open hole conditions. The results showed that high salt concentrations (204,000 ppm NaCl) in completion fluid decreased amylolytic activity. All enzymatic preparations were able to catalyze starch hydrolysis at all temperatures tested (30, 65, 80, and 95 degrees C). An increase of amylolytic activity was observed with the increase of pressure (100, 500 and 1,000 psi) for one commercial amylase.

The Use of Filtration Theory in Developing a Mechanism for Filter-Cake Deposition by Drilling Fluids in Laminar Flow

Summary This paper presents a mechanism for filter-cake deposition by drilling fluids in laminar flow. The mechanism evolved from analysis of filtration-data plots obtained from two linear equations derived from filtration theory. With these plots, various fluid-loss additives were evaluated on their ability to form a low-permeability filter cake that can be eroded by a fluid in laminar flow. The mechanism was tested on two wells with high torque and drag, and the static API high-temperature/high-pressure (HTHP) values were minimized.