Neutral Wetting Research Articles

On the lifetimes of two-dimensional droplets on smooth wetting patterns

We study the evolution and lifetime of droplets evaporating on a smooth chemical pattern, which is characterised by a spatially varying contact angle. We formulate a model that combines the evaporation rate of the droplet for a given volume with the static stability of the droplet as the volume changes in time quasi-statically. We derive an exact equation for the evaporation rate that is studied analytically under the limiting cases of nearly neutral wetting and highly hydrophilic conditions. We find that the evaporation rate of the droplet is highly dependent on the size and shape of the fictitious infinity where a far-field boundary conditions needs to be applied. We also study how the droplet’s lifetime depends on the averaged contact angle and strength varepsilon of the chemical pattern, observing that the lifetime of the droplet is maximised for a droplet with average contact angle pi /2 and with varepsilon lesssim 0.1.

Rock Wettability Characteristics Of Some Indonesian Limestones Case Study: Baturaja Formation

Rock wettability plays a very important role in affecting various rock physical properties such as relative permeability and capillary pressure. Common practice at present is that carbonate rocks are assumed to be preferentially oil wet in nature. This assumption may prove fatal since the need of true knowledge over the real wettability for one’s carbonate reservoir is often neglected, and wettability aspect in reservoir modeling is in turn based on assumption. To prove over reliability of the assumption a study is carried out using information from 350 core samples taken from Baturaja Formation. The choice for the Baturaja limestone is basically based on the fact that it is a mature productive rock formation and its extensive spread into three of the most productive sedimentary basin in Indonesia, Northwest Java Basin, South Sumatra Basin, and Sunda Basin. The study proves that the assumption of the generally oil wet limestone does not apply for Baturaja limestone. The Baturaja limestone tend to exhibit, quantitatively, equality in their tendency towards oil wettability and water wettability and leave some proportion to neutral or mix wettability as well. However, when a more detailed comparison is made results show that qualitatively the limestone are indeed more inclined to oil wettability than water wettability even though this finding is insufficient to support a conclusion that the Baturaja limestone are specifically oil wet. Other finding from comparison with past studies also shows that limestone may behave in the way sandstones do. Both limestone and sandstones may vary in the same way and no assumption over their preferential wettability is justified without direct measurements. Wettability alteration as the result of hot core cleaning following the widely accepted standard procedure is also strongly indicated. It is therefore concluded that the practice has to be abandoned for a better and reliable laboratory testing results.

An Investigation Over Rock Wettability And Its Alteration On Some Indonesian Sandstones

Wettability is a reservoir rock property that is not easy to measure and quantify but has a crucial effect on other rock properties such as relative permeability, capillary pressure, and electrical properties. Problem that may occur with regard to this matter is that those properties are often measured on already cleansed core samples as part of the standard procedure. Having undergone the normally utilized heated cleansing process alteration in the rock’s original wettability was often reported. Under such condition, unrepresentative wettability certainly leads to unrepresentative measured data with all of consequences. This article presents a study that uses 363 sandstone samples retrieved from 28 oil and gas fields in Indonesia. The study consists of two stages of analysis. First analysis is performed on data obtained from three wettability tests results while the second one is made with using water-oil relative permeability data, that is usually measured on cleansed core samples. Original wettability data shows that the sandstones varry in wettability from water-wet to oil-wet (48.2% and 30.2% of total samples, respectively). Comparison between data of the two analyses shows that original wettability tends to degrade in strength after cleaning down to neutral wettability, among which neutral wettability appears to be the largest in number (49.1% of total sample). Results also show that weak wettability tends to endure more than stronger ones. The overall results have demonstrated the need for caution in core handling and for measures that can minimize the risk.

Numerical analysis of the pore-scale mechanisms controlling the efficiency of immiscible displacement of a pollutant phase by a shear-thinning fluid

Knowledge of the pore-scale physics of underground multiphase flows is essential to devise efficient soil remediation methods. However, the immiscible displacement of pollutant through the injection of a shear-thinning fluid remains poorly understood. The current work presents a full set of direct numerical simulations in which a Newtonian contaminant is displaced by a Carreau fluid or, alternatively, by a Newtonian fluid, in three porous media with different degrees of microstructural complexity. Imbibition, drainage and neutral wettability cases are considered, and the sensitivity of residual pollutant saturation to Carreau’s law parameters is also assessed. The present results allow for the quantification of the performance of immiscible displacement using shear-thinning invading fluids. This performance is shown to depend on the value of capillary number and the heterogeneity of the porous microstructure, which determine the relative importance of viscous fingering, capillary forces and pollutant trapping behind the invasion front.

Utilizing protein-polyphenol molecular interactions to prepare moringa seed residue protein/tannic acid Pickering stabilizers

The formation of complexes between plant proteins and polyphenols is being explored for the development for functional ingredients with new or improved properties. In this study, complexes were fabricated from moringa seed residue protein (MSRP) and tannic acid (TA). Fourier transform infrared spectroscopy and isothermal titration calorimetry suggested that the main interactions between MSRP and TA were hydrophobic and hydrogen bonding. The MSRP-TA complexes had near neutral wettability (θow = 86.1°), which meant that they could adsorb strongly to oil-water interfaces and thereby form and stabilize Pickering emulsions. The stability of the emulsions was improved by optimizing the MSRP:TA ratio. Confocal laser scanning microscopy indicated that higher tannic acid concentrations enhanced the thickness and compactness of the MSRP-TA interfacial layers formed around the oil droplets. The physicochemical properties of the emulsions were measured over a range of pH (3–9) and ionic strength (0–0.4 M NaCl) conditions. These results showed that the complexes were able to form stable emulsions at lower ionic strengths (<0.2 M) and higher pH values (pH 7–9). Overall, this study shows that self-assembly of MSRP and TA can improve the emulsifying properties of MSRP, which may increase its application as an emulsifier in foods.

Impact of Wettability and Gravity on Fluid Displacement and Trapping in Representative 2D Micromodels of Porous Media (2D Sand Analogs)

AbstractThe combined effects of gravitational forces and wettability on displacement and trapping have not previously been investigated experimentally in realistic 2D porous media. Here we report the first use of representative 2D micromodels that accurately reproduce characteristic geometric, morphological, and topological properties of 3D sand packs. We use these representative micromodels to compare the wettability dependence of displacement front morphology and trapping processes using selected fluid pairs at capillary numbers between 10−6 and 10−5. The contact angles studied ranged from 30° (normal imbibition) to 150° (strong drainage). The impact of gravity was dramatic: In the horizontal flow case, only one finger developed, that is longitudinal displacement was always favored, whereas gravity created a more compact displacement front with broad lateral extension, and this lateral movement created loops, leading to by‐pass trapping. As a result, the trapping efficiency rose from 7% to 29%. We observed universal scaling of the cluster size distribution demonstrating that our micromodels are statistically representative. The universal 2D‐scaling exponent of 2.05 was obtained with an acceptable error smaller than 5%. Our experimental results obtained by fluorescence microscopy showed (a) precursor corner flow for weak imbibition at θ = 51°, that is above the critical contact angle of αc = 45° (Zhao et al., 2016, https://doi.org/10.1073/pnas.1603387113), and (b) a new wetting transition from corner flow to full duct flow under neutral wettability conditions, that is at θc ≈ 90°; and (c) above this second critical contact angle, that is under strong drainage conditions, we again observed corner flow (specifically, core‐annular flow).

Wettability alteration using functionalized nanoparticles with tailored adhesion to the rock surface for condensate banking mitigation

AbstractAccumulation of liquids near the wellbore in gas reservoirs can result in what is known as liquid banking, causing loss of gas and liquid production. One of the techniques that can be used to mitigate liquid banking is changing the rock wettability from liquid wetting to neutral wetting, allowing the gas to carry the liquid out of the pore space. Double‐functionalized wettability altering silica (SiO2) nanoparticles (NPs) were developed. The synthesized NPs were functionalized with both fluoro‐silane (F‐SiO2 NPs) and a charged functional group to enable coupling of the NPs to the substrate. Surfaces treated with F‐SiO2 NPs functionalized with coupling functional group showed superior wear and corrosion resistance in high salinity water compared to single‐functionalized F‐SiO2 NPs. By functionalizing 125 nm SiO2 NPs first with polyethylenimine (PEI‐) or N‐(2‐Aminoethyl)‐3‐aminopropyltrimethoxysilane (DAMO‐) l group followed by fluorination, a water contact angle of 120°and decane contact angle of 70° was achieved. Core flow testing performed under realistic reservoir conditions of pressure and temperature showed that F‐SiO2 NPs coated with PEI achieved a 58% improvement in gas and liquid relative permeability, indicating improvement in the surface repellency to liquids and reduction of the trapped liquid phases inside the pore space of the rocks. The developed double‐functionalized NPs achieved similar performance to the commercially used fluorinated surfactants but using less treatment volume. In addition, these double‐functionalized NPs enable one‐step treatment in the field, which results in simpler operations, shorter treatment time, and better treatment economics.

Influence of wettability and initial size on the merging dynamics of droplet within a Y-shaped bifurcating channel

Present study numerically investigates the merging dynamics of two identical dispersed droplets within a Y-shaped bifurcating channel of rectangular cross-section. A finite element method based solver is adopted to analyze the flow dynamics within the bifurcating channel for different wall wettability conditions, initial size of the dispersed droplets and for a fixed Capillary number. The merging dynamics is described with the help of morpho-dynamic evolution along with the temporal evolution of wetted area of the droplets. It reveals that the daughter droplet generated from the mating of identical parent droplets at the bifurcating tip has the affinity to stick at the junction for hydrophilic and neutral wettability configurations of the walls, thus generating longer size droplet. On the contrary, for hydrophobic wettability of the walls, the parent droplets merge to each other bypassing the bifurcating junction while mating and subsequently entrapping of droplets takes place within the daughter droplet. Moreover, the influence of wall wettability is insignificant when the initial sizes of the parent droplets are smaller.

Fabrication and characterization of Pickering emulsion gels stabilized by zein/pullulan complex colloidal particles.

Zein particles are unsuitable as stabilizers of Pickering emulsions because of their high hydrophobicity. However, few studies have reported on the use of a strong hydrophilic neutral polysaccharide to regulate its wettability. In this work, zein/pullulan complex particles (ZPPs) were formulated by an anti-solvent method to fabricate Pickering emulsions. The presence of pullulan increased the size, decreased the zeta, and provided excellent resistance to the gravitational separation of zein. Scanning electron microscopy (SEM) revealed that the shape of zein particles changed from spherical as they became aggregated ZPP nanoparticles. Fourier transform infrared (FTIR) spectroscopy indicated that the flocculation phenomenon of ZPPs was related to the hydrogen bond between zein and pullulan. Moreover, the hydrophobicity of zein was modified by hydrophilic pullulan to endow the ZPPs with nearly neutral wettability when the mass ratio was 15:1, allowing for the preparation of stable Pickering emulsions. In contrast to zein, the ZPPs contributed to building a compact interface layer around the droplets and smaller emulsion droplets. Under a certain ZPP concentration, the size and viscosity of emulsion increased with an increase in the oil volume fraction, indicating that the Pickering emulsions stabilized by ZPPs showed better stability against coalescence. Confocal laser scanning microscopy (CLSM) revealed that the ZPPs constructed a dense filling layer on the surface of oil droplets, thus further emphasizing that ZPPs can potentially be used in fabricating Pickering emulsion gels. Zein/pullulan complex particles are an excellent Pickering emulsion gel stabilizer that can be used in the delivery system of bioactive substances in food formulations. © 2020 Society of Chemical Industry.

Experimental Investigation on a Novel Polyelectrolyte Molecular Deposition Film for Improved Injectivity in Low-Permeability Reservoirs.

Acrylamide and dimethyl diallyl ammonium chloride were used as monomers to synthesize a polyelectrolyte molecular deposition film (PMDF) injection agent for solving the problem of high injection pressure of water wells in low-permeability reservoirs. The structure of the PMDF injection agent was determined through IR and 1H nuclear magnetic resonance (NMR). The performance evaluation results show a change of wettability from hydrophilic to neutral wetting with the contact angle changing from 22.32 to 73.31° because of agent injection. It can also change the negative ζ-potential on the surface of the sand to a positive value. For comparison, core displacement experiments involving the commercial Gemini surfactant DF-G reveal that the effects of the depressurization of PMDF are more obvious than those of DF-G. The adsorption stability of the former is better than that of the latter. Especially, under a high-speed water flow of 30 pore volume (PV) injection, the depressurization rate of PMDF is still as high as 43.59%. Finally, the oil–water relative permeability curves and core nuclear magnetic resonance (NMR) experiments demonstrate that the PMDF treatment can reduce the irreducible water saturation, which indicated that the porosity of the flowable part of the core increased and the swept volume was increased. The suitable range of PMDF according to NMR pore-radius distribution within a low-permeability reservoir: the flowable partial pore required the throat radius greater than 0.01 μm.

Particle size and substrate wettability dependent patterns in dried pendant drops

The particle laden sessile drops when dried on solid surfaces under certain conditions leave a deposit pattern wherein all the particles are confined to a narrow region close to the edge of the deposit. Such patterns which often form when coffee drops dry are referred to as the coffee ring patterns or the coffee stains. Recent research points to the formation of intriguing patterns when colloidal particle laden drops are dried in configurations other than sessile mode. In this article, the combined effect of particle size and wettability of the substrate on the patterns formed by drying drops in sessile and pendant configurations is investigated via experiments. Our results demonstrate a transition from coffee ring to central dome-like deposit morphology with decrease in wettability of the substrates when drops containing 3 μm diameter particles are dried in pendent mode. A similar transition in the deposit morphology is observed with increase in the diameter of the particles in pendant drops dried on substrates of near neutral wettability (θ = 86 ± 3°). The influence of particles size, substrate wettability and drop configuration on the kinetics of deposition of particles at the three phase contact line will also be discussed. We compare our experimental observations with particle based simulations wherein the dried patterns are generated by accounting for three particle transport modes, namely, advective particle transport resulting from capillary flow, gravity driven settling of particles and particle capture by descending interface.

Universal Interfacial Control through Polymeric Nanomosaic Coating for Block Copolymer Nanopatterning.

The employment of self-assembly of soft materials has been accepted as an inexpensive, robust, and reliable patterning method. As their self-assembly relies on the delicate molecular interactions near the substrate, a precise prediction/control of the interface structure and dynamics is critical to achieve desired nanostructures. Herein, a polymeric nanomosaic (PNM) pattern is created from the air/water interfacial self-assembly of a block copolymer (BCP) and introduced as an effective interfacial energy control for substrates. As a demonstration, the PNM coating is employed to control the BCP film structures. The perpendicular orientation of BCP self-assembly, which requires neutral wetting conditions for both blocks, is difficult to achieve but can readily be obtained with the PNM coating upon a fine resolution of the pattern quality. The universal applicability of the PNM coating as an interfacial control has been confirmed on curved, flexible, and three-dimensional substrates. In addition, the PNM is introduced as an etching-free and reusable topcoat imparting free surface neutralization even for the high-χ BCP nanopatterning.

Brine composition effect on the oil recovery in carbonate oil reservoirs: A comprehensive experimental and CFD simulation study

In order to understand the potential role of divalent ions involved in smart water, fluid-fluid and rock-fluid interactions are studied through contact angle and interfacial tension (IFT) measurements. Then, the suitable brines in changing contact angle and IFT are brought into measurement with spontaneous imbibition experiments to evaluate the co-impact of fluid-fluid and rock-fluid interactions. The results show the importance of SO42− ions during smart water injection as removing them from the injection water leads to a sharp drop in ultimate oil recovery. Accordingly, when the concentration of SO42− within the injection water increases four times, 10% ultimate oil recovery is recovered. Furthermore, the spontaneous imbibition measurements exhibit the higher ultimate oil recovery from the neutrally-wet core plugs more rather than the strong water-wet plugs. Further elaborating about the effect of wettability on the pore-scale displacement of oil by injection water is conducted through Computational Fluid Dynamics (CFD) modelling. The results confirm that the lowest residual oil saturation is achieved in the model with neutral wettability state as well as the highest oil recovery which is in line with the piston-like displacement in the neutral wet rock medium.

Rapeseed Protein Nanogels As Novel Pickering Stabilizers for Oil-in-Water Emulsions.

Recently plant protein Pickering particles have received tremendous interests because of their environmentally friendly, biodegradable, and safe characteristics. However, developing plant protein particles as stabilizers of Pickering emulsion still face many challenges. In current study, a novel nanogel system produced from acylated rapeseed protein isolates (ARPI) was used to stabilize Pickering emulsions. Results showed that self-assembled nanogel after native RPI modified by acylation adjusted the three-phase contact angle of ARPI nanogels system to 86.7° closing to a neutral wettability. At constant oil phase fraction (0.3, v/v), increasing the ARPI nanogels concentrations produced smaller droplet sizes of Pickering emulsions, whereas all freshly prepared Pickering emulsions were stable except 0.1% (w/v) ARPI nanogel-stabilized Pickering emulsion occurred with creaming. The rise of the oil phase fraction showed little influences on the droplets size and visual appearances of Pickering emulsions at a fixed ARPI nanogels concentration (0.75%, w/v). Moreover, the prepared ARPI nanogels stabilized Pickering emulsions were stable against aggregations of droplets at a range of pH conditions ranging from 5.5 to 8.5 and salt concentration as high as 0.2 M. Additionally, the ARPI nanogels concentration above 0.5% favored the formation of Pickering emulsion with long-term storage stability (up to 30 days) against creaming. Microscopic images evidenced that ARPI nanogels could absorb and anchor at the droplets surface forming an interfacial layer. Above findings may deliver a potential strategy for fabricating stable Pickering emulsion based on plant protein particles and are of important significance for the utilization of rapeseed protein in the food industry.

Experimental and modeling study of wettability alteration through seawater injection in limestone: a case study

Water flooding is widely applied for pressure maintenance or increasing the oil recovery of reservoirs. The heterogeneity and wettability of formation rocks strongly affect the oil recovery efficiency in carbonate reservoirs. During seawater injection in carbonate formations, the interactions between potential seawater ions and the carbonate rock at a high temperature can alter the wettability to a more water-wet condition. This paper studies the wettability of one of the Iranian carbonate reservoirs which has been under Persian Gulf seawater injection for more than 10 years. The wettability of the rock is determined by indirect contact angle measurement using Rise in Core technique. Further, the characterization of the rock surface is evaluated by molecular kinetic theory (MKT) modeling. The data obtained from experiments show that rocks are undergoing neutral wetting after the aging process. While the wettability of low permeable samples changes to be slightly water-wet, the wettability of the samples with higher permeability remains unchanged after soaking in seawater. Experimental data and MKT analysis indicate that wettability alteration of these carbonate rocks through prolonged seawater injection might be insignificant.

Microscopic mechanism of water flooding in tight reservoirs

Based on cores from tight oil reservoirs in Ordos Basin, water flooding experiments with both low and high displacement pressures were carried out. Combined with NMR, quantitative analysis approaches for produced oil under different microscopic effects were established for quantitative research of the microscopic mechanism of water flooding in tight reservoirs. The research indicated that under low displacement pressure, oil recovery mechanisms of hydrophilic cores mainly include displacement, imbibition, and denudation, and those of wetting cores mainly include displacement and imbibition. After increasing the displacement pressure, both hydrophilic and neutral wetting cores have a certain increase in oil recovery. The common point is that both oil controlled by small throats and remaining oil droplets controlled by traps in large pores have been activated, while the discrepancy is that the oil film of the neutral wetting core boundary layer becomes thinner, which improves oil recovery ratio, and these mechanisms have less effect on hydrophilic cores. The amount of oil produced by each type of oil recovery mode was quantitatively analyzed. Percentages of produced oil in hydrophilic cores by flooding and imbibition and denudation are 15% and 12%, respectively, which are the main oil recovery mechanisms; percentages of produced oil in neutral wetting cores by displacement and imbibition are 25% and 2%, respectively, with displacement as the main oil recovery mechanism. After increasing the displacement pressure, oil produced by hydrophilic and neutral wetting cores increased by 6% and 9%, respectively, indicating that with increasing the displacement pressure, a part of the boundary layer of oil could be produced in neutral wetting cores.

Discrete fluidization of dense monodisperse emulsions in neutral wetting microchannels.

The rheology of pressure-driven flows of two-dimensional dense monodisperse emulsions in neutral wetting microchannels is investigated by means of mesoscopic lattice Boltzmann simulations, capable of handling large collections of droplets, in the order of several hundreds. The simulations reveal that the fluidization of the emulsion proceeds through a sequence of discrete steps, characterized by yielding events whereby layers of droplets start rolling over each other, thus leading to sudden drops of the relative effective viscosity. It is shown that such discrete fluidization is robust against loss of confinement, namely it persists also in the regime of small ratios of the droplet diameter over the microchannel width. We also develop a simple phenomenological model which predicts a linear relation between the relative effective viscosity of the emulsion and the product of the confinement parameter (global size of the device over droplet radius) and the viscosity ratio between the disperse and continuous phases. The model shows excellent agreement with the numerical simulations. The present work offers new insights to enable the design of microfluidic scaffolds for tissue engineering applications and paves the way to detailed rheological studies of soft-glassy materials in complex geometries.

Pore-scale numerical modeling of coupled fluid flow and medium geometrical deformations in an unconsolidated porous medium

The interplay of fluid flow and medium grains' deformation/movement in unconsolidated porous media was numerically studied. The numerical simulations were done through coupling Cahn-Hilliard phase field and Navier-Stokes equations for fluid flow as well as stress-strain and Arbitrary Lagrangian/Eulerian mesh alteration equations for geomechanical effects, by the finite-element method. Single/two-phase flow through a real patterned micro-scale medium with/without grains' deformation and movements/rotation were studied. In single-phase models, the fluid velocity distribution was quite similar for the cases with rigid grains and that with only deformed grains. However, in an unconsolidated medium, the velocity magnitude and distribution were modified. The medium porosity had a linear trend with pressure, and was independent of the grains' movement/rotation. The models with deformed grains showed good agreement with Kozeny-Carman equation in permeability variation versus pressure. In the two-phase flow models, the velocity/displacement profiles, relative permeability end-points and capillary pressure were quantitatively compared in rigid and unconsolidated media versus medium wettability. The effect of the grains' deformation on the fluid distributions was negligible at low capillary numbers, especially in water-wet and neutral wetting conditions. However, the grains' movement/rotation considerably modified the flow regime at different grains' contact angles. At higher capillary numbers, the grains' deformation effect was more pronounced.

Enhancing the spontaneous imbibition rate of water in oil-wet dolomite rocks through boosting a wettability alteration process using carbonated smart brines

Most fractured carbonate oil reservoirs have oil-wet rocks. Therefore, the process of imbibing water from the fractures into the matrix is usually poor or basically does not exist due to negative capillary pressure. To achieve appropriate ultimate oil recovery in these reservoirs, a water-based enhanced oil recovery method must be capable of altering the wettability of matrix blocks. Previous studies showed that carbonated water can alter wettability of carbonate oil-wet rocks toward less oil-wet or neutral wettability conditions, but the degree of modification is not high enough to allow water to imbibe spontaneously into the matrix blocks at an effective rate. In this study, we manipulated carbonated brine chemistry to enhance its wettability alteration features and hence to improve water imbibition rate and ultimate oil recovery upon spontaneous imbibition in dolomite rocks. First, the contact angle and interfacial tension (IFT) of brine/crude oil systems were measured for several synthetic brine samples with different compositions. Thereafter, two solutions with a significant difference in WAI (wettability alteration index) but approximately equal brine/oil IFT were chosen for spontaneous imbibition experiments. In the next step, spontaneous imbibition experiments at ambient and high pressures were conducted to evaluate the ability of carbonated smart water in enhancing the spontaneous imbibition rate and ultimate oil recovery in dolomite rocks. Experimental results showed that an appropriate adjustment of the imbibition brine (i.e., carbonated smart water) chemistry improves imbibition rate of carbonated water in oil-wet dolomite rocks as well as the ultimate oil recovery.

Design and Evaluation of a Surfactant–Mixed Metal Hydroxide-Based Drilling Fluid for Maintaining Wellbore Stability in Coal Measure Strata

Co-exploitation of coal measure gases (coalbed gas, shale gas, and tight sandstone gas) puts a higher requirement on drilling fluids. Conventional drilling fluids have disadvantages, such as causing problems of borehole collapse, formation damage, and water blockage. This paper proposes a set of high inhibitive and low-damage drilling fluids that function by electrical inhibition and neutral wetting. Zeta potential results showed that the negative electrical property of Longtan coal in Bijie, Guizhou, can be reversed by organic mixed metal hydroxide (MMH) and the cationic surfactant alkyl trimethylammonium bromide (CS-5) from −3.63 mV to 19.75 mV and 47.25 mV, respectively. Based on the contact angle and Fourier Transform Infrared Spectroscopy (FT-IR) results, it can be concluded that chemical adsorption dominates between the Longmaxi shale and surfactants, and physical adsorption between the Longtan coal and surfactants. A compound surfactant formula (0.001 wt% CS-4 + 0.001 wt% CS-1 + 0.001 wt% CS-3), which could balance the wettability of the Longmaxi shale and the Longtan coal, making them both appear weakly hydrophilic simultaneously, was optimized. After being treated by the compound surfactants, the contact angles of the Longmaxi shale and the Longtan coal were 89° and 86°, respectively. Pressure transmission tests showed that the optimized combination of compound surfactants and inorganic MMH (MMH-1) could effectively reduce permeability of the Longmaxi shale and the Longtan coal, thus retarding pore pressure transmission in coal measure strata. Then, the proposed water-based drilling fluid (WBDF) system (4 wt% sodium bentonite + 1.5 wt% sodium carboxymethyl cellulose + 2 wt% lignite resin + 5 wt% potassium chloride + 3 wt%MMH-1 + 0.001 wt% CS-4 + 0.001 wt% CS-1 + 0.001 wt% CS-3) was evaluated based on parameters including rheology, American Petroleum Institute (API) filtration, electrical property, wettability, inhibition capability, reservoir protection characteristics, and anti-pollution performance. It had an API filtration of 7 mL, reservoir damage rate of 10%, moderate and acceptable viscosity, strong inhibition capability to coal measure strata rocks, good tolerance to inorganic pollutants and drilling cuttings, and environmentally friendly properties. It could meet wellbore stability and reservoir protection requirements in the co-exploitation of coal measure gases.