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A fundamental chemical enhanced oil recovery (EOR) process is surfactant flooding in which the key mechanism is to reduce interfacial tension between oil and the displacing fluid and hence mobilizing the trapped oil. Surfactant loss by adsorption is one of the most important criteria that governs the economics of the surfactant flooding methods. In addition to this, detrimental effects and high price of currently used surfactants cause EOR process so expensive and unfeasible. This study is aimed to introduce a novel kind of plant based surfactant which is extracted from Zizyphus Spina-Christi tree. In addition, equilibrium adsorption behavior of this novel biosurfactant in aqueous solution on crushed reservoir rocks is presented. A conductivity technique was used to assess the critical micelle concentration (CMC) value in the aqueous phase. Batch experiments were used to understand the effect of adsorbent dose on sorption efficiency as well. Four adsorption models were also employed to make a quantitative description of equilibrium adsorption behavior of surfactant solution. For evaluating the ability of this novel biosurfactant on the surface properties, IFT values of Saponin solution were compared to those of commonly used chemical surfactants in petroleum industry. It is shown that availability and the low cost of the Zizyphus Spina-Christi extract in comparison to common chemical surfactants in petroleum industry make it economically viable for surfactant flooding.

Colloidal gas aphron (CGA) based drilling fluids, because of their non-coalescing nature, excellent capability in minimizing deep invasion, and also behaving like a flexible bridging material, are indicated for drilling permeable and fractured formations. Their unique feature is to form a solid free, tough, and elastic internal bridge in pore networks or fractures to minimize deep invasion by means of air microbubbles, which can be removed easily during the initial stage of production. CGA based fluids combine certain surfactants and polymers to create the system of microbubbles. Surfactant is used to produce the surface tension to contain the aphron as it is formed, build the multilayer bubble wall, and create interfacial tension to form a non-bonding network capable of bridging openings in permeable and fractured formations. Polymer is used as viscosifier and aphron stabilizer. The surface activity and aggregation behavior of the surfactant affects the stability and also other physico-chemical properties of generated microbubbles. Therefore, selection of a suitable surfactant is important for the generation of microbubbles with the desired rheological and filtration properties. The goal of this paper is to investigate the potential use of a new plant-derived surfactant as an aphronizer surfactant in preparation of CGA based drilling fluids for accomplishing desirable rheological and filtration properties. For this purpose, natural surfactant obtained from leaves of special tree namely Zizyphus Spina-Christi and used for preparation of aphron-based fluids. To evaluate the potential use of new plant-derived surfactant as an aphronizer, various physico-chemical properties of aphron-laden muds were investigated. To achieve the research objectives, laboratory tests of suspension generation, microscopic visualization, initial yield, filtration loss, and rheological behavior with varying concentrations of surfactant and polymer were performed. Effect of base fluid viscosity and surfactant concentration on size/size distribution of microbubbles, rheology, and yield of CGA based drilling fluids will be presented. Three rheological models, namely, Bingham Plastic, Power Law and Casson models were used for characterizing rheological properties of the muds studied.

Horizontal well completions in low permeability formations with multistage fracturing have advanced greatly over the last decade. However, achieving an optimal balance between operational and cluster efficiency remains challenging. Several studies across unconventional basins have shown less than 70% productive perforation clusters in plug-and-perf (PnP) completions, highlighting a need to improve cluster efficiency without sacrificing operation efficiency. This paper presents a case study of Wolfcamp horizontal shale wells utilizing degradable diverter particulates to successfully improve cluster efficiency and well production. Degradable diverter was implemented in five of eleven wellsacross three separate padsfor direct comparison. The diverter particulates were pre-tested in the laboratory with source water and formation cuttings samples to determine the dissolution rate and reservoir compatibility. Concentrations and deployment rate of the diverter "pill" were optimized from pressure responses during the job execution to achieve both the desired number of perforations covered and corresponding pressure increase as a leading indicator of improved cluster efficiency. Surface microseismic survey was acquired to further evaluate diverter effectiveness as compared to the offset non-diverter wells. Initial engineering design/modeling targeted 50% to 65% of perforations for diverter coverage. All diverter frac stages pumped to the expected frac design with no screen outs. Post treatment analysis were run between each pad to optimize diverter integrity for further displacement and enhancement of diversion efficiency based on observed pressure build-up. Significant pressure increases pre-and post diverter were observed in 75% of stages. Surface microseismic results measured in the first pad indicated a 50% increase in the number of microseismic events in the well with diverter along with subtle shifts in both frac geometry and orientation. In 90% of stages a noticeable correlation was perceived in surface pressure responses to microseismic events. Wider event distribution post-diversion was also noted in stages with larger surface pressure responses. Production results show wells with diverter average 10% incremental cumulative barrels of oil equivalent (BOE) production at nine totwelve months as compared to offset non-diverter wells. There is a higher prevalence of elevated GOR with the diverter wells. Average incremental oil production during the six to twelve-month time frame is 9%. Incremental impact on individual pads range from neutral to +20% at the same time frame. This paper shares the effective testing strategy to trial intra-stage diversion, engineering design work, application, analysis of diagnostic data and performance of degradable particulates in new unconventional horizontal wells. This paper also incorporates the lessons learned and best practices from field execution, real-time pressure responses, microseismic data, and production signpost results.