Experimental investigation on plugging performance of nanospheres in low-permeability reservoir with bottom water

With oil and gas drilling going deeper, wellbore instability and high-temperature failure of drilling fluid become more and more serious. Using plugging agents to block micropore and microfracture formation is the key to minimizing filtrate invasion into the formation, stopping pressure transfer, and reducing downhole accidents. At present, the most commonly used plugging agents are hardly able to satisfy the plugging demands of ultrahigh-temperature formation. A high thermoresistant nanopolymer microsphere (PSDA) was prepared by soap-free emulsion polymerization. The study indicated that the starting thermal breakdown temperature of PSDA was 316 °C. At the indoor temperature, the median particle size (D 50 ) was 177 nm. After aging at 240 °C, D 50 reduced to 152 nm. Meanwhile, it can be observed from the scanning electron microscope (SEM) that the particle size of PSDA has little difference before and after high-temperature effect, indicating that PSDA possesses excellent stability against high temperatures. The turbiscan stability index (TSI) values of 3 wt % PSDA suspensions were less than 0.1, which has good dispersion stability. The blocking performance of the PSDA suspension was studied using 100 and 300 nm microporous filter membranes as blocking media. With the addition of PSDA in the drilling fluid, API filtration gradually decreases. When the addition amount was 3 wt %, after aging at 240 °C, the reduction rate of API filtration was 57.6%, and the filter cake formed was dense. At the same time, a great quantity of microspheres on the filter cake surface can be observed in the SEM picture, indicating that PSDA can resist high temperatures at 240 °C and has good filter loss reduction performance. Compared with emulsified bitumen, nanopolyester (NP-1), and silicone sol (JN-40), PSDA has the best filtration reduction performance. PSDA holds promise as an excellent temperature-resistant plugging additive for water-based drilling fluid.

Section: Resultssupporting

confidence: 57%

“…after entering the pore space, which is a hybrid plugging mechanism. 33,34 The plugging schematic is shown in Figure 16.…”

Section: Evaluation Of Medium-pressure Sand Bed Pluggingmentioning

confidence: 99%

Preparation and Evaluation of Nanopolymer Microsphere Plugging Agents for Ultrahigh-Temperature Water-Based Drilling Fluids

Xu,

Sun,

Liu

et al. 2023

“…In recent years, NMR experiments have been widely used in the petroleum industry, especially in the investigation of the pore structure and fluid flow characteristic. ,, The experiment was conducted to investigate the microscopic flow characteristic of nanospheres at the microscale. The pore structure was classified by relaxation time, and the flow characteristic was obtained by the H-signal intensity by NMR …”

Section: Methodsmentioning

confidence: 99%

“…Unconventional oil has gradually become a hot topic in global oil exploration and development, with tremendous development potential, especially low-permeability and shale oil reservoirs. − Hydraulic fracturing is a common reservoir reconstruction method, which can greatly improve the flow capacity of the formation and enhance the recovery efficiency. − However, the high-permeability channel after fracturing results in the water intrusion, which seriously reduces oil production. To solve this problem, polymer microspheres are widely used and have been well recognized. , They have low cost and are simple, which are formed by polymerization of monomers under the action of an initiator and have good expansibility. Due to the injection pressure difference, injected polymer microspheres can migrate to the depth of the formation and preferentially enter the pores with large radius and good connectivity .…”

Section: Introductionmentioning

confidence: 99%

A Systematic Method to Investigate the EOR Mechanism of Nanospheres: Laboratory Experiments from Core to Micro Perspective

Wang

Yang

et al. 2023

Self Cite

Nanospheres have been used as an available plugging material to solve the problem of water intrusion, which is of crucial importance to enhanced oil recovery (EOR). However, the microflow of nanospheres in a lowpermeability reservoir is complex, and its plugging performance and EOR mechanism need to be further investigated by a variety of experiments. In this paper, the expansion experiments were given priority to explore the water absorption and salt tolerance of nanospheres. The displacement experiments were conducted to investigate the plugging performance of nanospheres at the core scale. The flow characteristic and EOR mechanism of nanospheres at the microscale were revealed by nuclear magnetic resonance (NMR) experiments and microfluidic experiments. Expansion and displacement experiments results demonstrate that high salinity inhibits the expansibility and agglomeration of nanospheres, and the formation damage and plugging performance of nanospheres should be comprehensively considered. The suitable particle size of nanospheres should be optimized for field application. As for the microscale, NMR experiments revealed that nanospheres would first enter the large pore and then enter the middle and small pores. In microfluidic experiments, the oil recovery increased by 23.02% original oil in place after the injection of nanospheres. The systematic and comprehensive investigations of expansion property, plugging performance, flow characteristic, and EOR mechanism of nanospheres were conducted from core to microscale, which yielded significant insights into preventing water intrusion and enhancing oil recovery.

“…Global tight oil reserves are abundant, but most tight reservoirs still face the difficulty of high-efficiency development, which is characterized by rapid production decline and low oil recovery. , Numerous studies have proved the feasibility of CO 2 injection to enhance oil recovery for tight reservoirs, − so it is crucial to utilize CO 2 storage combined with enhanced oil recovery (EOR) for tight reservoir development. Due to the extremely small pores of tight reservoirs, gas displacement sometimes fails to instantly establish an effective displacement system or causes serious gas channeling. − CO 2 huff and puff (huff-n-puff) becomes an important method of EOR and CO 2 storage for tight oil reservoirs. − …”

Section: Introductionmentioning

confidence: 99%

Experimental Investigation on the CO₂ Effective Distance and CO₂-EOR Storage for Tight Oil Reservoir

Xie

et al. 2022

Self Cite

CO 2 underground storage is an important approach to reduce carbon emissions; meanwhile, the combination of CO 2 storage and economic benefits can further promote the long-term development of carbon neutrality. Global tight oil reserves are abundant, but the depletion development of most tight reservoirs is unsatisfactory. Therefore, it is crucial to utilize CO 2 storage combined with enhanced oil recovery (EOR) for tight reservoir development. At present, there are few experimental studies on the CO 2 effective distance and CO 2 -EOR storage of huff-n-puff in tight reservoirs. In this paper, the CO 2 effective distance and the evolution of saturation profiles in tight cores are first investigated, and CO 2 -EOR storage is quantitatively evaluated for CO 2 huff-npuff in tight reservoirs based on CT and nuclear magnetic resonance technology. Meanwhile, the influences of oil composition and permeability on the effective distance and CO 2 -EOR storage are further investigated. The results indicate that the increase of CO 2 effective distance gradually slows down with time, and the decrease of permeability significantly reduces the effective distance. Increasing amount of oil is mainly produced in larger pores, which is more than twice of that in smaller pores. CO 2 -EOR storage experiments quantify that the CO 2 storage ratio for a 0.22 × 10 −3 μm2 core is up to 72.31% under different depressurization conditions (12, 8, and 0.1 MPa). With the decrease in production pressure, oil recovery gradually increases, while the CO 2 storage ratio decreases, indicating that there is a collaborative optimization to maximize the oil production and CO 2 storage ratio. Comparison experiments reveal that the oil composition (replaced by fluorocarbon oil) has little influence on the effective distance and CO 2 -EOR storage, while the influence of permeability is significant. The CO 2 effective distance determines the sweep efficiency, so increasing effective distance is essential to enhance oil recovery and CO 2 storage. This research is of great significance for CO 2 utilization and CO 2 storage in tight reservoirs.