Application of Solid Paraffin Inhibitor in Fracturing of Kuqa Ultra Deep High Pressure and High Wax Content Tight Condensate Gas Reservoir

The buried depth of gas reservoir B is more than 6700m, the thickness of reservoir is about 180m, the porosity of reservoir matrix is mainly 5.0% - 7.0%, with an average of 6.3%, and the permeability of reservoir matrix is mainly 0.01-0.1mD, The average production capacity of the three wells is 0.08mD, the formation pressure is 116-126MPa, the formation temperature is 124-131°C, the wax content of the condensate oil is high, and the average wax content is 16.9%. In the early stage, the natural productivity of the three wells was low, and the daily gas production was 120000-180000 cubic meters after stimulation. During the production process, the wellhead temperature was 20°C-25°C, the wax freezing temperature was 35°C, and the wellbore wax plugging was serious, The wellbore was blocked, the gas well was forced to shut down, and the reserves of 100 billion cubic meters were unable to be used, so it was necessary to explore new wax control technology. Through investigation, a new type of solid particle paraffin inhibitor is introduced, which can enter the artificial fracture with proppant during fracturing. When the condensate gas passes through the fracture, it washes the solid paraffin inhibitor which enters with proppant, and becomes the condensate gas containing paraffin control components.Therefore,it is not easy to form wax after entering the wellbore, which makes the problem of wellbore paraffin formation change from "passive control" to "active control". Referring to the relevant experimental standards, the conductivity, crushing test, solid paraffin inhibitor and fracturing fluid compatibility test were carried out. The existing test standards of wax freezing point are all for waxy oil under normal pressure, but not for condensate gas. A set of innovative experimental method is designed to successfully test the wax freezing point of condensate gas containing wax control components, and obtain the wax control effect under different ratios of wax control agent and proppant, so as to optimize the amount of wax control agent used in the experiment. The results show that the solid paraffin inhibitor has good dispersibility and suspension, and has little influence on the conductivity of sand filled fractures. The paraffin control effect on condensate oil and gas in this block is good. The wax freezing point can be reduced by about 12°C-18°C, and the optimal dosage is proppant 1%-2%. Field test was carried out in B gas reservoir. After fracturing, 5mm nozzle was used for production, tubing pressure was 83.6MPa, wellhead temperature was 28.8°C, daily oil production was 10.72 cubic meters, daily gas production was 217000 cubic meters, wellhead temperature was lower than wax freezing temperature in this area. At present, it has been in production for 6 months, and there is no wax deposit in wellbore. The successful test of solid paraffin inhibitor in the fracturing of Kuqa ultra deep high pressure and high wax content tight condensate gas reservoir provides a powerful technical reference for the wellbore flow guarantee of condensate gas reservoir.

Asphaltene Inhibition and Flow Improvement of Crude Oil with a High Content of Asphaltene and Wax by Polymers Bearing Ultra-Long Side Chain

A high content of asphaltene and wax in crude oil leads to difficulties in the recovery and transportation of crude oil due to the precipitation of asphaltenes and the deposition of waxes. Comb-like polymers were found to be capable of inhibiting the aggregation of asphaltenes and crystallization of waxes. In this work, comb-like bipolymers of α-olefins/ultra-long chain (C18, C22 and C28) alkyl acrylate were synthesized and characterized by FT-IR and 1H NMR spectra. The results show that, for a model oil containing asphaltene, the initial precipitation point (IPP) of asphaltene was prolonged by UV, and the asphaltene particle size was reduced after adding the biopolymers, as revealed by dynamitic light scattering (DLS). The bipolymer containing the longer alkyl chain had a better asphaltene inhibition effect. However, DSC and rheological results show that the wax appearance temperature (WAT) of the typical high asphaltene and high wax content of crude oil was obviously reduced by adding bipolymers with shorter alkyl chains. The bipolymer (TDA2024-22) with a mediate alkyl chain (C22) reduced the viscosity and thixotropy of the crude oil by a much larger margin than others. Compared with the previously synthesized bipolymer with phenyl pendant (PDV-A-18), TDA2024-22 exhibited a better performance. Therefore, bipolymers with appropriate alkyl side chains can act as not only the asphaltene inhibitors but also wax inhibitors for high asphaltene and wax content of crude oil, which has great potential applications in the oil fields.

Uncovering Mysteries of Waxphaltenes: Meticulous Experimental Studies of Field and Lab Deposits Unveil Nature of Wax-Asphaltene Intermolecular Interactions

In recent years, the utilization of modern sampling tools provided access to the field deposits from several offshore and onshore wells producing asphaltenic crudes. Compositional analysis of field deposits revealed the presence of asphaltenes and wax as major fractions, while system conditions traditionally implied precipitation and deposition of asphaltenes only. Most of the previous studies on organic deposition have been conducted with the key assumption that aggregation and precipitation of wax and asphaltene occur independently. A few researchers investigated the solubility parameter's alteration, but they did not incorporate waxes found in the oilfield deposits. This study aims to investigate the nature of "waxphaltenes"; from intermolecular interactions between asphaltenes and wax in samples collected from fields and made in the laboratory. Asphaltenes samples were extracted and fully characterized by proton nuclear magnetic resonance (NMR) and Fourier-transform infrared spectroscopy (FTIR). Paraffin waxes were identified using gas chromatography (GC), differential scanning calorimetry (DSC), NMR, and FTIR. Precipitation tests of asphaltenes with n-heptane at high temperature were performed both in the presence and absence of wax; GC, NMR and FTIR techniques evaluated the precipitates and the material dispersed in solution. It was found that asphaltenes co-precipitated with waxes even at higher temperatures than the normal wax appearance temperature (WAT) of the crude oil or the model solutions and that long and medium size paraffin waxes had higher tendencies to coprecipitate with asphaltenes than either short chain or very long chain paraffin hydrocarbons. The results also indicated that the amount of wax that co-precipitates with asphaltenes was more related to asphaltene structure but is independent of the asphaltenes or wax content. Heteroatoms played an important role in the interactions between wax and asphaltenes during precipitation and separation.

Investigation about wetting ability (surface tension) of water used for preparation of pesticide solutions

<p class="042abstractstekst">The investigation about surface tension of water used for preparation of pesticide solutions reveals it is quite diverse and changeable without any logical correlation towards location, time, and type of water source. Moreover, spraying with solutions with lower surface tension give bigger flow rates due to the lower resistance of fluid to the nozzles. The conducted trials show that plant surfaces with more rough texture require to be sprayed with pesticide solutions with lower surface tension. The wax content of the surfaces has no significant impact on surface tension requirement.</p><p> </p>

Influence of Hydrostatic Pressure on the Formation of Voids in Gelled Crude Oil

Production of waxy crude oil from offshore fields has increased in the last decade. However, the operation is being challenged with the high wax content of crude oil that tends to precipitate at lower temperature. This paper presents the effects of hydrostatic pressure on the voids formed in waxy crude oil gel. A flow loop rig that simulates offshore waxy crude oil transportation was used to produce the gel. A Magnetic Resonance Imaging of 3-Tesla system was used to scan the gelled samples in horizontal and vertical pipes. The hydrostatic pressure effect was found to be most significant near the pipe wall as a change in percent voids volume of 0.53% was observed at that region. In particular, the voids volume reduction was more pronounced in the lower half side of the pipe. The total volume of voids in the vertical pipe was lower than that in the horizontal pipe, and this suggests that the gel in the vertical pipe became denser due to the effects from the hydrostatic pressure. Conversely, the voids volume around the pipe core in the vertical pipe was higher when compared to that in the horizontal pipe. The change in voids volume near the pipe core and wall shrunk to a minimum and converged to 0.18% voids volume at larger duration of the hydrostatic effect. Further, hydrostatic pressure was observed to have significant influences for higher duration making the void size to be distributed across and along the pipeline; however, it was found to have insignificant effects on voids size distribution for smaller duration. The findings of this study can help for better understanding of voids formation in vertical pipelines that would further assist in developing a model predicting restart pressure accurately.

Justification of a comprehensive technology for preventing the formation of asphalt-resin-paraffin deposits during the production of highlyparaffinic oil by electric submersible pumps from multiformation deposits

Severe problems accompany the production of abnormal oils with high pour point (with a paraffin content of over 30% by weight) in Kraynego Severa, Russia, due to the intensive formation of asphalt-resin-paraffin deposits (ARPD) in the bottom hole zone of the productive formation and downhole equipment. Possessing many advantages, the existing methods and technologies for coping with ARPD cannot fully solve this problem. As a result, complications arising from the production of high-wax oils lead to a significant decrease in oil production, a reduction in the production wells' maintenance and intertreatment periods, and an increase in dewaxing unit operating costs. The obtained results of theoretical and laboratory studies show that one of the promising approaches to improve the efficiency of wells equipped with electric submersible pumps when exploitation of abnormal oils with high pour point from multilayer deposits of the Timan-Pechora oil and gas province is the use of the new integrated technology based on the joint production of abnormal oil with high pour point with the oil, characterized by a lower wax content and the manifestation of structural and mechanical properties, in conjunction with regulating the parameters of the electric submersible pump. In this paper, the authors also describe a promising scheme of downhole equipment for the simultaneous-separate production of high-wax oil from multilayer deposits. The proposed downhole equipment allows us to separate the perforation zones of two productive formations using a packer-anchor system during simultaneous-separate exploitation of the formations by a double electric submersible pump installation.

Clay Nanotube Immobilization on Animal Hair for Sustained Anti-Lice Protection

Topical administration of drugs is required for the treatment of parasitic diseases and insect infestations; therefore, fabrication of nanoscale drug carriers for effective insecticide topical delivery is needed. Here we report the enhanced immobilization of halloysite tubule nanoclay onto semiaquatic capybaras which have hydrophobic hair surfaces as compared to their close relatives, land-dwelling guinea pigs, and other agricultural livestock. The hair surface of mammals varies in hydrophobicity having a cortex surrounded by cuticles. Spontaneous 1–2 µm thick halloysite hair coverages on the semi-aquatic rodent capybara, non-aquatic rodent guinea pig, and farm goats were compared. The best coating was found for capybara due to the elevated 5 wt% wax content. As a result, we suggest hair pretreatment with diluted wax for enhanced nanoclay adsorption. The formation of a stable goat hair coverage with a 2–3 µm halloysite layer loaded with permethrin insecticide allowed for long-lasting anti-parasitic protection, enduring multiple rain wettings and washings. We expect that our technology will find applications in animal parasitosis protection and may be extended to prolonged human anti-lice treatment.

New perspectives on the source rock facies of the Andaman Trough, offshore North Sumatra based on the latest onshore oil sampling and analysis

The Andaman sub-basin, located offshore Aceh Indonesia, is considered to be one of Indonesia’s most underexplored basins, despite its proximity to the giant gas and condensate fields of Arun, NSO A, NSO J and South Lhok Sukon, where in excess of 6 MMboe has been produced to date. The understanding of the Petroleum System in the offshore Andaman Trough, has historically been challenged by poor imaging of the basin architecture and limited penetration and retrieval of source rock intervals and hydrocarbon fluids for analysis. Mubadala Petroleum, as operator of the Andaman I PSC, conducted a geological field study to collect multiple oil samples from fourteen (14) onshore traditional wells across the Bireun and Aceh Timur Administrative District (Figure 1). Those samples were analyzed in laboratory for their physical properties and parameters derived from those analyzes where integrated to fully characterize oils produced in the onshore Aceh area and establish the organofacies and maturity of their source facies precursors. The results were then used as calibration for the analysis and subsurface modeling of the offshore petroleum system of the Andaman sub-basin. Previous authors have postulated that Late Oligocene to Early Miocene marine shales were the main source rocks for oil in the Andaman Trough. Oil samples collected onshore as part of this study however, were sourced by peak to late mature oil-prone lacustrine source rock facies, yielding high API (42.7 – 50.8°), low pour point, low sulphur, and low wax content fluids. Integration of these findings with the upgraded tectono-stratigraphic framework provided by the 2019 MC3D survey, reprocessed multi-vintage 2D, and reinterpretation of biostratigraphic analysis, has enabled the delineation of a postulated Paleogene lacustrine source rock facies in the Andaman Trough. This model does not preclude the potential of other source rock facies to be present and active within the Andaman Trough, including the gas-prone fluvial Eocene-Oligocene Parapat Formation, but it supports the possibility that oil may have been generated in the Andaman Trough.