Drill Cuttings Research Articles

Neutralization of Drill Cuttings Discharged into the Environment During the Drilling of Oil Wells

Neutralization of Drill Cuttings Discharged into the Environment During the Drilling of Oil Wells

Heat Transfer Characteristics of Oil-Based Drill Cuttings in Thermal Desorption Chambers

Thermal desorption technologies have been extensively applied for the disposal of oil-based drill cuttings. Fluent-software-based phase changes in multiphase flow models within thermal desorption chamber temperature field simulations were examined to study the effects of oil-based drill cuttings fluid content and feed rates, nitrogen content, thermal desorption chamber length and diameter, and extraction tube position on the thermal desorption chamber and temperature field. Our results demonstrate that these factors had a considerable influence on the temperature field of the chamber, with the liquid content of the oil-based drill cuttings having the greatest influence. The heat transfer process was enhanced by appropriately increasing the diameter and length of the chamber and reasonably setting the extraction tube. When the chamber length was insufficient, there was a risk that the outlet temperature would be extremely low and the oil content of the residue would exceed the standard. The higher the feeding and nitrogen entering rates of the oil cuttings, the higher the liquid content of the oil cuttings and the lower the temperature in the chamber. Based on the heat transfer characteristics of the oil-based drill cuttings in the thermal desorption chamber, this study provides a theoretical basis for the design and application of oil-bearing cutting thermal desorption devices.

Utilization of oil-based drilling cuttings as asphalt pavement surface: Study on the mechanical characteristics and long-term environmental impact

The pollution caused by oil-based drill cuttings (OBDC) is among the major problems affecting the oil industry. In this study, six different mixing proportions of OBDC were used in preparing asphalt pavement surface, and the heavy metal leaching of the pavement surface were studied. The results indicated that with the maximum mixing proportion of OBDC reached to 4.8% (wt./wt.), the Marshall Stability, maximum flexural strain, and dynamic stability met the requirement of the technical specification for construction of highway asphalt pavements standard. Ba, Mn, Pb and Zn were the characteristic heavy metals in OBDC; heavy metal leaching experiment revealed that the cumulative leaching amount of these four heavy metals showed a similar trend, and all of them could reach to leaching equilibrium during 64 days of leaching. Among the four heavy metals, Ba and Pb showed the largest and least cumulative leaching amount, with 445.5 and 0.7 μg/kg, respectively. Overall, the full stage leaching behavior of Ba, Mn, Pb and Zn was affected by surface wash-off, but specifically, the leaching of Ba was dominated by dissolution, while Mn, Pb, Zn was controlled by diffusion at the early leaching stage. During the middle and late leaching stage, all four heavy metals turned into depletion-controlled leaching. The leaching model of Ba, Pb, and Zn were better described by the Elovich equation, while Mn fitted the second order kinetic equation more precisely. The long-term leaching prediction of cumulative leaching amount revealed that the leaching of Ba, Pb, and Zn should be concerned.

Valorization of oil well drilling cuttings as a raw material in ceramic manufacturing

This study investigates the effect of clay replacement by oil well drilling cuttings (DC) in ceramic materials manufacturing. DC was added at 0, 15, 30 and 45 wt%. The raw materials were characterized by physical, chemical, and mineralogical analyses. Ceramic specimens were produced via uniaxial pressing and sintered at a constant heating rate (5 °C/min) for 90 min at three temperatures (750, 850, or 950 °C). Then, the samples were evaluated by linear firing shrinkage, apparent specific mass, water absorption, color, and flexural strength. Ceramic materials were analyzed by X-ray fluorescence spectrometry (XRF), thermogravimetric analysis (TG), Fourier transform infrared spectroscopy (FTIR), and X-ray diffractometry (XRD/Rietveld). Environmental risk assessment of ceramic products containing DC was investigated by leaching and solubilization tests. The results allow classifying the raw and the ceramic materials as non-hazardous and inert. Ceramics consisted mainly of quartz, illite, hematite, feldspar, primary mullite, and spinel. The sintering temperatures (from 750 up to 950 °C) and the increasing DC contents (up to 45%) directly affect the mechanical properties of the red ceramic, which are suitable to produce bricks, blocks and tiles. In the analyzed scenarios, the results indicated DC as an alternative raw material environmentally appropriate for the ceramic manufacturing.

Experimental determination of gas-water relative permeability for ultra-low-permeability reservoirs using crushed-rock samples: Implications for drill cuttings characterization

Relative permeability controls fluid flow through rocks, with applications to hydrocarbon production, geologic carbon and energy storage. However, significant challenges are associated with the measurement of relative permeability for rocks with matrix permeability in the microdarcy to nanodarcy range. The primary objectives of this study are therefore to 1) propose an integrated experimental and modeling approach for gas relative permeability (krg) evaluation using crushed-rock samples and 2) perform a proof-of-concept study to demonstrate that gas–liquid relative permeability can be determined for ultra-low-permeability (unconventional) reservoir samples that have been crushed to certain grain sizes (20–35 mesh size).In this study, the water vapor ad-/desorption technique was employed to provide a wide range of water saturations (Sw). The evolution of water distribution in the shale matrix with a change in Sw was investigated by using a modified low-pressure adsorption (LPA) technique. A recently-developed numerical model was modified to estimate effective permeability to gas at each saturation level. Four clay-rich shales from the Duvernay (Canadian) and Kyalla (Australian) formations were analyzed.The vapor ad-/desorption technique provided an efficient approach to saturate the studied samples. By changing relative humidity in sealed desiccators using different salt solutions, a maximum Sw of 83% was obtained for organic-matter rich samples, and 99% for organic-matter lean shales. As interpreted using the modified LPA technique applied at different saturation levels, water is held in films in mineral-associated macro-/mesopores, and can block access to organic-matter pores through the formation of water clusters, significantly reducing the accessible organic-matter porosity and gas effective permeability. Imbibition krg decreases rapidly and significantly (over 90%) when Sw reaches approximately 0.3–0.4 for samples containing significant amounts of water-sensitive clay minerals (Kyalla #2) and TOC (Duvernay #2). Relative permeability hysteresis occurs for Duvernay #2 and Kyalla #1. Overall, the use of crushed-rock samples (non-matrix/fracture system), and application of the vapor sorption technique, results in a small amount of hysteresis.A laboratory-based method for measuring gas relative permeability of ultra-low-permeability reservoirs using crushed-rock samples is provided for the first time, with important applications to the energy and carbon capture industries.

Co-pyrolysis of oil-based drill cuttings and pinewood sawdust: Thermal behavior, synergistic effect, artificial neural network and empirical reaction model

Evaluation of pyrolysis characteristics is essential to convert the waste into various high-value products. In this study, the co-pyrolysis of oil-based drill cuttings (OBDC) and pinewood sawdust (PS) was conducted to analyze the thermal behavior, synergistic effect, and reaction mechanism. Results showed that co-pyrolysis of OBDC and PS had a positive synergistic effect, and the more the percentage of PS in the blend, the stronger the synergistic effect. The pyrolysis characteristic index D increased from 6.50 × 10-05 to 47.38 × 10-05. The apparent activation energy during the co-pyrolysis of OBDC and PS (mass ratio in 1:1) was evaluated using two model-free methods (FWO and KAS) which were 101.38 kJ/mol and 97.51 kJ/mol, respectively. The pre-exponential factors analysis found that the solid phase surface reaction occurred in the co-pyrolysis at the conversion rate of 0.05–0.35; and the co-pyrolysis underwent a complex reaction at the conversion rate above 0.35. The artificial neural network (ANN) with Logsig-Tansig transfer function and neurons number 11 × 12 × 1 had the best prediction effect on co-pyrolysis. The reaction mechanism function (f(α)) of the co-pyrolysis of OBDC and PS was (1 − α)6.2778α2.3848[−ln(1 − α)]0.3570, indicating that co-pyrolysis was the combined effects of reaction order, accelerating, and nuclei growth and diffusion mechanism.

Research on treatment of oil-based drill cuttings based on ionic liquids synergistic solvent extraction

The method of solvent extraction has a good application prospect in the treatment of oil-based drill cuttings, but the existing extractants have the high potential safety hazards of a low flash point and volatility. Therefore, this article proposes to use an ionic liquid with improved safety and strong extraction capacity to treat oil-based drill cuttings through a collaborative solvent extraction method. The extraction effect of different extractants and different ionic liquid synergistic extractants were studied, respectively. The research results showed that [IM18, H2]Br ionic liquid has a good synergistic effect with n-butanol, and the extraction rate could reach 99.14%. The experimental conditions were that the mass ratio of [IM18, H2]Br to n-butanol was 1:10, extraction time was 40 min, and the mass ratio of drill cuttings to extractant was 1:3. Under these experimental conditions, the mixed extractants can be recycled 3 times. The closed flash point of extractants increased from 35 °C to 53 °C, and the boiling point of extractants decreased from 117 °C to 90–107.3 °C. Based on this, the mechanism of ionic liquids synergistic solvent extraction was discussed.

Recovery of green solvent contaminated with petroleum hydrocarbons by selective adsorption onto granular activated carbon

Ethyl lactate (EL) has served as a promising green solvent for oil extraction from drill cuttings wastes. Its high commercial price and huge volume consumption currently pose a constraint regarding operational costs and environmental burdens. Therefore, this work aims to propose the adsorption by granular activated carbon (GAC) as a facile method for recycling the spent EL contaminated with oil. The results from batch experiments revealed that the adsorption of oil in EL was favorable and endothermic, reaching the maximum oil adsorptive capacity of 1053 mg g−1 at 35 °C. The adsorption process was best described by the Freundlich isotherm and pseudo-first order kinetic models. Oil adsorption mechanisms were mainly controlled by film diffusion, hydrophobic interaction, and coalescence. The competitive adsorption of EL onto GAC through hydrogen bonding and covalent bonding was also observed. For column adsorption, all breakthrough curves were well explained by Clark and bed depth service time models. The maximum breakthrough removal efficiency of 99.3% was achieved from the flow rate of 1 mL min−1, initial oil of 500 mg L−1 and bed height of 12 cm. The spent GAC was regenerated by heating at 350 °C, provided with a regeneration efficiency of 95% after five adsorption-desorption cycles. The payback period of using EL extraction and recovery was estimated at 1.8 years, considering secure landfill as a baseline. These findings prove the industrial applicability of GAC adsorption for solvent recovery and promote EL as a more economically feasible solvent for greener management of oil-contaminated drill cuttings.

Organic Matter Assessment and Paleoenvironmental Changes of the Middle Jurassic Main Source Rocks (Khatatba Formation) in the North Western Desert, Egypt: Palynofacies and Palynomorph Perspectives

The Middle Jurassic in the north Western Desert, Egypt, was a time of complex tectonics and increased environmental perturbations attributed to the predominant sedimentation of organic carbon-rich fine siliciclastic and carbonate deposits of the Khatatba Formation. Although some studies have addressed the hydrocarbon potential and source rock characteristics of the Khatatba Formation, a regional-scale investigation of the prevalent paleoenvironmental conditions and organic matter characteristics is still necessary. In this study, the Khatatba Formation is investigated for detailed palynofacies analysis and palynomorph composition to assess organic matter kerogen types and reconstruct the depositional paleoenvironmental patterns on a regional scale. For this purpose, 116 drill cuttings were collected from five wells in the Matruh, Shushan, and Dahab-Mireir Basins. Moderately diverse assemblages of spores, pollen, and dinoflagellate cysts are reported. Age-diagnostic dinoflagellate cysts, including Adnatosphaeridium caulleryi, Dichadogonyaulax sellwoodii, Korystocysta gochtii, Wanaea acollaris, and Pareodinia ceratophora, along with occasional records of Systematophora areolate and Systematophora penicillate, defined a Bajocian–Callovian age. Based on particulate organic matter (POM) composition, four palynofacies assemblages (PFAs) are identified. PFA-1 is the most common within the Khatatba Formation in the five studied wells. It contains high proportions of phytoclast fragments versus low contents of amorphous organic matter (AOM) and palynomorphs and is defined by a gas-prone kerogen Type III. PFA-2 is comprised of moderate abundances of AOM and phytoclast characteristics of oil-prone kerogen Type II. PFA-3 is dominated by phytoclasts and moderate to low proportions of AOM and palynomorphs of kerogen Type III, whereas PFA-4 consists of AOM and palynomorphs defining kerogen Type II. PFA-1 indicates predominant deposition in proximal active fluvio-deltaic sources to marginal marine conditions with enhanced contributions of terrestrial/riverine influx. PFA-2 and PFA-3 reveal deposition under an enhanced dysoxic to anoxic proximal inner neritic shelf due to the abundant occurrences of spores and coastal to shallow marine dinoflagellate cysts. PFA-4 suggests deposition under enhanced suboxic to anoxic distal inner neritic conditions because of enhanced AOM and abundant proximate and some chorate dinoflagellate cysts. Thus, the Middle Jurassic experienced a predominantly marginal to shallow water column in this part of the southern margin of the Tethyan Ocean where the Matruh, Shushan, and Dahab-Mireir Basins were located.

Application of Drill Cuttings Recovery Technology with the Production of Building Material on the Example of a Deposit in Western Siberia

A technology for disposing drill cuttings with the production of building materials that meet existing standards, are environmentally friendly and cost-effective on an industrial scale is presented. The article describes the building materials production which allows the disposal of drilling cuttings in parallel with the drilling of oil wells to reduce the time and area of the allotted territories for the construction of waste storage facilities.

Study on Pyrolysis of Shale Gas Oil-Based Drilling Cuttings: Kinetics, Process Parameters, and Product Yield.

The main reaction range (350-550 °C) of oil-based drilling cutting (OBDC) pyrolysis was studied by a thermogravimetric analyzer and a vacuum tube furnace. The average activation energies calculated by four model-free methods were 185.5 kJ/mol (FM), 184.16 kJ/mol (FWO), 166.17 kJ/mol (KAS), and 176.03 kJ/mol (Starink). The reaction mechanism was predicted by the Criado (Z-master plot) method. It is found that a high heating rate is helpful to predict the reaction mechanism, but it cannot be described by a single reaction model. Under the conditions of target temperature higher than 350 °C, residence time higher than 50 min, laying thickness less than 20 mm, and heating rate lower than 15 °C, the residual oil content is lower than 0.3% and the recovery rate of mineral oil is higher than 98.43%. Solid phase products accounted for more than 70%, reached the maximum 17.04% at 450 °C, and then decreased to 15.87% at 500 °C. Aromatic hydrocarbons, as coking precursors, are transformed from a low ring to a high ring. Recycled mineral oil can reconfigure oil-based mud (OBM). The research results can provide a theoretical basis for process optimization.

A Review of Optimisation of Transportation of Drill Cuttings Waste

Transportation and monitoring of oil and gas operations require advanced logistics supply chain management. This paper adopts the desktop study research method, using credible pieces of literature such as textbooks and online journals and articles, to identify preferable waste management options for transportation drill cuttings wastes and improving the oil and gas business. Findings reveal that haulage of drill cuttings is regulated differently depending on the environmental compliance requirements locally and internationally. Though challenging, the shipment of drill cuttings from cradle to grave can be improved, based on the localised monitoring mechanisms and possibly, the adaptation of spatial technologies which inversely progress logistic outcomes.

Chelativorans petroleitrophicus sp. nov., a paraffin oil-degrading bacterium isolated from a mixture of oil-based drill cuttings and paddy soil.

We isolated a paraffin oil-degrading bacterial strain from a mixture of oil-based drill cutting and paddy soil, and characterized the strain using a polyphasic approach. The Gram-positive, aerobic, rod-shaped and non-spore-forming strain (SCAU 2101T) grew optimally at 50 °C, pH 7.0 and 0.5 % (w/v) NaCl. Phylogenetic analysis based on 16S rRNA gene sequence indicated that the strain represented a distinct clade in the genus Chelativorans, neighbouring Chelativorans intermedius LMG 28482T (97.1 %). The genome size and DNA G+C content of the strain were 3 969 430 bp and 63.1 mol%, respectively. Whole genome based phylogenomic analyses showed that the average nucleotide identity and digital DNA-DNA hybridization values between strain SCAU 2101T and C. intermedius LMG 28482T were 77.5 and 21.2 %, respectively. The major respiratory quinone was Q-10. The dominant fatty acids were C19 : 0 cyclo ω8c (50.6 %), summed feature 8 (C18 : 1 ω7c and/or C18 : 1 ω6c; 22.5 %) and C18 : 0 (13.8 %). The polar lipids of the strain included phosphatidylethanolamine, phosphatidylmonomethylethanolamine, phosphatidylglycerol, phosphatidylcholine and diphosphatidylglycerol. Based on the results, strain SCAU 2101T was considered to represent a novel species in the genus Chelativorans, for which the name Chelativorans petroleitrophicus sp. nov. is proposed. The type strain is SCAU 2101T (= CCTCC AB 2021125T=KCTC 92067T).

A novel supplementary cementitious material based on calcined drill cuttings with waste glass to accelerate cement hydration

Water-based drill cuttings, a solid waste from oil and gas fields, have been utilized as supplementary cementitious material after calcination and grinding. However, the comparatively low silica of water-based drill cuttings limits the replacement of ordinary Portland cement. The issue can be solved by mixing water-based drill cuttings with waste glass residue, which contains high silica and can melt during calcination. This paper investigates the effects of calcination temperature and waste glass residue on cured specimens' compressive strength. Experimental results indicated that the best product was obtained by mixing 20wt% waste glass residue and 80wt% water-based drill cuttings, calcinating at 1000 °C, then sieving through 1600 mesh. The 90-day compressive strength of the specimen was 57.12MPa, which was better than the 51.19MPa of the pure cement group. X-ray fluorescence spectroscopy and scanning electron microscopy showed that the waste glass residue melted above 800 °C, which increased the product's glass phase and improved its internal structure. Besides, the Isothermal conduction calorimeter and X-ray diffraction spectroscopy indicated that the hydration process has an advanced hydration rate, high total heat release in the early stage, and novel crystalline Chloritoid generation, all of which can enhance mechanical performance.

Реакция семян культур-фитомелиорантов при условии природного и техногенного засоления почв и грунтов

Abstract. The purpose of the study is to establish the optimal and critical values of different chemisms and the degree of salinity and the corresponding indicators of osmotic pressure, pH of the medium for the germination energy and germination of seeds of alfalfa and sweet clover. Objectives of the study are to identify the parameters of 50 and 99 % death of seeds of the studied crops, taking into account the chemistry and degree of salinity, to determine the most toxic water-soluble salts in solonetzic soils and drill cuttings; to identify the degree of participation of osmotic pressure and pH of the medium for the studied options, to conduct a comparative study of chemisms and the degree of their salinity on the germination and germination of seeds of phytomeliorants. Methods. The experiments were carried out in laboratory conditions. Seeds of sweet clover of the Alsheevskiy variety and alfalfa of the Yaroslavna variety were used as the object of the study. The energy and germination of seeds were determined according to GOST 12038-84. Scientific novelty. For the first time, the parameters the average lethal dose and the dose is absolutely lethal for sweet clover and alfalfa seeds were established in relation to different salinity chemisms, represented by one easily soluble salt, identical to soil and technogenic salinization. The parameters of osmotic pressure and pH of the medium for the average lethal dose and the dose is absolutely lethal were determined for each salinity chemistry. Results. It was found that a low concentration of MgSO4 (up to 0.3 %) did not reduce the energy and germination of seeds of sweet clover and alfalfa. Sodium neutral salts (Na2SO4, NaCl) led to the loss of seed germination of sweet clover and alfalfa (the dose is absolutely lethal) at a salinity degree of 2.0–2.9 %, which corresponds to a high osmotic pressure of 8.9–13.9 atm. Sweet clover seeds had a higher capacity for maximum salinity. Under soda salinity (Na2CO3, NaHCO3), 50 % death of sweet clover and alfalfa seeds corresponded to salinity levels of solonetzes and drill cuttings of 0.09 and 0.25 %. The phenomenon corresponding to the dose is absolutely lethal was noted here, respectively, at the level of salinity of soils and drill cuttings of 0.42 and 0.95 %. It is important to take into account the average lethal dose indicator when recultivating solonetzes and drill cuttings in order to establish seeding rates and select phytomeliorant crops.

Standardization of Particle Size for Floating Particle Wettability Measurement for Carbonate Rocks.

Misrepresentation of the wettability of a reservoir can lead to potentially low ultimate hydrocarbon recovery resulting in substantial economic losses. At the same time, it is impossible to determine the wettability of a reservoir across its length and breadth on a continuous basis using standard procedures. This work presents the development and standardization of a quick, easy, and low-cost wettability measurement method using the adherence tendency of rock particles in the oil or aqueous phase. The most important aspect of this study was establishing the optimum particle size for sustained floatation and balancing the buoyancy and gravity effect. The results show that the particles sink with a larger than optimum particle size because of the gravity effect. Similarly, the particles would float if they are smaller than optimum due to buoyancy and viscosity advantages. A new scale is designed, and the midpoint analysis shows that a 63-90 μm particle size is the ideal size range for the carbonate reservoir's wettability measurements, as the midpoint of the size distribution coincides with the standard Amott-Harvey (A-H) index. However, this size range is found to be wider for oil-wet particles. The floating particle method has several advantages over the established methods once standardized against a reliable process. Not only is the process fast but it can be performed with basic laboratory tools and does not require a high skill set. Most importantly, reliable wettability information can be obtained from drill cuttings and core fragments, enabling the determination of reservoir wettability on a continuum basis and not as a point basis, thus providing a more reliable average value, particularly for heterogeneous and unconsolidated reservoirs.

Optimization of cuttings slurry system for re-injection of oil-based drilling cuttings

ABSTRACT Cuttings re-injection technology has become a preferential choice of the treatment of oil-based drilling wastes in offshore oilfields. However, there are relatively few formulation designs and performance tests for re-injection slurry systems. In this study, an oil-based drilling cutting re-injection fluid system was developed. The relationship between the suspension and rheology of the re-injection fluid and time is obtained by using the experimental method of sectional measurement. The laboratory re-injection fluid preparation procedures are introduced in detail. The final optimized cutting slurry has a formula for drilling cuttings content of 15% −35%, guar gum (GG) content of 0.4% as the main additives, and auxiliary additives such as 0.3% fluid loss agent and 0.3% defoamer. The experimental results show that the re-injection fluid has good suspension and rheology. After standing at 60°C for 24 h, the sedimentation density difference is only less than 0.12 g/cm3, and the viscosity is 51–66 mPa·s. The cross-linked structure of the internal molecules of the fluid system remains stable, and the viscosity does not decrease obviously to the increase in time. The overall performance of the optimized re-injection fluid satisfies the requirement of the operator.

A life cycle assessment of drilling waste management: a case study of oil and gas condensate field in the north of western Siberia, Russia

Oil production is currently impossible without drilling wells, so millions of tons of drilling waste contaminated with oil, chlorides, and heavy metals are generated every year in Russia alone. This article presents the results of a comparative life cycle assessment of water-based drill cuttings management technologies applied in Russia, including disposal, solidification, and reinjection. Life cycle assessment of the drilling waste management was performed using OpenLCA software, Ecoinvent 3.8 database and ReCiPe Midpoint (H) impact assessment method. Fossil depletion, climate change and human toxicity were chosen as impact categories. Data from oil producing companies on the composition of drilling waste and information from drilling waste treatment companies on the technologies and reagents used were also applied. To compare alternative technologies the following scenarios were compared: Scenario 0 «Landspraying», scenario 1 «Disposal», scenario 2 «Solidification» (scenario 2a – in a waste pit, scenario 2b – without a waste pit), and scenario 3 «Reinjection». Sensitivity analysis was performed to test for variations in results for oilfields located in different regions and for differences in mass of reagents used. The environmental impact of scenario 0 (landspraying) depends mostly on drilling waste composition, which is largely determined by human toxicity that can differ from 17 up to 2642 kg 1,4-DCB-eq per 1 t of drill cuttings, when for other scenarios it is from 24 up to 73 kg 1,4-DCB-eq per 1 t of drill cuttings. It means, that drilling waste landspraying is the best option only if the level of pollutants in the waste is very low. Among the other scenarios of drill cuttings management aimed at isolating pollutants from the environment, solidification technologies have the greatest environmental impact, primarily due to their use of binders. Among all scenarios, 2a and 2b have the biggest environmental effect in most impact categories. The production of cement and lime for drilling waste solidification was the main contributor to fossil depletion (64% of the total amount for scenario 2a and 54% for scenario 2b), and greenhouse gas emissions (49% of the total amount for scenario 2a and 70% for scenario 2b). However, the application of soil-like material (solidified drill cuttings) as an inert ground in swampy areas can make migration of heavy metals possible. Scenario 3 (reinjection) is associated with the least impact on the environment and the main contributor is electricity production (75% of greenhouse gas emissions). Sensitivity analysis shows that oilfield location does not affect the data for reinjection, but the impact assessment changes up to 60% for drill cutting disposal due to different waste pit design depending on permafrost and groundwater levels. Differences in the mass of used cement and lime change results for solidification scenarios considerably (up to 80%).

S-Wave Velocity Forecasting Using Drill Cuttings and Deep Hybrid Neural Networks: A Case Study on a Tight Glutenite Reservoir in Mahu Sag, Junggar Basin

S-wave velocity (Vs) is a critical petrophysical parameter for reservoir characterization. It is desirable to predict Vs based on conventional logging data, but the logging cost is high. Therefore, a deep hybrid neural network coupling the convolutional neural network (CNN), Stacked gated recurrent unit (SGRU) is proposed to predict the Vs, where the inputs to the model are drill cutting features. In the proposed CNN-SGRU hybrid model, CNN is adopted to capture the spatial features from the input data, and SGRU is used to extract the temporal patterns of variation from both the forward and backward directions. To illustrate the prediction effect, the glutenite reservoir in the Baikouquan Formation of Mahu Sag, Junggar Basin is taken as an example. Mineral and pore information of drill cuttings, including siliciclastic content, clay content, quartz content, and void area ratio is chosen as the input data of the CNN-SGRU hybrid model. Three indices are used to quantitatively evaluate the prediction performance, including Mean absolute percentage error (MAPE), Root mean square error (RMSE), and Mean absolute error (MAE). The results show that the prediction accuracy of the proposed model is higher than that of the Xu-White model, CNN, and GRU. Furthermore, the results indicate that drill cuttings can replace logging data to predict Vs.

Quantitative assessment of rock lithology from gamma-ray and mud logging data

The data on vertical variations of the rock lithological content along the geological profiles of boreholes are essential for interwell correlation, geological or hydrodynamic modeling, optimization of drilling process, etc. There are direct (investigation of core samples) and indirect (processing and interpretation of well-logging data) methods applied in petroleum engineering to determine rock lithology. Both approaches have several limitations (such as low quality of logging data in case of washouts, low frequency of sampling of drill cuttings, limited number of wells drilled with coring, etc.) calling for alternative approaches to determine rock lithological content along the borehole. One of the alternative solutions could be application of mud logging (drilling and mud gas data) due to the strong physical background of interrelations between drilling and mud gas data on one side and rock lithology on the other. Literature review shows that many of existing machine learning-based solutions assume application of mud logging data mainly for rock typing (qualitative assessment of rock lithology). Concurrently, many applied problems require quantitative data on rock lithology (volumetric concentrations of rock lithological components). To fill this gap, we assessed the capabilities of mud logging data for quantitative characterization of rock lithology. We proposed a new algorithm for the task at hand relying on special data processing and machine learning algorithms. As an input data we used drilling, mud gas, and gamma-ray data. The results of the developed algorithm application for three industrial wells confirmed the effectiveness of the developed algorithm. During our research we compared the performance of XGBoost algorithm and 1-D convolutional neural network. Obtained results allow concluding that the obtained regression models and developed algorithm exhibit good generalization ability providing the average total prediction uncertainty on unseen well of less than 0.15 c.u.