Role of high-density brines in reservoir development stages:A review

High-density brines have been recognized beneficial for oilfield applications,with various key areas such as drilling,completion and formation evaluation.High-density brines can play a critical role in the development and production of oil and gas reservoirs during the primary,secondary,and tertiary recovery phases.High-density brines can enhance the mobility and recovery of the oil in the reservoir by controlling the density and viscosity.However,a less attention has been given to the application of high-density brine in the area of reservoir development.This review is shedding light on a concise overview of reservoir development stages in association with the recovery mechanisms.In addition,most possible applications of high-density fluids have also been reviewed in the field of the reservoir development.In summary,this review state that high-density brines can be used to stimulate reservoirs by hydraulic fracturing during the primary recovery phase.However,the risk of increased interfacial tension,which relies on the density difference of two fluids,can trap more residual oil relative to conventional water flooding.In addition,high-density brines are effective in decreasing the mobility ratio and facilitating favorable displacement during polymer flooding.However,they can be least effective in alkaline flooding due to the high IFT related to large density differences.Thus,it is suggested to consider the utilization of sustainable high-density brines by taking into account effective factors in petroleum engineering aspects such as stimulation,secondary recovery and polymer flooding.

A Retrospective Study of the Treatment Results &Patterns of Failure of Type II Endometrial Cancer Patients Treated at Radiotherapy Department, NCI, Cairo University during the Period from January 2000 till December 2012

Aim of the study: To identify all clinico-pathological data, different treatment modalities and the different prognostic factors which affected the locoregional control (LC), disease-free survival (DFS), and overall survival (OS) of Type II endometrial cancer patients. Patients and methods: Data of Type II endometrial carcinoma patients who presented to the Radiation Oncology department, National Cancer Institute, Cairo University during the period from (2000-2012) were retrospectively reviewed. Results: Multivariate analysis identified stage as an independent prognostic factor for OS & DFS, and age was an independent prognostic factor for DFS and LC. Low pretreatment hemoglobin levels significantly affected OS. Conclusion: Large and multicentric clinical trials are required to further study this group of patients and define optimum treatment modalities.

Efficacy of Single Burr Hole in Management of Chronic Subdural Hematoma

Background: Surgery of chronic subdural hematoma (CSDH) is a common practice of neurosurgeons. CSDH is considered a pathology of the elderly and usually many co-morbidities are present. CSDH carries high risk of mortality if not treated or not treated well. So, the minimal, safe and adequate surgical intervention is the bases to choose specific surgical maneuver. Aim of the Study: The efficacy of a single burr in evacuation and treatment of chronic subdural hematoma. Methods: This study was held in Assiut university hospitals, neurosurgical department. It is a prospective randomized controlled study. 113 patients were enrolled in this study in the period between March 2018 and June 2019. We included all cases of chronic subdural hematoma (CSDH) and subacute subdural hematoma that were evacuated with single burr hole. Hematomas either, unilateral or bilateral were included. Septated hematomas were excluded. Patients’ clinical characteristics as age, sex, clinical presentation, co-morbidities and patients outcome were recorded. Postoperative status as regards improvement of the neurological status, complications and recurrence of hematoma were recorded. Results: We had 113 patients operated via properly situated single burr hole in our study. 113 patients were included in this study, 79 males (69.9%) and 34 females (30.1%). Age of the patients ranges between 27 years old and 90 years old. Postoperative follow up was evaluated according to Glasgow outcome score (GOS). We had 98 patients with good recovery, 4 patients with moderate disability, 6 patients with severe disability and 5 patients died. Complications were in form of 3 patients with residual hematoma, 2 patients with tension pneumocephalus, 7 patients developed postoperative seizure, 5 cases developed cortical/parenchymal hematoma and 9 cases developed hematoma recurrence. Conclusion: Single, properly situated burr hole with previously described characters is an effective treatment option in cases of CSDH. It helps adequate, effective and safe removal of the pathology with limited maneuver.

Management of Spontaneous Superficial Intracerebral Hematomas

Background: Treatment of primary spontaneous superficial intracerebral hemorrhage (SSICH) is still controversial. The aim of this study is to investigate the effectiveness of craniotomy and early hematoma evacuation vs conservative (non operative) management in patients with SSICH. Methods: A prospective study of craniotomy and early hematoma removal vs. medical management was performed in 20 patients with cortical and subcortical (superficial) primary SSICH admitted to Assiut university hospital in one year period (March 2016-March 2017). Surgical or medical treatment was initiated immediately when patients admitted to hospital. We divided the patients into two groups according to type of treatment. Results: Age of the patients ranged from 2 months to 73 years (mean: 45.84 ± 23.28 years) among the 20 patients studied;13 (65%) were males and 7 (35%) were females. Glasgow coma scale (GCS) at admission was less than 8 in 25%, between 8 - 12 in 45% and 15 in 30% of the patients. Arterial hypertension was the most common associated medical disease (65%). Eleven of patients (55%) had ventricular extension. GCS at admission was the strongest factor affecting outcomes and determined the type of treatment. All patients with a GCS ≤ 8 (5 cases (25%) were died regardless the type of treatment and there was no significant statistical difference in this group in relation to type of treatment p-value (0.606). We had 6 cases (30%) with a GCS 15;all of them were treated conservatively and all of them survived with significant p-value (0.003). Nine patients (45%) had GCS 8 - 12;two of them were treated conservatively and died while the remaining seven patients were treated surgically;five of them survived with significant p-value (0.025). No significant statistical difference was found in the outcome between the surgical and the conservative group regarding having associated intracranial hemorrhage. Conclusions: After analyzing the results, we found that when the GCS is “8 - 12”, surgical intervention is recommended and carried a better prognosis than waiting for the conservative treatment. When GCS is higher “>12”, conservative treatment can be the favorable option. Otherwise, we found no statistical difference between surgical and conservative treatment in the treatment of ICH.

Evaluation of Neuronavigation in Glioma Surgery

Background: Glioma is one of the most common intracranial tumors, the treatment for which is surgical resection. Cerebral gliomas in eloquent brain areas are closely associated with important structures. The deep location of such gliomas renders complete resection difficult overlaying structures can be injured, causing hemiplegia, aphasia, coma, and other severe complications. The degree of resection directly influences the prognosis of patients. The application of neuronavigation enables the accurate localization of lesions during surgery, significantly improving microneurosurgery. The accuracy of navigation, however, has typically been compromised by several factors, including operation error, shifting of registration system, and intraoperative brain tissue deformation (brain shift). Aim of Study: The aim of the study is to evaluate and demonstrate the efficacy of neuronavigation in the management of brain gliomas. Patients and Methods: This is a prospective randomized clinical trial study included 35 patients with brain glioma were operated for excision or biopsy taken. Results: Localization of burr hole and craniotomy flap was excellent in 33 patients (94.2%) and fault in 2 cases (5.7%), 29 patients (82.8%) had near total excision of the lesions, and 6 patients (17.1%) had burr hole biopsy, intra operative course was smooth in 33 patients (94.2%) with no intra operative complications, 2 cases (5.7%) developed intra operative bleeding that was due to liver problems. Reading the post operative imaging shows that 27 patients (77.1%) had mild to moderate post operative edema around the site of the lesion, the other eight cases were free of hemorrhage, infarction or edema. Conclusion: We found that neuronavigation is very helpful in our cases in localization of the lesions, decreasing time of surgery, reducing morbidity and mortality and decreasing hospital stay. There are concerns about navigation systems including time consuming, calculation and registration, restriction of space and view inside the operating field, and so on, we didn’t find these issues as obstacles in our work, but we found that there are many advantages that can be helpful in the process of operation.

Postoperative Use of Dopamine Agonist in Controlling the Residual Mass in Non Functioning Pituitary Adenoma

Background: Non-functioning pituitary adenoma (NFPA) is a challenging tumor. It is usually reached to a large size before it is clinically manifested. Operative interference is the first option in treatment of large NFPA causing compressive manifestations but with frequent postoperative residual masses that is usually required additional treatment. Postoperative radiotherapy carried frequent side effects which open the door for postoperative medical treatment with dopamine agonist (DA) drugs based on the fact that these tumors have a variable amount of dopamine receptors. Lack of randomized, placebo-controlled trials prevents any conclusion on the efficacy of this drug. Its role in controlling postoperative proliferation and decreasing the rate of recurrence of NFPA is still questionable. Objective: Efficacy of bromocriptine (dopamine agonist (DA) drug) in reducing or preventing the re-growth of non-functioning pituitary adenoma NFPA after surgery. Methods: In this study, we examined the outcome of treating NFPA after surgery, with bromocriptine (dopamine agonists drug). This study was a retrospective review of consecutive patients that were treated by the authors at Assiut University Hospital between 2012-2018. All patients had postoperative Bromocriptine in a dose of 2.5 mg twice daily. Results: Thirty two patients were included in this study after they had surgery for NFPA. All patients had a residual mass documented by the immediate post operative MRI. After 6 months of postoperative bromocriptine treatment, and with comparing to immediate post operative images, eleven patients (34%) had mass reduction, thirteen patients (41%) of their residual masses remained unchanged and eight patients (25%) of the mass showed slight increase in size but not required re-surgery. After two years and throughout the follow up period, seven patients (22%) (all were males) had complete disappearance of the mass;ten patients (31%) had more reduction of the size of the mass (two of them were males) and four patients (13%) of the mass remained unchanged (none of them were males) and eleven patients (34%) had increase of the mass and they required re-surgery (two of them were males). Conclusion: Bromocriptine (DA drug) can play a role in reducing the size or preventing the re-growth of non-functioning pituitary adenoma after surgical debulking. Males showed noticeable response comparing to females. Its regular use might limit the need for surgery in this type of tumor. Further studies with large number of patients are highly recommended.

Intelligent Dynamic Inversion Controller Design for Ball and Beam System

The Ball and beam system(BBS)is an attractive laboratory experimental tool because of its inherent nonlinear and open-loop unstable properties.Designing an effective ball and beam system controller is a real challenge for researchers and engineers.In this paper,the control design technique is investigated by using Intelligent Dynamic Inversion(IDI)method for this nonlinear and unstable system.The proposed control law is an enhanced version of conventional Dynamic Inversion control incorporating an intelligent control element in it.The Moore-PenroseGeneralized Inverse(MPGI)is used to invert the prescribed constraint dynamics to realize the baseline control law.A sliding mode-based intelligent control element is further augmented with the baseline control to enhance the robustness against uncertainties,nonlinearities,and external disturbances.The semi-global asymptotic stability of IDI control is guaranteed in the sense of Lyapunov.Numerical simulations and laboratory experiments are carried out on this ball and beam physical system to analyze the effectiveness of the controller.In addition to that,comparative analysis of RGDI control with classical Linear Quadratic Regulator and Fractional Order Controller are also presented on the experimental test bench.

Control of Linear Servo Carts with Integral-Based Disturbance Rejection

This paper describes a system designed for linear servo cart systems that employs an integral-based Linear Active Disturbance Rejection Control(ILADRC)scheme to detect and respond to disturbances.The upgrade in this control technique provides extensive immunity to uncertainties,attenuation,internal disturbances,and external sources of noise.The fundamental technology base of LADRC is Extended State Observer(ESO).LADRC,when combined with Integral action,becomes a hybrid control technique,namely ILADRC.Setpoint tracking is based on Bode’s Ideal Transfer Function(BITF)in this proposed ILADRC technique.This proves to be a very robust and appropriate pole placement scheme.The proposed LSC system has experimented with the hybrid ILADRC technique plotted the results.From the results,it is evident that the proposed ILADRC scheme enhances the robustness of the LSC system with remarkable disturbance rejection.Furthermore,the results of a linear quadratic regulator(LQR)and ILADRC schemes are comparatively analyzed.This analysis deduced the improved performance of ILADRC over the LQR control scheme.

Dosimetric study comparing intensity modulated and conformal pelvic radiotherapy boost plans in locally advanced cancer cervix in NCI-Cairo

Objective:This study was to compare 5 field conformal technique to the intensity modulated radiotherapy (IMRT) 8 fields technique in boosting locally advanced cancer cervix cases after external beam radiotherapy with respect to target volume coverage and dose to normal tissues. Methods:We conducted a single institutional comparative dosimetric analysis of 10 patients with cancer cervix who was presented to radiotherapy department in National Cancer Institute, Cairo in period between June 2012 to September 2012 and received a CRT boost in the place of planned brachytherapy after large field pelvic radiotherapy (PRT) with concurrent chemotherapy were retrospectively identified. All tumors were situated in the low central pelvis. Two plans were done for every patient; one using the 8 fields IMRT and the second one using 5 fields' 3DCRT the two techniques were then compared using dose volume histogram (DVH) analysis for the PTV, bladder, rectum and both femoral heads. Results:Comparing different DVHs, it was found that the planning target volume (PTV) was adequately covered in both plans while it was demonstrates that the 8 fields IMRT technique carried less doses reaching OARs (rectum, bladder, both femoral heads). Conclusion:From the present study, it is concluded that IMRT technique spared more efficiently OARs than CRT technique but both techniques covered the PTV adequately so whenever possible IMRT technique should be used.

Dosimetric study comparing photon and electron beams for boosting the tumor bed in early-stage breast cancer

Objective： The aim of our study was to assess and compare the potential dosimetric advantages and drawbacks of photon beams and electron beams as a boost for the tumor bed in superficial and deep seated early-stage breast cancer. Methods： We planned CTs of 10 women with early breast cancer underwent breast conservative surgery were selected. Tumor bed was defined as superficial and deep with a cut of point 4 cm, those with less than 4 cm were defined as superficial tumors representing 4 patients and those with depth of 4 cm or more were classified as deep tumors representing 6 patients. The clinical target volume （C＇I＇V） was defined as the area of architectural .distortion surrounded by surgical clips. The plan- ning target volume （PTV） was the C＇I＇V plus margin 1 cm. A dose of 10 Gy.in 2 Gy fractions was given concurrently at the last week of treatment. Organs at risk （OARs） were heart, lungs, contra-lateral breast and a 5 mm thick skin segment of the breast surface. Dose volume histograms were defined to quantify the quality of concurrent treatment plans assessing target coverage and sparing OARs. The following treatment techniques were assessed： photon beam with 3D-conformal technique and a single electron beam. Results： For superficial tumors better coverage for CTV and P＇I＇V with good homogeneity with better CI was found for the 3D conformal radiotherapy （3DCRT） but with no significant planning objectives over electron beam. For deep tumors, the 3DCRT met the planning objectives for C＇I＇V, PTV with better coverage and fewer hot spots with better homogeneity and CI. For superficial tumors, OARs were spared by both techniques with better sparing for the electron beam where as for deep tumors also OARs were well spared by both techniques. Conclusion： Boosting the tumor bed in early- stage breast cancer with optimized photon may be preferred to electron beam for both superficial and deep tumors. The OARs dose sparing effect may allow for a potential long-term toxicity risk reduction and better cosmesis.

A comparative dosimetric study of 3-dimensional conformal radical radiotherapy for bladder cancer patients versus conventional 2-dimensional radical radiotherapy in NCI-Cairo, Egypt

Objective: This study was to compare this multiple-field conformal technique to the 2-dimensional (2D) conventional technique with respect to target volume coverage and dose to normal tissues. Methods: We conducted a single institutional prospective comparative dosimetric analysis of 15 patients who received radical radiation therapy for bladder cancer presented to Radiotherapy Department in National Cancer Institute, Cairo (Egypt), in period between November 2011 to July 2012 using 3-dimensional (3D) conformal radiotherapy technique for each patient, a second 2D conventional radiotherapy treatment plan was done, the two techniques were then compared using dose volume histogram (DVH) analysis. Results: Comparing different DVHs, it was found that the planning target volume (PTV) was adequately covered in both (3D & 2D) plans while it was demonstrated that this multiple field conformal technique produced superior distribution compared to 2D technique, with considerable sparing of rectum and to lesser extent for the head of both femora. Conclusion: From the present study, it is recommended to use 3D planning for cases of bladder cancer especially in elderly patients as it produces good coverage of the target volume as well as good sparing of the surrounding critical organs.

Impact of Postoperative Radiotherapy and Chemotherapy on Survival for Patients with Node Positive Oral Cancer

Purpose: The aim of the present study is to compare between the use of post-operative concurrent chemotherapy and radiotherapy alone on survival for patients with high risk oral cavity tumors at the National cancer Institute of Egypt, undergoing surgery and receiving adjuvant treatment. Patients and Methods: This is a retrospective study, which was carried out at the National Cancer Institute (Cairo University) on patients with node positive oral cavity cancer diagnosed between the year 2000 and 2008. The study included 60 patients (45 males and 15 females) with median age 57 years old. The patients underwent surgery, followed by postoperative radiotherapy 60 Gy/6 weeks versus postoperative radiotherapy 60 Gy/6 weeks with concurrent cisplatin 100 mg/m2 at day 1, day 22 and day 43. Results: Regarding use of concurrent chemotherapy, there was a significant difference in overall survival rate and locoregional control favoring patients who received concurrent chemotherapy and radiotherapy, 3 years and 5 years overall survival rates respectively were 53.8% and 40.4% compared to 37.5% and 26.3% for patients who didn’t receive any chemotherapy with (p 0.038) for 5 years. Regarding age, there was a significant difference in overall survival rate favoring patients ≤57 years in both arm groups, 3 years and 5 years overall survival rates respectively were 51.6% and 38.9% compared to 28.3% and 18.9% for patients >57 years with (p 0.028) for 5 years. Conclusion: We recommend for oral cavity tumor patients at the NCI of Egypt who have positive neck nodes to be treated with concurrent chemo-radiotherapy rather than radiotherapy alone especially by using the new techniques as intensity modulated radiotherapy (IMRT) and image guided radiotherapy (IGRT).

Fertility preservation after surgical transposition of the ovaries for pelvic tumors

Objective: The aim of the study was to assess the hormonal profile level in females with pelvic tumors after surgical transposition of the ovaries during surgery followed by postoperative radiotherapy to the pelvis. Methods: Fifteen patients with rectal, bladder and cervical cancer were included in the study with their age ranged between 25 and 40 years old, 7 patients with cancer rectum, 3 patients with bladder cancer and 5 had cancer cervix. Ovarian transposition was done for patients during surgery followed by external beam radiotherapy to the pelvis, hormonal assessment was done for the patients before and after exposure to radiation. Results: No intra-operative or post-operative morbidity was observed in patients treated by laparotomy. Patients were found to have regular menstrual cycles. Their FSH, LH and progesterone levels were within normal ranges. Conclusion: Proper transposition of ovaries during laparotomy away from the radiation field can preserve the ovarian function in patients with pelvic tumors.

A comparative dosimetric study of neoadjuvant 3D conformal radiotherapy for operable rectal cancer patients versus conventional 2D radiotherapy in NCI-Cairo

Objective:This study was to compare this multiple-field conformal technique to the AP-PA technique with respect to target volume coverage and dose to normal tissues.Methods:We conducted a single institutional prospective comparative dosimetric analysis of 22 patients who received neoadjuvant radiation therapy for rectal cancer presented to radiotherapy department in National Cancer Institute,Cairo in period between June 2010 to September 2011 using 3D conformal radiotherapy technique for each patient,a second radiotherapy treatment plan was done using an anteroposterior (AP-PA) fields,the two techniques were then compared using dose volume histogram (DVH) analysis.Results:Comparing different DVHs,it was found that the planning target volume (PTV) was adequately covered in both (3D & 2D) plans while it was demonstrates that this multiple field conformal technique produces superior distribution compared to 2D technique,with considerable sparing of bladder,ovaries and head of both femora.Conclusion:From the present study,it shows that it is recommended to use 3D planning for preoperative cases of cancer rectum so far it produces good coverage of the target as well as good sparing of the surrounding critical organs.

The Use of Intensity Modulated Radiotherapy as a Mean of Reducing Dose to Bone Marrow for Patients with Cancer Cervix Treated at Nci, Cairo, Egypt. Dosimetric Study

Purpose: To test the use of Intensity Modulated Radiotherapy (IMRT) to spare the bone marrow (BM) in patients treated with cancer cervix through using the bone marrow an organ at risk. Patients and methods: Thirteen patients with stage (IB2-IIIB) intact cervix cancer were included;C-T simulation was done with contrast and full bladder with slice thickness 2.5 mm. Clinical Target Volume (CTV) included the cervix, uterus, upper half of the vagina, parametrium and regional lymph nodes. The CTV was expanded by 1 cm to form the Planning Target Volume (PTV). The organ at risk (OAR) included the bladder and rectum, the external contour of the pelvic bones to define the Pelvic Bone Marrow (PBM). Four plans were done for every patient with anteroposterior-posteroanterior (AP/PA), three dimensional conformal radiotherapy (3DCRT), IMRT, bone marrow-sparing intensity-modulated pelvic radiotherapy (BMS-IMRT). Results: BMS-IMRT reduced the V20, V30, V40 and V45 of the BM in comparison to 3DCRT and IMRT plans. Reduction in V20 with BMS-IMRT plan compared to 3DCRT (p 0.03). The PBM volume receiving 5, 10 and 20 Gy was lower AP/PA than BMS-IMRT (p < 0.01, p 0.001 and p 0.04 respectively). The volumes of the rectum and bladder receiving dose of 40 and 45 Gy were lower in BMS-IMRT plan compared to AP/PA and 3DCRT plans with p = 0.01 for both of them. PTV cover was better in the BMS-IMRT and IMRT plans. Conclusion: BMS-IMRT decreased the irradiated BM volume compared to other techniques. Thus using BMS-IMRT is recommended to decrease hematological toxicity and avoid treatment interruption.

Acousto-optical modulation of thin film lithium niobate waveguide devices

Due to its strong piezoelectric effect and photo-elastic property, lithium niobate is widely used for acousto-optical applications. However, conventional bulk lithium niobate waveguide devices exhibit a large footprint and limited light–sound interaction resulting from the weak guiding of light. Here, we report the first acousto-optical modulators with surface acoustic wave generation, phononic cavity, and low-loss photonic waveguide devices monolithically integrated on a 500 nm thick film of lithium niobate on an insulator. Modulation efficiency was optimized by properly arranging the propagation directions of surface acoustic waves and optical guided modes.The effective photo-elastic coefficient extracted by comparing the first and third harmonic modulation signals from an on-chip Mach–Zehnder interferometer indicates the excellent acousto-optical properties of lithium niobate are preserved in the thin film implementation. Such material property finding is of crucial importance in designing various types of acousto-optical devices. Much stronger amplitude modulation was achieved in a high Q(>300,000) optical resonator due to the higher optical sensitivity. Our results pave the path for developing novel acousto-optical devices using thin film lithium niobate.

Carbonate rocks resistivity determination using dual and triple porosity conductivity models

The rocks may be classified as Archie rocks or Non-Archie rocks,depending on the link between pore structure and resistivity of the rock.For carbonate rocks,keeping this factor in view,the applicability of Archie's law tends to be unreasonable and employing Archie's equation will ultimately lead to inaccurate estimates of the water saturation.Numerous investigators have reported models that forms a link between laboratory results and field well logs to determine water saturation in intricate pore systems.In case of complex systems,Archie's law fails to correctly define the resistivity-index curves.In addition,it is imperative to carry out investigations at lower saturation values in order to elaborate the non-Archie characteristics.This brings the dual and triple porosity conductivity models into the equation.As these models are essential in defining the considerable changes of the resistivity-index curves,both qualitatively and quantitatively.The linkage between the two models is depicted electrically in series or in parallel.Moreover,it is possible to have a combination of the two configurations.As a result,the experimental results can be modeled accurately using least parameters.This work presents two models to determine water saturation in carbonate rocks,containing dual and triple porosity systems.This study also investigates the impact of different influential parameters such as saturation exponents,conductivity ratios,and pore volume fraction of each network systems,on the new models.Finally,the effect of each parameter is individually studied and the sensitivity analysis on the RI curves is produced.A new approach to apply these models is also explained which requires the use of NMR log,mercury injection capillary pressure(MICP)measurement,and simple plotting techniques to determine the water saturation.The proposed new models help petrophysicists to estimate water saturation in Non-Archie rocks,containing double and triple porosity network systems.

New insights into porosity determination using artificial intelligence techniques for carbonate reservoirs

The porosity of the petroleum reservoirs is considered one of the most important parameters in reserve estimation because it determines the effective volume of the hydrocarbon that is stored in the reservoir.Based on the reserve estimation,the development plan can be set and managed.Porosity can be determined in the laboratory which is the most expensive methods.Porosity also can be determined from the logs such as density,neutron,sonic,and NMR logs.There are a lot of uncertainties in the porosity estimation from wireline logs because it depends on many statistical analysis and also is affected by the logging environment and logging tools.The prediction of the porosity from different porosity logs using artificial intelligence(AI)methods validated with the laboratory measured values is the best method to determine an accurate value of the rock porosity.The objective of this research is to evaluate AI tools such as artificial neural network(ANN),Support vector machine(SVM)and Adaptive neuro fuzzy inference system(ANFIS)to predict the reservoir porosity based on wireline log data.More than 1700 field measurements of porosity with logs data were used for training and testing the AI techniques.The results obtained showed that ANN and ANFIS can be used to estimate the reservoir porosity based on log data with a high correlation coefficient(R)and low average absolute percentage error(AAPE).The main inputs required for porosity estimation are bulk density,neutron porosity,and sonic compressional time.The developed mathematical equation based on the weights and bias of the ANN model can be used to predict the reservoir porosity based on log data with a correlation coefficient of 0.98 and an AAPE less than 8%.The advantage of this work is that we extracted the mathematical model from the ANN that can be used directly to determine the porosity without the need for training and testing the data.The porosity estimation from the neutron-density crossplots,which is the current technique used by the industry,yielded 14.7%error.

Development of new correlations for the oil formation volume factor in oil reservoirs using artificial intelligent white box technique

Oil formation volume factor(OFVF)is considered one of the main parameters required to characterize the crude oil.OFVF is needed in reservoir simulation and prediction of the oil reservoir performance.Existing correlations apply for specific oils and cannot be extended to other oil types.In addition,big errors were obtained when we applied existing correlations to predict the OFVF.There is a massive need to have a global OFVF correlation that can be used for different oils with less error.The objective of this paper is to develop a new empirical correlation for oil formation volume factor(OFVF)prediction using artificial intelligent techniques(AI)such as;artificial neural network(ANN),adaptive neuro-fuzzy inference system(ANFIS),and support vector machine(SVM).For the first time we changed the ANN model to a white box by extracting the weights and the biases from AI models and form a new empirical equation for OFVF prediction.In this paper we present a new empirical correlation extracted from ANN based on 760 experimental data points for different oils with different compositions.The results obtained showed that the ANN model yielded the highest correlation coefficient(0.997)and lowest average absolute error(less than 1%)for OFVF prediction as a function of the specific gravity of gas,the dissolved gas to oil ratio,the oil specific gravity,and the temperature of the reservoir compared with ANFIS and SVM.The developed empirical equation from the ANN model outperformed the previous empirical correlations and AI models for OFVF prediction.It can be used to predict the OFVF with a high accuracy.

Impact of methane adsorption on tight rock permeability measurements using pulse-decay

The permeability of the rock is usually measured by the injection of gas using Darcy's flow model(pulse-decay).For oil formations,helium and nitrogen are the most common gases used to measure the permeability of the rock.However,recent approaches are based on the use of methane as it minimizes the properties difference between the testing fluid and reservoir fluid.This work focused on the latter approach to compute the correction of gas adsorption.The most widely used model is Cui et al.model that is based on Langmuir adsorption isotherm.In this work,we introduced a modified model that is based on Freundlich isotherm.This model also includes the correction for gas adsorption such as Freundlich isotherms proved to be more appropriate for the adsorption on intact reservoir rock.The model is based on gas and rock properties and reduced pressure and temperature were used to accommodate the gas compressibility.The modified model can also capture effective porosity of adsorption(a)that can correct the pulse-decay storage capacity parameters a and b.The permeability estimation of ultra-tight samples using the modified approach is enhanced owing to the correction in the storage volume and rock porosity.Including the proper adsorption isotherm enhanced the porosity estimation because Langmuir isotherm yielded 11%porosity and Freundlich isotherm yielded 12%porosity.Similar results were obtained in the permeability estimation,Langmuir isotherm resulted in a 1.5%error compared to zero error in the Freundlich isotherm estimation.