Artificial Neural Network Modeling Enhancing Shear Wave Transit Time Prediction

Sonic log is the most versatile reservoir evaluation tool that has been introduced to the industry. Compaction,erosion and over pressurized zone can be evaluated by sonic log.Also primary porosity can be determined from compressional sonic wave transit time and secondary porosity will be calculated by comparing sonic derived porosity log with neutron and density based porosity log.On the other hand all of the rock mechanical properties can be evaluated using simultaneous use of compressional and shear sonic wave transit time.It is essential to have

Review of Numerous Approaches for Unconfined Rock Compressive Strength Estimation

Most problems faced by practicing of the wellbore stability analysis involve evaluation of rock mechanical properties especially unconfined compressive strength(UCS) of formations,which is one of the major inputs for stability analysis models of the borehole.Different sources can be used to develop rock strength profile along the wellbore which is very essential to plan the mud weight window or bit selection for drilling operation.Using this

Investigation of trend between porosity and drilling parameters in one of the Iranian undeveloped major gas fields

Porosity is one of the main parameters that should be considered when a gas or an oil field is assessed.Hence,the availability of porosity is crucial in any rock and formation analysis.However,this parameter is not always available and direct measurement is scarce and usually is confined to appraisal phase of a field.Therefore,in this study it is aimed to find a relationship in order to estimate porosity in afterward phases.The data of 5 appraisal wells of an undeveloped gas field has been gathered to perform this purpose.The full set wireline logging data and drilling data were available.The data inherit high level of fluctuation which is normal with respect to real direct measured data.The smoothed curving was utilized and as a result,the fluctuation was diminished considerably and the feasibility of carrying out the investigation was being established,accordingly.To normalize and gather drilling data in a parameter in order to have a better view and investigation,sigmalog method was employed.It was observed that there is a clear exponential relationship between porosity and drilling data and curve fitting was utilized to conduct a numerical relationship.The curve fitting was established with R^(2)=0.83 and a trustworthy fitting resulted.The results demonstrate the possibility of porosity estimation by using drilling data.Furthermore,a numerical relationship is given for a specific field.The porosity estimation can lead to better analysis of newly drilled rocks and formations leading to more efficient field development strategies.

Shale hydration inhibition characteristics and mechanism of a new amine-based additive in water-based drilling fluids

In this work,shale hydration Inhibition performance of tallow amine ethoxylate as a shale stabilizer in water based drilling fluid,was investigated through these tests:bentonite hydration inhibition test,bentonite sedimentation test,drill cutting recovery test,dynamic linear swelling test,wettability test,isothermal water adsorption test,and zeta potential test.The results showed that bentonite particles are not capable of being hydrated or dispersed in the mediums containing tallow amine ethoxylate;tallow amine ethoxylate had shown a comparable and competitive inhibition performance with potassium chloride as a common shale stabilizer in drilling industry.Some amine functional groups exist in tallow amine ethoxylate structure which are capable of forming hydrogen bonding with surfaces of bentonite particles.This phenomenon decreased the water adsorption on bentonite particles'surfaces which results in reduction of swelling.Tallow amine ethoxylate is also compatible with other common drilling fluid additives.

Investigation of production depletion rate effect on the ne ar-wellbore stresses in the two Iranian southwest oilfields|

Effect of depletion rate on wellbore stability due to production of oil from hydrocarbon-bearing reser-voirs is important and can result in a reduction of the reservoir pore pressure.A reduction in the reservoir pressure,in tum,results in a change in the stresses acting within the reservoir.If these changes are not well analyzed and applied in future calculations,we may be unsuccessful in some cases such as drilling infill wells or extended wells,forecast of sand production and optimum flow rate,preventing of casing collapse,etc.Therefore,knowing the stresses around the well at every stage of production is fundamental to the next calculations.In this paper,we recognized these changes in near-wellbore stresses using data from logging(image log,dipole sonic,full set log,mud log),production data,infor-mation from kick,blow out,loss etc.and determined it using Techlog software and theoretical calcu-lations.Three wells of two huge oilfields of sw Iran were investigated after depletion or production for long years.In each well,state of stresses were calculated in cases of safe drilling mud weight using log data and theoretical equations.At the end effect of depletion rate on wellbore stability was investigated in these three wells.

Kinetic modeling of cement slurry synthesized with Henna extract in oil well acidizing treatments

Acidizing treatment in petroleum reservoirs is a short-term and viable strategy to preserve the productivity of a well.There is a major concern for the degradation of cement sheath integrity,leading to poor zonal isolation and environmental issues.Therefore,it is essential to understand how the cement behaves when attacked by hydrochloric acid.In this study,a cement slurry by incorporation of the Henna extract,as an environmentally friendly cement additive,was synthesized as a potential solution to solve this problem.The characteristics of the treated cement slurry were compared with a reference slurry(w/c?0.44)which is composed of only cement and water.A kinetic study was carried out to evaluate the adsorption behavior of the cement slurries exposed to an acid solution with 0.1 M HCl in a range of 25 to 55C conditions.The features of the cement slurries were evaluated by multiple analytical techniques such as XRD,FTIR,TG,and DSC analysis.From the experimental data,it is concluded that the second-order Lagergren kinetic model revealed to be the best in describing kinetic isotherms taken,because the margin between experimental and calculated values was minor for this model.The results of the characterization and HCl interaction kinetic studies underlined the prominent protective role of Henna extract-modified cement slurry in the enhancement of the cement resistance against acid attack and utilization in environmentally favorable oil well acidizing treatments.

Experimental investigation of the application of Eucalyptus bark to prevent lost circulation in pay zones with acid dissolution capability

Loss of drilling fluid is a common problem during the drilling of wells and it restricts the appropriate functionality of muds.Drilling fluid loss significantly increases drilling costs and non-productive time as well as the drilling operation risks.Various investigations have been carried out in order to find appropriate mud additives that either block fractures and pores or reduce fluid loss by improving the fluid rheology.Cheap,environmentally friendly and effective additives are still required by the drilling industry.Hence,the application of available materials in each region,to produce appropriate additives,is a challenge for the oil industry.In this study,Eucalyptus Camaldulensis(EUC)bark powder has been chosen as a new,fibrous,cheap,environmentally friendly and available material to control fluid loss,particularly in southern Iran.Different characterization tests,such as acid dissolution and fluid loss control,were carried out to study the performance of the new proposed additive.Removal by hydrochloric acid and sulfuric acid were studied at various acid concentrations and temperatures.Dynamic fluid loss was also measured at different EUC concentrations.Our study showed that EUC powder can reduce the final fluid loss by 88-97%,the initial fluid loss by 45-66%,and the total loss by 87e94%,which is a satisfactory level.