bluuebunny/crossref_metadata_2025_split huggingface dataset:
A Case Study on Optimization of PCP Operations for Production Increase in an Unconsolidated Sandstone Reservoir
Authors: Netzhanova Akmaral , Bae Wisup , Arystanbay Rustem 
Published: July 2015

Abstract
The ZH field located in Kazakhstan is comprised of shallow, unconsolidated sandstone reservoir that is being produced medium sandy oil by the help of progressive cavity pumps (PCP). The nature of unconsolidated reservoir makes overall production inefficient; due to sand production being a major concern in the field. High frequency of workover operations and limited productivity of wells were caused by sand production. Moreover, pump seizure happens more often because of the low fluid velocity, there is sand inside the production wells can not move up to the surface.
The goal of this study is to increase oil production by optimizing the progressive cavity pumps operation. Improving production requires minimizing workover frequency, therefore sand should be lifted out of the well continuously with the fluid. This can be achieved by controlling the ratio of the actual fluid velocity to the sand settling velocity. The fluid velocity in the tubing should be enough to lift most of the produced sand particles from the bottomhole of a well.
The statistics showed that production wells with fluid velocities of 75% of sand settling velocity or less were likely to have pump seizure with the lack of sand carrying capacity in the tubing. By increasing pump size, modifying tubing size, and increasing pump rotation per minute (RPM), PCP performance was significantly improved. This paper shows the significance of the parameters stated above.
Field cases in PCP optimization are summarized. The successful cases highlight an incremental oil production of 126 m3/d with seldom workover. Unsuccessful cases were characterized by often and sudden pump seizures with increased watercut. This study has shown that maintaining production rate through PCP operation coupled with continuous sand lifting is more beneficial than controlling the sand production such as installing gravel packs.
Vertical Reservoir Connectivity Evaluation in Dunga Field, Albian Horizon
Authors: Zhumekeshov A. , Elbattawy A. 
Published: July 2015

Abstract
All Dunga field wells to date have been producing from a low permeability sandstone reservoir of Aptian age. However, while drilling an exploration well, formation evaluation revealed the existence of hydrocarbons in a shallower horizon (Albian) which was not known to be hydrocarbon bearing in the Dunga area. This raised a need to further appraise the accumulation and reduce geological uncertainties.
In this paper we discuss the unique properties and uncertainties that will affect future development of the Albian reservoir, and present results from a detailed wireline logging program, fluids pressure-volume-temperature properties, and extended well testing results to evaluate the hydrocarbon find in order to reduce those uncertainties.
Conventional interpretation of petrophysical logs was complemented by wireline formation testing (WFT) pressure data and formation fluid samples. The laboratory analysis of hydrocarbon samples is compared to real time downhole optical analysis of formation fluids.
Additionally, pressure transient analysis (PTA) from WFT was compared to conventional PTA results from DST completed well testing, in order to help understand the vertical permeability profile.
We also propose additional future work to complement the work presented in this paper by suggesting a vertical interference test and well-to-well data evaluation.
All these studies will help to answer key decisions on developing an Albian reservoir which has no analog in this region.
Scaling Gravity-Drainage Oil Recovery from Fractured Reservoirs Using 3D Discrete Fracture Models
Authors: Hui Mun-Hong (Robin) , Heidary-Fyrozjaee Mohsen , Kamath Jairam 
Published: July 2015

Abstract
Gravity drainage caused by density difference between fluids in the fractures and in the matrix rock can be an effective mechanism for recovering oil from naturally fractured reservoirs (NFRs). This process has been studied in the past, and oil-recovery-rate scaling laws that depend inversely on matrix block height have been developed.
In this work, we show that these scaling laws are only valid for one-dimensional flow where fracture spacing is small compared to matrix block height. We use single-element mechanistic fracture models and discrete-fracture-matrix (DFM) models of realistic systems to develop new scaling relationships that better capture 3D gravity drainage in weakly wetting realistic NFRs. The single-element models reveal that the gravity drainage rate scales as a function of both fracture spacing and matrix block height, and not only on the inverse of matrix block height as previous investigations suggested. This has implications for maximum gravity-drainage rates that are possible in fractured reservoirs—either through the geological distribution of heterogeneities or through operational control of the fluid-height difference in the fractures and matrix. We also create detailed DFM models for geologically realistic fracture networks that result in a spatially variable distribution of fracture spacing and matrix block height, and describe how to scale gravity drainage in such systems.
Application of Polymer Gellan for Injectivity Profile Leveling
Authors: Gussenov I. Sh. , Ibragimov R. Sh. , Satpayev K. I. , Kudaibergenov S. E. , Satpayev K. I. , Abilkhairov D. T. , Kudaibergenov D. N 
Published: July 2015

Abstract
This work describes the results of laboratory experiments carried out on core samples and sandpack models as well as the field pilot tests conducted in October 2013 on 2 injection wells of Kumkol oilfield. The reduction of the permeability of porous space was achieved by injection of gellan solution, gelation of which is initiated by the following cations: Ba2+, Са2+, Мg2+, K+, Na+, containing in brine water. On the basis of laboratory experiments the suitable concentrations of polymer reagent for the pilot tests were selected. A series of laboratory experiments were carried out to reduce the amount of polymer reagent without detriment to the efficiency of the technology. Also the mixtures of polysaccharides gellan and xanthan in the weight ratios 1:2; 1:1; 2:1 were found to be more effective in comparison with separate components. One of the main features of this work is that polysaccharide gellan was used for the first time in oil industry, thus new application frontier for this polymer was found. The most remarkable feature of the proposed polymer is due to its gelation after contacting with brine water so no additives are needed to initiate the gelation process inside of the oil formation in contrast to polyacrylamide gels crosslinked by chromium ions which are widely used for conformance control operations.
Optimization of Well Hydraulics for Riserless Deepwater Drilling Operations under High Temperature and High Pressure Environment
Authors: Patel Akshit , Chaudhari Ravi , Deendayal Pandit 
Published: July 2015

Abstract
World's energy demand is on upsurge and Oil & Gas industry has been directed towards the exploitation of deepwater oil and gas resources. To make this operation successful petroleum industry is continuously demanding new innovative drilling technology that can be easily implemented. One of the constraints that hinders the deepwater exploration is its continuously shrinking narrow window between pore pressure and fracture pressure that further limits the reliability of old conventional riser drilling technique.
Dual gradient drilling (DGD) is a managed pressure drilling that involves use of two different annular fluids for drilling a prospect providing a favorable annular pressure profile and simpler, safer & economical well design.
In any of the rotary drilling operation, drilling hydraulics is the most complicated and least understood drilling variable as it involves complex relationship between drilling fluid, drill bit and formation. Riserless drilling, one of the type of DGD, eliminates the use of marine riser (u-tube is imbalance) and involves use of an additional subsea mud pump at seabed which, supplements to the complication for hydraulics computation as compared to conventional drilling.
In drilling HPHT deepwater wells, drilling fluid is constantly exposed to its own column pressure and formations geothermal gradient which subsequently affects the mud rheology and density. These altered rheological parameters leads to inadequate hole cleaning and lowers the drilling efficiency. High temperature in the wellbore cause's fluid expansion and high pressure causes fluid compression and these changes get extremely severe as water depth and drilling depth increases. Hence it becomes necessary to consider the HPHT effects on Equivalent Circulating Density (ECD) and to correct & optimize the hydraulic program to ensure the best utilization of the hydraulic energy for effective hole cleaning.
This paper presents a detailed study of Well hydraulics for riserless drilling considering the HPHT effect on Equivalent Circulating Density and its optimization so as to ensure riserless drilling operation is conducted in safe and effective manner. Also the paper is concluded with some recommendations on operational and design strategies.
Tight Sandstone Reservoir Renaissance: Baimiao Gas Condensate Field
Authors: Miao Heping , McBurney Cameron J. , Wu Xinrong , Wei Ruiling , Zhao Yuxin 
Published: July 2015

Abstract
Gas condensate has become very important because the liquid makes it a high-quality hydrocarbon fluid. Tight gas condensate reservoirs may contain large reserves, but can be extremely costly to develop. The Baimiao gas condensate reservoir is a deep, structurally complex, low- permeability play with a high condensate yield.
This kind of tight gas condensate reservoir encounters many challenges in its exploitation, especially well bottom-hole liquid dropout. Many of the producing wells in the Baimiao tight gas field do not naturally produce the liquids that dropout in-situ around the wellbore. Thus, it is imperative that innovative and effective technologies are applied to lift the condensate-collecting bottom-hole, ultimately prolonging the life of the well and improving the reservoir gas recovery. The techniques used include liquid drainage with narrow tubing, a newly designed plunger gas-lift with a skid-mounted gas-lift, and an interstitial gas-lift.
During the last five years, the Baimiao operator team used integrated gas-lift technology and fine operating procedures to produce the gas condensate. The primary objective of this paper is to advance the understanding of multiphase flow production within tight gas condensate reservoirs. To achieve the objective, a series of closed-gas-lift techniques for field application were introduced; the results from the application of the techniques are presented. Field example summaries are presented at the end of the paper.
A New Early Warning Model with Vector Machine for Abnormal Production Prediction
Authors: Li JunJian , Jichen Zhao , Hanqiao Jiang , Wenchao Fang , Hongxia Liu , Wu Xiao 
Published: July 2015

Abstract
Some mature reservoirs in China are encountering a sharp production decline, indicating a near-bleak production stabilizing prospect. Production fluctuation is essentially a phenomenon with a variety of affecting factors. An effective monitoring method has become a must with urgency for high water cut reservoirs. The existing development analyzing method or warning method is merely restricted to some particular indicator regarding development dynamics. However this kind of mechanism cannot be responsibly extended to continental deposited formations with strong heterogeneities for a lack of reliability and accuracy. In a reservoir engineering standpoint, all fluctuation in production can be feasibly traced from corresponding development dynamics indicators, which can change accordingly. Thus it is possible production change might be foreseen or predicted through analyzing the abnormal variations in indicators. We may start up analysis with oilfields and oil production plants owning sharp production variations, probe the causes behind and find the reflective indicators from 47 reservoirs. Our study has come up with a total of 10 perspective indicators for early warning, for instance, previous year oil rate ratio of new wells, ratio of oil rate from production enhancement, production injection ratio, enhancement efficiency and measurement Shortage, and the like. Various comparison and assessment standards are viable for different indicators. Oil production variations are further categorized into abnormal, normal, and better scenarios after evaluating uni-indicator using methods of plan comparison, trend comparison and history comparison without a neglect on individual indicator performance. Based on conventional warning strategies, a fresh early warning model with vector machine is devised. We apply this new model to 12 reservoirs in Shengli oilfield. Over 90% of abnormal production variations are successfully detected by this model through analyzing their nearly 20-year production history, yielding a practically good predicting accuracy and showcasing a big promise in effective monitoring for oil production.
Advances in Numerical Modeling of Downhole Dynamics for Perforated Well Completions
Authors: Bale Derek , Ji Minsuk , Satti Rajani , Gilliat Jim 
Published: July 2015

Abstract
Perforation operations are an important part of the well completion process in many field developments today. However, there are two considerations paramount to such a design. First, the post-job well production rate depends critically on a complex system in which the formation, perforations, and wellbore are dynamically and nonlinearly coupled together. Second, perforating operations can place a large dynamic load on downhole equipment. Predicting the spatial loading and its transient behavior is an important step in a completion design that implements risk mitigation to avoid damaging downhole equipment. In this study, we use a numerical modeling tool that has been used to simulate the dynamic behavior of the wellbore-reservoir system during perforating pre-job design. A typical case for this modeling software generates a quantitative prediction for the transient distribution of pressure, mass, velocity, and energy from the perforating event. These transients are commonly analyzed and incorporated into completion designs.
In this paper, two critical components of modeling relative to perforating job design will be evaluated and characterized. First, the wellbore-perforation-formation coupling will be evaluated and characterized using a modified version of the code designed to model API RP-19B Section IV flow testing. Section IV experimental data will be compared to numerical predictions. We present successful predictions of pressure transients that match experimental data. The second component of the software evaluated and characterized in this paper is the pressure, volume, temperature (PVT) accuracy and its implementation. NIST thermodynamic data, together with shock tube examples with pressure and temperature ranges relevant for deep-water completions will be used. We demonstrate that, although the current PVT implementation is accurate on typical downhole jobs, it could have limitations at higher pressures and temperatures. Finally, we present an improved numerical implementation for the modeling software.
Microannulus and Cement Evaluation: Effectiveness of Cement Evaluation Using Sonic and Ultrasonic Technologies in Wells with Microannulus Between Casing and Cement Sheath
Authors: Timonin Andrey , Lungershausen Dirk , Kravets Petr 
Published: July 2015

Abstract
Detailed cement evaluation with good azimuthal coverage is paramount for many wells in Chinarevskoe field, western Kazakhstan, as it affects perforation placement for acid treatment of thinly layered formation that is very heterogeneous, with varying permeability, reservoir pressure and water saturation. Analysis in these wells is performed not only to evaluate cement quality, but also to relate it to casing centricity with respect to formation or outer casing walls to help reaching objectives for cementing jobs in future wells.
Cement evaluation with wireline tools is one of the primary means for determining whether the objectives of a cementing job have been reached once the job is finished. Several logging techniques are currently available for measuring cement quality, including sonic cement bond logs (CBL) and ultrasonic logs. These logs are affected by a microannulus to various extents, and this can make a big difference in our interpretation of cement placement quality.
The sonic CBL and ultrasonic imaging log were run to evaluate cement quality in wells in Chinarevskoe field. Most of the wells exhibit the presence of a microannulus between the casing and cement sheath that develops just after the cementing job is completed. We observe that sonic CBL logs are affected by the presence of the microannulus. Cement evaluation is further complicated by the presence of contaminated cement where the acoustic impedance of the mud is close to the acoustic impedance of the contaminated cement. In these wells, a new generation cement evaluation service with enhanced ultrasonic measurements was deployed. A comparison of the results with traditional ultrasonic and sonic measurements shows that analysis of the enhanced ultrasonic logs improves cement evaluation in the presence of microannulus.
Normal faulting and role of the reverse drag in analyzing petroleum systems, an example of 2D modeling from the Nam Con Son Basin (Vietnam)
Authors: Spahic Darko , Vanin Valery , Perepelina Anastasia , Aryakbaeva Zhuldyz 
Published: July 2015

Abstract
The studied area is located around a margin of the Nam Con Son Basin (NCSB) (Vietnam). A 2D seismic interpretation data indicated two main structural domains that could influence the hydrocarbon distribution – hanging wall and footwall of the possible large-scale reverse drag. In this study by using Cenozoic petroleum systems modeling around a cluster of normal faults we investigate present day migration paths assessing the role of hanging wall and footwall domains in hydrocarbon exploration. In order to analyze fluid migration, we reconstructed burial history, timing of hydrocarbon generation, migration paths with emphasis on tectonic model further observing the present day hydrocarbon distribution. The complete results of the petroleum system modeling are presented by Spahić et al. (in press) whereby in this paper, we focus on the footwall domain of the main normal fault.
The studied section exhibited finite length faults that are associated with possibly two rifting phases, whereby the role of Master faults was separate to investigate fluid distribution. Faults are root in the basement propagating towards the higher sections. For the modeling, Paleogene Formations accommodated in near-shore and lacustrine environment are adopted as potentially the main source of the fluids. The higher sections are divided into the reservoir and trap systems and are tested for fluid migration using PetroMod 2012.2 (Mark of Schlumberger). Results indicate that main migrations routes could be associated with the main fault further distributing fluid across the investigated section. The two main structural domains, large-scale hanging wall and footwall most probably associated with the reverse drag developed around the main normal fault could be treated as a potential trapping mechanism. The computed migration paths pointed that not only well-known rollover anticlines could be recognized as a potential trap system, but also perspectives of the footwall domain could be further investigated.
Comprehensive Study on the Heterogeneity of Carbonate Reservoirs in Carboniferous at Eastern Area of Pre-Caspian Basin
Authors: Zhiqiang Xu , Shutang Jin , Hongtao Chen , Xin Shi , Jianhui Xue , Hulin Niu , Arkbar Erken Aikebaijiang , Margarita Bryzgalova 
Published: July 2015

Abstract
Carboniferous is one of the main hydrocarbon exploration and production sequence in North Teluwa area at the eastern region of Pre-Caspian basin (Fig.-1). The reservoir rocks in Carboniferous are composed mainly of limestone and dolomite overlaid by Permian pre-salt zone.
Petroleum exploration for carbonate reservoirs in the pre-salt Carboniferous sequences in study area inevitably faces the challenges as (1) pre-drilling, the structure traps' (leads') deformation caused by uneven seismic velocity through the salt zone has been misleading to drill false trap; (2) post-drilling, the heterogeneity of carbonate reservoir performance has been confusing for understanding and appraisal the reservoir.
Pre-stack depth migration of 3D seismic processing method combing with drilling data seems to have satisfied the exploration and development geologists since some appraisal wells completed here.
This study as a pilot testing experiment is mainly concentrated on the reservoir heterogeneity through integrated analyses of core, borehole imaging logging and combining with high resolution seismic technique equipped with Broadband, Wide azimuth and High density (BWH) acquisition and processing measures.
Core analysis reveals the mechanics and types of porosities in these carbonate reservoirs, and BWH information has been used to illustrate changes between wells. The study and analyses results are aimed at to provide reliable models for geologists and geophysicists when they are working on the data processing and interpretation and also might be as referential information for well testing and production engineers working on seismic inversion in reservoir prediction in this area.
A Mechanistic Study of IOR Processes for Naturally Fractured Reservoirs
Authors: Shie-Way Wang , Zhumagulov Kanat , Liu Ning , Villegas Mauricio 
Published: July 2015

Abstract
This study presents a process to investigate mass transfer between fracture and matrix in naturally fractured reservoirs. The study has three parts: (1) the effect of imbibition by capillary pressure Pc in matrix, (2) mass transfer between fracture and matrix through k*σ, and gravity drainage, and (3) combination of capillary pressure, gravity, and viscous forces.
The important results from this study are listed below.
Part-1: The counter current flow theory predicts the capillary pressure between two adjacent cells will have same value at equilibrium condition for both gas-oil and oil-water systems. In addition, the saturation in each cell has a tendency to approach a value where Pc=0 regardless the wettability of the Pc curve.
Part-2: Simulation shows injected fluid preferentially goes through high permeability fracture channel and mass transfer between fracture and matrix is mainly due to k*σ. Gravity drainage effect within a thick matrix block would be reduced due to low vertical permeability or k*σz. If k*σ=0, only viscous force is active.
Part-3: Initial estimate of critical water injection rate on oil recovery in field simulation can be calculated from dimensionless fracture capillary number derived from laboratory test. Then reservoir simulation is used to study the sensitivity of water injection rate to obtain optimal injection rate. In general lower injection rate would be favored due to lower viscous force and longer contact time with the matrix.
Unique Artificial Lift Solution for Complex Operation in a Caspian Sea Field Using Jet Pumps
Authors: Berdyev Yunus , El Habashy Ramy 
Published: July 2015

Abstract
Dragon Oil needed to extend the production lifetime for wells with lower than expected natural flow duration. After reviewing multiple options, Dragon Oil chose to implement artificial lift using jet pumps to return the candidate wells to the required production levels. This case study highlights the rationale, implementation, and outcomes from this additional well investment. Candidate wells for jet pump artificial lifting have been drilled from offshore wellhead platform 1 into the crest of the main reservoir production basin. A multiwell hydraulic jet pump system was installed during the spring of 2013.