Polymer Injection to Unlock Bypassed Oil in a Giant Carbonate Reservoir: Bridging the Gap Between Laboratory and Large Scale Polymer Project

2021 ◽  
Author(s):  
Clement Fabbri ◽  
Haitham Ali Al Saadi ◽  
Ke Wang ◽  
Flavien Maire ◽  
Carolina Romero ◽  
...  
Keyword(s):  
High Salinity ◽  
Water Injection ◽  
Cross Flow ◽  
Carbonate Reservoir ◽  
Carbonate Reservoirs ◽  
Laboratory Work ◽  
High Permeability ◽  
Polymer Injection ◽  
Single Well ◽  
Pilot Design

Abstract Polymer flooding has long been proposed to improve sweep efficiency in heterogeneous reservoirs where polymer enhances cross flow between layers and forces water into the low permeability layers, leading to more homogeneous saturation profile. Although this approach could unlock large volumes of by-passed oil in layered carbonate reservoirs, compatibility of polymer solutions with high salinity - high temperature carbonate reservoirs has been hindering polymer injection projects in such harsh conditions. The aim of this paper is to present the laboratory work, polymer injection field test results and pilot design aimed to unlock target tertiary oil recovery in a highly heterogeneous mixed to oil-wet giant carbonate reservoir. This paper focuses on a highly layered limestone reservoir with various levels of cyclicity in properties. This reservoir may be divided in two main bodies, i.e., an Upper zone and a Lower zone with permeability contrast of up to two orders of magnitude. The main part of the reservoir is currently under peripheral and mid-flank water injection. Field observations show that injected water tends to channel quickly through the Upper zone along the high permeability layers and bypass the oil in the Lower zone. Past studies have indicated that this water override phenomenon is caused by a combination of high permeability contrast and capillary forces which counteract gravity forces. In this setting, adequate polymer injection strategy to enhance cross-flow between these zones is investigated, building on laboratory and polymer injection test field results. A key prerequisite for defining such EOR development scenario is to have representative static and dynamic models that captures the geological heterogeneity of this kind of reservoirs. This is achieved by an improved and integrated reservoir characterization, modelling and water injection history matching procedure. The history matched model was used to investigate different polymer injection schemes and resulted in an optimum pilot design. The injection scheme is defined based on dynamic simulations to maximize value, building on results from single-well polymer injection test, laboratory work and on previous published work, which have demonstrated the potential of polymer flooding for this reservoir. Our study evidences the positive impact of polymer propagation at field scale, improving the water-front stability, which is a function of pressure gradient near producer wells. Sensitivities to the position and number of polymer injectors have been performed to identify the best injection configuration, depending on the existing water injection scheme and the operating constraints. The pilot design proposed builds on laboratory work and field monitoring data gathered during single-well polymer injection field test. Together, these elements represent building blocks to enable tertiary polymer recovery in giant heterogeneous carbonate reservoirs with high temperature - high salinity conditions.

scholarly journals Injection-production optimization of carbonate reservoir based on an inter-well connectivity model

2021 ◽  
pp. 014459872199465
Author(s):  
Yuhui Zhou ◽  
Sheng Lei ◽  
Xuebiao Du ◽  
Shichang Ju ◽  
Wei Li
Keyword(s):  
History Matching ◽  
Water Injection ◽  
Field Application ◽  
Carbonate Reservoir ◽  
Production Optimization ◽  
Oil Field ◽  
Carbonate Reservoirs ◽  
Utilization Rate ◽  
Production Volume ◽  
Connectivity Model

Carbonate reservoirs are highly heterogeneous. During waterflooding stage, the channeling phenomenon of displacing fluid in high-permeability layers easily leads to early water breakthrough and high water-cut with low recovery rate. To quantitatively characterize the inter-well connectivity parameters (including conductivity and connected volume), we developed an inter-well connectivity model based on the principle of inter-well connectivity and the geological data and development performance of carbonate reservoirs. Thus, the planar water injection allocation factors and water injection utilization rate of different layers can be obtained. In addition, when the proposed model is integrated with automatic history matching method and production optimization algorithm, the real-time oil and water production can be optimized and predicted. Field application demonstrates that adjusting injection parameters based on the model outputs results in a 1.5% increase in annual oil production, which offers significant guidance for the efficient development of similar oil reservoirs. In this study, the connectivity method was applied to multi-layer real reservoirs for the first time, and the injection and production volume of injection-production wells were repeatedly updated based on multiple iterations of water injection efficiency. The correctness of the method was verified by conceptual calculations and then applied to real reservoirs. So that the oil field can increase production in a short time, and has good application value.

The New Flow Control Devices Autonomously Controlling the Performance of Matrix Acid Stimulation Operations in Carbonate Reservoirs

2021 ◽  
Author(s):  
Mojtaba Moradi ◽  
Michael R Konopczynski
Keyword(s):  
Flow Control ◽  
Dynamic Change ◽  
Injection Rate ◽  
Control Flow ◽  
Carbonate Reservoir ◽  
Operating Conditions ◽  
Carbonate Reservoirs ◽  
High Permeability ◽  
The Impact ◽  
Stimulation Of

Abstract Matrix acidizing is a common but complex stimulation treatment that could significantly improve production/injection rate, particularly in carbonate reservoirs. However, the desired improvement in all zones of the well by such operation may not be achieved due to existing and/or developing reservoir heterogeneity. This paper describes how a new flow control device (FCD) previously used to control water injection in long horizontal wells can also be used to improve the conformance of acid stimulation in carbonate reservoirs. Acid stimulation of a carbonate reservoir is a positive feedback process. Acid preferentially takes the least resistant path, an area with higher permeability or low skin. Once acid reacts with the formation, the injectivity in that zone increases, resulting in further preferential injection in the stimulated zone. Over-treating a high permeability zone results in poor distribution of acid to low permeability zones. Mechanical, chemical or foam diversions have been used to improve stimulation conformance along the wellbore, however, they may fail in carbonate reservoirs with natural fractures where fracture injectivity dominates the stimulation process. A new FCD has been developed to autonomously control flow and provide mechanical diversion during matrix stimulation. Once a predefined upper limit flowrate is reached at a zone, the valve autonomously closes. This eliminates the impact of thief zone on acid injection conformance and maintains a prescribed acid distribution. Like other FCDs, this device is installed in several compartments in the wells. The device has two operating conditions, one, as a passive outflow control valve, and two, as a barrier when the flow rate through the valve exceeds a designed limit, analogous to an electrical circuit breaker. Once a zone has been sufficiently stimulated by the acid and the injection rate in that zone exceeds the device trip point, the device in that zone closes and restricts further stimulation. Acid can then flow to and stimulate other zones This process can be repeated later in well life to re-stimulate zones. This performance enables the operators to minimise the impacts of high permeability zones on the acid conformance and to autonomously react to a dynamic change in reservoirs properties, specifically the growth of wormholes. The device can be installed as part of lower completions in both injection and production wells. It can be retrofitted in existing completions or be used in a retrievable completion. This technology allows repeat stimulation of carbonate reservoirs, providing mechanical diversion without the need for coiled tubing or other complex intervention. This paper will briefly present an overview of the device performance, flow loop testing and some results from numerical modelling. The paper also discusses the completion design workflow in carbonates reservoirs.

scholarly journals The Optimization and Analysis of Hydrocarbon Recovery under Injection of Biopolymer, Synthetic Polymer and Gels in a Heterogeneous Reservoir

2018 ◽  
Vol 7 (1) ◽  
pp. 19-41 ◽  
Author(s):  
Dike Fitriansyah Putra ◽  
Cenk Temizel
Keyword(s):  
Water Injection ◽  
Synthetic Polymer ◽  
Mobility Ratio ◽  
Viscosity Reduction ◽  
Deep Penetration ◽  
Shear Stresses ◽  
Displacement Efficiency ◽  
High Permeability ◽  
Polymer Injection ◽  
Narrow Channels

Water injection is a conventional method which increases the recovery percentage by providing pressure support and displacing oil in the heterogeneous porous medium. In such a displacement process, (low) mobility ratio is important for a more efficient oil displacement by the injected fluid. As such, the mobility ratio can be reduced using the fluids involving gelling agents for increasing in the volumetric sweep. While polymers degrade and break up on experiencing sudden shear stresses and high temperatures, polymer macromolecules are forced to flow into narrow channels and pores where molecular scission processes can take place. Thus, it is of utmost importance to have a strong understanding of the use of the right type and amount of viscosity as a reduction agent. For polymer injection, a comparison of xanthan polymer and synthetic polymer mechanisms was conducted. A commercial full-physics reservoir simulator was coupled with a robust optimization and uncertainty tool to run the model, where a simplified gel kinetics was assumed to form a microgel with no redox catalyst. Water injection continues over all six layers for 450 days, followed by gel system injection for 150 days in the bottom two layers. Water injection was continued to four years. The top four layers have higher horizontal permeabilities, and a high permeability streak is at the bottom of the reservoir to reduce any helpful effects of gravity. Control and uncertainty variables were set to investigate the sensitivity of this process using the coupled optimization and uncertainty tool. Results demonstrate deep penetration of gel and blocking of the high permeability bottom layers. Sensitivity studies indicate the relative merits of biopolymer, xanthan polymer in terms of viscosity effects vs synthetic PAM in terms of resistance factor vs in-situ gelation treatments and their crossflow dependence. Adsorption and retention of polymer and gel are permeability dependent. Considering the potential for application of gel solutions in the U.S. and throughout the world, this study illustrates the relative advantages of different treatments in terms of viscosity reduction in the same model in a comparative way, while outlining the significance of each control and uncertainty variable for better management of reservoirs where displacement efficiency is highly critical.

scholarly journals Fuzzy Logic in Carbonate Reservoir Quality Assessment: A Case Study from Tarim Basin, China

2017 ◽  
Vol 10 (1) ◽  
pp. 195-203
Author(s):  
Weifu Liu
Keyword(s):  
Fuzzy Logic ◽  
Quality Assessment ◽  
Tarim Basin ◽  
Carbonate Reservoir ◽  
Carbonate Reservoirs ◽  
Reservoir Quality ◽  
Pore Throat ◽  
Throat Radius ◽  
Single Well ◽  
Factor Set

Introduction: To address reservoir quality assessment in highly complex and heterogeneous carbonate reservoirs, a methodology utilizing fuzzy logic is developed and presented in this paper. Based on carbonate reservoir characteristics, three parameters reflecting the macroscopic and microscopic of storage abundance, permeability, and median of pore throat radius were selected to establish the factor set and the evaluation criteria. After analysis of core and test data, a membership function is constructed by semi-drop trapezoid method and the weight formula is also determined by reservoir factor sub-index. The developed method then is used to evaluate a carbonate reservoir in the Tarim Basin in China. Based on the result of single well evaluation, the plane classification map of the carbonate reservoir quality is constructed. Results obtained from reservoir quality assessment in the K32 well show that I-level, II-level, and III-level reservoir qualities account for 58%, 37%, 5% of the reservoir, respectively. The results are consistent with the actual production data demonstrating reliability of the proposed method for reservoir quality assessment practices in usually very complex and heterogeneous carbonate reservoirs. Background: Carbonate reservoirs are complex and heterogeneous and this makes their evaluation a difficult task. Objective: To overcome the uncertainties associated with evaluation of complex carbonate reservoirs a reliable method to accurately evaluate carbonate reservoirs is presented. Methods: Fuzzy logic is used to evaluate a carbonate reservoir from Tarim Basin in China. Based on carbonate reservoir characteristics, three parameters reflecting the macroscopic and microscopic of storage abundance, permeability, and median of pore throat radius are selected to establish the factor set and to evaluate the criteria of carbonate reservoir. After the analysis of core and test data, a membership function is reasonably constructed by semi-drop trapezoid method and the weight formula is also determined by reservoir factor sub-index. Results: An effective methodology for the evaluation of reservoir quality in carbonate reservoirs is established by using fuzzy logic. In addition, an example reservoir from China is used to demonstrate the applicability of the developed method. Conclusion: Based on the result of single well evaluation, the plane classification map of the carbonate reservoir is constructed. Favorable zones in the reservoir are also delineated. Evaluation results are consistent with the actual production data of gas and oil which proves that the proposed method is instrumental in reservoir quality assessment.

Study on the Nonlinear Flow Percolation Law in Low Permeability Carbonate Reservoir of HF Oilfield

2014 ◽  
Vol 644-650 ◽  
pp. 5065-5070
Author(s):  
Shuai Jiang ◽  
Zheng Ming Yang ◽  
Xue Wei Liu ◽  
Meng Ting Wang ◽  
Qian Zhang
Keyword(s):  
Oil Industry ◽  
Carbonate Reservoir ◽  
Oil Field ◽  
Carbonate Reservoirs ◽  
Nonlinear Flow ◽  
Low Permeability ◽  
High Permeability ◽  
Threshold Pressure Gradient ◽  
Flow Situation ◽  
Low Permeability Reservoirs

With the development of the global oil industry,the production of the normal or high permeability reservoirs decline rapidly. Therefore, more and more low permeability reservoirs are used to the production stimulation. The oilfields overseas make great contribution to CNPC. The HF oilfield is one oilfield that the CNPC have in overseas. The HF oilfield is mainly the low permeability carbonate reservoirs which make it not easy to economically exploit. Due to the reason that the low permeability carbonate reservoirs present small porosity and the fluid’s flow situation in the low permeability carbonate reservoirs, the flow doesn't obey the Darcy's law. Thus it is greatly necessary to study the non-Darcy percolation characteristics. In this paper, the HF ‘s low permeability is tested and the threshold pressure gradient test is finished ,according to the experiment results, the nonlinear percolation ‘s law ,which is suited to HF-oil field , is illustrated and the reservoir classification is achieved.

Low Polymer Retention Possible in Flooding of High-Salinity Carbonate Reservoirs

2021 ◽  
Vol 73 (11) ◽  
pp. 60-61
Author(s):  
Chris Carpenter
Keyword(s):  
Porous Medium ◽  
High Salinity ◽  
Material Balance ◽  
Synthetic Polymers ◽  
Polymer Flooding ◽  
Carbonate Reservoir ◽  
Carbonate Reservoirs ◽  
Reservoir Rock ◽  
Abu Dhabi ◽  
Polymer Retention

This article, written by JPT Technology Editor Chris Carpenter, contains highlights of paper SPE 202809, “Low Polymer Retention Opens for Field Implementation of Polymer Flooding in High-Salinity Carbonate Reservoirs,” by Arne Skauge, SPE, and Tormod Skauge, SPE, Energy Research Norway, and Shahram Pourmohamadi, Brent Asmari, et al., prepared for the 2020 Abu Dhabi International Petroleum Exhibition and Conference, Abu Dhabi, held virtually 9–12 November. The paper has not been peer reviewed. Polymer flooding has been a successful enhanced-oil-recovery method in sandstone reservoirs for decades. Extending polymer flooding to carbonate reservoirs has been challenging because of adsorption loss and polymer availability for high-temperature, high-salinity (HT/HS) reservoirs. In this study, the authors establish that HT/HS polymers can exhibit low adsorption and retention in carbonate reservoir rock at ultrahigh salinity conditions. Introduction Retention is a key factor for polymer propagation and acceleration of oil production by polymer flooding. In the complete paper, the authors consider HT/HS applications for carbonate reservoirs. Synthetic polymers such as partially hydrolyzed polyacrylamide are not thermally stable at temperatures above 60°C. The thermal stability of the synthetic polymers can be improved by incorporating monomers. To evaluate the retention of polymer in reservoir rock, dynamic retention experiments were performed in the presence and absence of oil. In homogeneous rock, the presence of residual oil typically will reduce the retention proportional to the surface covered by the oil saturation. Strongly heterogeneous rock containing fractures also may have low retention because the fluid flow mainly may be through highly permeable fractures or channels and, consequently, only part of the porous medium will contact polymer. Retention in carbonate matrix displacement (homogeneous rock) was performed on outcrop Indiana limestone for reference, but most experiments were made on reservoir rock material. The polymer used is SAV 10. Experimental Methods The easiest and, in many cases, most-accurate method for quantifying retention in dynamic coreflow experiments is by material balance. This refers to the measurement of the polymer in the effluent. The injected amount minus the backproduced amount of polymer gives the loss caused by transport through the porous medium. The retention includes both adsorption of polymer onto the rock and dynamic loss as the result of mechanical entrapment such as molecular straining and concentration blocking. In most cases, the authors used a passive tracer injected with the polymer and applied two slugs. The first slug quantifies the retention by material balance, but the difference in effluent of the second slug minus the first slug also can give an alternative measurement of the polymer retention. Comparing tracer and polymer effluent concentrations from the second polymer slug quantifies the inaccessible pore volume (IPV). The experimental setup is illustrated in Fig. 1.

Pulling the Production: A New Way of Looking into Brown Field Reservoirs

2021 ◽  
Author(s):  
A.. Ghosh ◽  
J.. Zacharia ◽  
V.. Kumar ◽  
R.. S. Chauhan ◽  
R.. Santhosh Kumar ◽  
...  
Keyword(s):  
Promising Result ◽  
Water Injection ◽  
Qualitative Evaluation ◽  
Oil Production ◽  
Integrated Approach ◽  
Carbonate Reservoir ◽  
Added Value ◽  
High Permeability ◽  
Horizontal Drain ◽  
Water Cut

Abstract One of the major brownfields in offshore India was producing for three decades from main carbonate reservoirs of the Eocene and Oligocene age. Average production of this brownfield is approximately 11,000 barrels of oil per day (BOPD). To maintain the declining reservoir pressure, the field has been under active water injection for more than two decades. However, being a complex carbonate reservoir with high textural heterogeneity, the water-front movement is not very well understood and monitored. To increase the oil production, the operator started drilling horizontal drain-holes from the platforms and has adopted a conventional perforated and blind tubing combination as a completion strategy. However, it was found that wells were performing poorly with very high water cut. An integrated and comprehensive petrophysical workflow was applied that used data analysis and the added value of advanced 3D acoustic data in combination with nuclear magnetic resonance (NMR) data to provide a rapid realistic solution to avoid such high watercut through optimizing the completion strategy. This led to a production gain in this offshore field, which was underperforming as per earlier predictions and expectations. Conventional well-log based qualitative evaluation for horizontal segmentation strategy was rejected in favor of an integrated approach for lateral reservoir facies delineation. Lateral petrophysical property characterization was carried out through quick integration of NMR pore-size driven facies analysis, advanced acoustic radial profiling, anisotropy, and Stoneley analysis. Permeability profiling along the horizontal drain-hole section using NMR and acoustics provided critical insight. Those were integrated to avoid potential high permeability conduits of thief zones for water breakthrough. A rock-quality index was derived to optimize the completion strategy soon after the logging, even preceding the rig-down of the acquisition runs and lowering of the completion. Zones with higher skin, deeper formation damage, and lower rock-mechanical properties were avoided for efficient swell-packer placements. The well started producing and continued production with only 10% water cut along with 450 barrels of oil compared to an average 90% watercut and 100 barrels of oil from the other wells of the same platform, which used the older nonoptimized completion strategy. Based on the promising result for the first well, the same workflow was used for two similar wells of other two different platforms inthe same field, which also resulted in similar production with enhanced oil production and reduced water cut. The study using the rapid integrated evaluation workflow established efficient zonal isolation of high permeability thief zones with accuracy for timely optimization of horizontal well segmentation, which assisted in pulling higher production in this brownfield by reducing unwanted water production.

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