Waterflood in a Tight, Heterogeneous, Water-Sensitive, and Massively Fractured Reservoir

2020 ◽  
Author(s):  
R. Arnold
Keyword(s):  
Simulation Study ◽  
Damage Mechanism ◽  
Recovery Factor ◽  
Reservoir Pressure ◽  
Fractured Reservoir ◽  
Initial Value ◽  
Injection Simulation ◽  
Sandstone Formation ◽  
Bottomhole Pressure ◽  
Annual Decline

The T-K Formation is a tight, heterogeneous, and water-sensitive sandstone formation. To enable production, most wells in this reservoir are hydraulically fractured. After a successful massive fracturing campaign, which boosted the production up to 7,500 BOPD, the exploitation led to a dramatic pressure decline. The reservoir pressure had declined from initial value of 1,230 psi down to 450 psi in only six years. A waterflood project was then prepared and implemented in 2009, by converting watered-out producers into injectors, to increase the reservoir pressure as well as to improve recovery factor. Comprehensive studies and thorough surveillance activities were carried out to ensure the success of the project. As results of the on-going operation, the reservoir pressure is increased, enabling more infill drillings and hydraulic fracturing programs to be performed. Field annual decline rate is decreased from 63% to 32%. In addition, some wells that were dead due to insufficient reservoir pressure are brought back to production after the threshold bottomhole pressure is exceeded. To date, recovery factor is 14% and has surpassed the predicted ultimate waterflood recovery factor of 13.4% by the pre-injection simulation study; the pre-injection simulation study indicated a depletion RF of 9%. In terms of cumulative oil production, the waterflood is expected to contribute around 11.4 MMstb of oil. This paper summarizes the journey of T-K waterflood development. This includes pre-injection reservoir characterizations, formation damage mechanism analyses, and practical surveillance activities performed. The workflow and analyses presented in this paper can be used as a benchmark for managing a waterflood project, especially in reservoirs with similar challenges.

Solid Fast-Track Evaluation Methodology: Supporting the Decision-Making Process in the Development of Mature Assets

2021 ◽  
Author(s):  
Rubén Dario Gutiérrez Bedoya ◽  
Claudio Marcelo Fonseca ◽  
Michelle Alba Naranjo Leon
Keyword(s):  
Water Management ◽  
Fast Track ◽  
Production Optimization ◽  
Recovery Factor ◽  
Evaluation Methodology ◽  
Current Status ◽  
Reservoir Pressure ◽  
Service Contracts ◽  
Integrated Methodology ◽  
Management Issues

Abstract As most oilfields in Ecuador are approaching to the end of the service contracts under an advanced degree of maturity, it was imperative to implement a fast-track integrated methodology that supports the decisionmaking process during assets' evaluation. This practice aimed to identify new business opportunities and assure the rehabilitation of brownfields. These fields became a target for investors willing to intervene in new joint ventures with moderate risk to boost production and returns. The methodology is prepared to overcome specific challenges such as severe reservoir pressure depletion, harsh water management issues, facilities constraints and integrity. All this while keeping economics and safe operational standards. This process is divided into five stages: First, the diagnosis of field challenges and associated risks, so that review the current status of subsurface and surface aspects. Then, the following three parallel phases are focused on the study of reservoir architecture, dynamics and performance. Finally, the remaining potential of the asset is assessed by integrating action plans to take advantage of current facilities capacities. This workflow was implemented for the evaluation of three assets: Asset 1: Mature field with a secondary gas cap where its current reservoir pressure is 800 psia (initial pressure 4,200 psia). The asset was evaluated in fifteen (15) days resulting in an integrated solution with 14 activities: conversions to injectors, water source, upsizing, reactivations, change zone, and new wells. The results presented an incremental recovery factor of 6% (by 2028) with an expected production peak of 3,500 BOPD (by 2021). Asset 2: A field producing from two main reservoirs with harsh water management issues under a non-monitored waterflooding scheme with challenging sweet spots identification was evaluated in 10 days, resulting in a redevelopment plan considering: production losses optimization, sixteen (16) activities: workovers, dual completions, new wells, reentry, shut-in, and conversion to water injectors. This evaluation delivered an incremental recovery factor of 10% (by 2029). Asset 3: Producing for around one-hundred (100) years with 3,000 wells drilled. There was a lack of pressure support and facilities and well completions integrity. The fast-track assessment focused on production optimization lasted fifteen (15) days, resulting in one-hundred eighteen (118) wells for reactivation representing an additional recovery factor of 3% (by 2029). This work supported the process for contract's renegotiation and assets' acquisition. This integrated methodology aimed to maximize the assets' value while considering the involved shareholders' needs. Each asset was analysed in an integrated and collaborative manner through the propper resources identification and the usage of the latest technology and workflows. High-resolution reservoir simulation, complex python scripts, and a chemical processes simulator were used to perform an in-depth evaluation and meet the expectations.

Near-Wellbore Hydraulic Fracture Non-Planar Propagation and Torturous Morphology in Tight Sandstone Formation

2021 ◽  
Author(s):  
Ruxin Zhang ◽  
Qinglin Shan ◽  
Wan Cheng
Keyword(s):  
Stress Distribution ◽  
Fracture Initiation ◽  
Damage Mechanism ◽  
Fracture Morphology ◽  
Propagation Model ◽  
Hydraulic Fractures ◽  
Tight Sandstone ◽  
Propagation Behavior ◽  
Stress Shadow ◽  
Sandstone Formation

Abstract In this paper, a 3D near-wellbore fracture propagation model is established, integrating five parts: formation stress balance, drilling, casing and cementing, perforating, and fracturing, in order to investigate fracture initiation characteristics, near-wellbore fracture non-planar propagation behavior, and torturous hydraulic fracture morphology for cased and perforated horizontal wellbores in tight sandstone formation. The method is based on the combination of finite element method and post-failure damage mechanism. Finite element method is used to determine the coupling behavior between the pore fluid seepage and rock stress distribution. Post-failure damage mechanism is adopted to test the evolution of hydraulic fractures through simulating rock damage process. Moreover, a user subroutine is introduced to establish the relation between rock strength, permeability, and damage, in order to solve the model. This model could simulate the interaction between fractures during their propagation process because of the stress shadow. The simulation results indicate that each operation could cause redistribution and reorientation of near-wellbore stress. Therefore, it is important to know the real near-wellbore stress distribution that affects near-wellbore fracture initiation and propagation. Initially, hydraulic fractures initiate independently from each perforation and propagate along the direction of maximum horizontal stress. However, hydraulic fractures divert from original direction gradually to interconnect and overlap with each other, because of stress shadow, resulting in non-planar propagation behavior. Individual fractures coalesce into a spiral-shaped fracture morphology. In addition, a longitudinal fracture could be observed because of wellbore effect, which is a result of weak cementing strength or near-wellbore weak plane. Finally, the complex and torturous fracture morphologies are created near the wellbore, incorporating Multi-spiral shaped fracture and horizontal-vertical crossing shaped fracture. However, the propagation behavior of fracture far away from wellbore is controlled by in-situ stress, forming a planar fracture. The highlights of this 3D near-wellbore fracture propagation model are following: 1) it considers near-wellbore stress change caused by each construction to ensure the accuracy of near-wellbore stress distribution; 2) it achieves 3D simulation of fracture initiation and near-wellbore propagation from perforations; 3) the interaction between fractures is involved, resulting in complex and torturous morphology. This model provides the theoretical basis for fracture initiation and propagation, which also could be applied into heterogenous formations considering the effect of discontinuities.

Simulation Study on High-Powered Shaped Charge Warhead Penetrating into Target with Water Layer

2014 ◽  
Vol 532 ◽  
pp. 342-345
Author(s):  
Shi Long Xing ◽  
Xiang Ke Huang
Keyword(s):  
Numerical Simulation ◽  
Simulation Study ◽  
Water Layer ◽  
Damage Mechanism ◽  
Shaped Charge ◽  
Shaped Charge Jet

A kind of tapered and spherical combined liner shaped charge warhead is researched, and the damage mechanism is analyzed. The physics modle of warhead to columniform hull target is build, numerical simulation is done. The result shows that the shaped charge jet formed by this structure can provide movement space, which is in favor of damaging target with water layer.

scholarly journals RESERVOIR PERFORMANCE ANALYSIS USING MATERIAL BALANCE METHOD IN GAS FIELD

2021 ◽  
Vol 2 (2) ◽  
pp. 68
Author(s):  
Indah Widiyaningsih ◽  
Panca Suci Widiantoro ◽  
Suwardi Suwardi ◽  
Riska Fitri Nurul Karimah
Keyword(s):  
Flow Rate ◽  
Gas Flow ◽  
Material Balance ◽  
Gas Production ◽  
Recovery Factor ◽  
Reservoir Pressure ◽  
Gas Flow Rate ◽  
Reservoir Performance ◽  
Cumulative Production ◽  
Material Balance Method

The RF reservoir is a dry gas reservoir located in Northeast java offshore that has been produced since 2018.  The RF reservoir has produced 2 wells with cumulative production until December 2019 is 31.83 BSCF. In January 2018 the gas production rate from the two wells was 36 MMSCFD and the reservoir pressure at the beginning of production was 2449.5 psia, peak production occurred in April 2019 with a gas flow rate of 98 MMSCFD but in December 2019 the gas production rate from both wells decreased to 30 MMSCFD with reservoir pressure decreased to 1607.8 psia. Changes in gas flow rate and pressure in the RF reservoir will affect changes in reservoir performance, so it is necessary to analyze reservoir performance to determine reservoir performance in the future with the material balance method. Based on the results the initial gas in place (IGIP) is 80.08 BSCF. The drive mechanism worked on the RF reservoir until December 2019 was a depletion drive with a recovery factor up to 88% and a current recovery factor (CRF) is 40%. The remaining gas reserves in December 2019 is 39 BSCF and the reservoir will be made a production prediction until December 2032. Based on production predictions of the four scenarios, scenario 2 was chosen as the best scenario to develop the RF reservoir with a cumulative production is 66.1 BSCF and a recovery factor of 82.6%.

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