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Evans E.,Schlumberger | Ghalambor A.,Oil States International | Orangi A.,Hess
SPE International Formation Damage Control Symposium Proceedings | Year: 2016

One of the main challenges of producing tight or low-permeability gas reservoirs is condensate banking when production starts as the reservoir pressure drops below the dewpoint pressure. Condensate banking causes formation damage and subsequently damages production. The normal procedure to mitigate condensate banking is to hydraulically fracture the well to bypass the condensate bank and improve production from that well. Modeling the condensate banking along the hydraulic fracture is critical to understanding the loss of productivity. We investigated the feasibility of simulating a cyclic CO2 injection scheme to mitigate formation damage due to gas condensate dropout in a low-permeability gas reservoir. The field was modeled using a tartan grid to be able to model the hydraulic fracture explicitly. In addition to the hydraulic fracture, the study examined how much of a role the condensate-gas ratio (CGR) plays in the condensate banking and how to best position a well in a low-, medium-, and high-CGR fluid. For the mitigation phase, different cyclic parameters such as injection rate, injection pressure, and soaking time for the cyclic CO2 injection were considered. The study found that the volume of the GCR played a critical role in determining injection rates and pressure to best be able to mitigate damage due to condensate banking. Copyright 2016, Society of Petroleum Engineers.


Strutt J.,Astrimar | Wells D.,Hess
Proceedings of the Annual Offshore Technology Conference | Year: 2014

API PvP 17N provides a structured approach which organizations can adopt to manage risk and uncertainties related to reliability and integrity performance throughout the life of a project. This may range from the management of general project risk through to the identification and removal of potential failure modes in particular equipment. The basic approach is simple and consistent, and when applied correctly has the potential to greatly reduce the financial risk of designing, manufacturing, installing and operating subsea equipment and/or systems. This paper presents the principals and approaches used in API 17N, what it is in general, and why it was written. It will describe the status of its update, including the reasons for the revision and the addition of Integrity Management. It will not cover the detail of the RP, but instead it will describe the underlying paradigm and key processes and how it is being written to facilitate and enable wider application to other technical disciplines. Finally the paper will outline its relationship to other API documents, standards and industry initiatives and what we have learnt from the recent events. Copyright © 2014, Offshore Technology Conference.


Evans E.,Schlumberger | Ghalambor A.,Oil States International | Orangi A.,Hess
Proceedings - SPE International Symposium on Formation Damage Control | Year: 2016

Horizontal wells with multistage hydraulic fractures have become the most common practice to obtain viable commercial production from shale and tight gas reservoirs. With a marked increase of gas production emerging from these tight reservoirs, it is necessary to further study the effects of formation damage due to condensate dropout and how best to prevent and mitigate this damage. There are two common ways to mitigate and treat condensate banking. The first method is to fracture the existing well. This allows bypassing the condensate and therefore increasing well productivity. The second method is to shut-in the well and allow pressure to build up so that the dropped out liquids are revaporized back into the gas. These options, respectively, involve large capital expenses and temporary decrease of production. Before deploying these solutions, the condensate dropout damage can be strongly reduced at no (field) cost by optimizing the well location. This objective in this study was to determine the optimum well location to mitigate formation damage due to condensate dropout in a tight gas well. Compositional reservoir simulations were conducted with different condensate gas ratios and relative permeability curves to quantify the loss of productivity due to formation damage under different conditions. The target formation was 100 ft thick, and a tartan grid was used to represent the hydraulic fractures within the tight gas well. This study determined that well placement plays a key role in preventing damage due to condensate banking. The optimized placement of the well can drastically enhance the viability of a project by allowing for a larger recovery. Copyright 2016, Society of Petroleum Engineers.


Duhon H.,GATE | Cronin J.,Hess
Society of Petroleum Engineers - SPE E and P Health, Safety, Security and Environmental Conference - Americas 2015 | Year: 2015

A HAZOP is a team-based process hazard analysis (PHA) method. Its purpose is to identify hazards and operability issues in a process design. In some HAZOPs, identified issues are evaluated for risk. An effective risk assessment method allows the HAZOP participants and the project team to focus their time and energy on the more significant hazards. Risk assessments in HAZOPs are typically performed using a simple risk matrix (Figure 2). In the risk matrix approach, participants make judgments as to the potential severity and the likelihood of an event. The combination of severity and likelihood indicates the risk. The risk matrix will often be color coded with green areas (OK), red areas (Unacceptable) and yellow areas (improvement suggested, subject to ALARP). This approach is problematic for a number of reasons: 1. The judgment of consequence severity is difficult and is often ambiguous. Any identified scenario could play out in multiple ways often with dramatically different severities. 2. Estimation of the frequency or likelihood of the event is also difficult; especially so if the frequency of the mitigated event is to be estimated. 3. The simple green, yellow, red bands do not provide sufficient resolution for ranking scenarios (the yellow band may span two or three orders of magnitude, for instance). This paper presents a more rigorous and repeatable approach to making the severity and frequency judgments that is also simpler and quicker. The method is, in effect, a simplified layer of protection analysis (LOPA). The authors show how LOPA techniques can be simplified and applied in a HAZOP setting for both frequency and consequence severity judgments. These simplified techniques make such judgments more rigorous and repeatable. Also, because the guesswork is removed, this saves time in the HAZOP. The proposed approach also yields a HAZOP record that is more easily used for a future LOPA study. Copyright 2015, Society of Petroleum Engineers.


Russek J.,Baker Hughes Inc. | Harbaugh C.,Hess
Society of Petroleum Engineers - SPE International Conference and Exhibition on Oilfield Scale 2014 | Year: 2014

In the Rocky Mountain region of the United States, high-salinity brines (total dissolved solids > 250, 000 mg/L) present during oil and gas production cause severe scale problems in the Williston Basin. The scales include not only calcium carbonate, calcium sulfate, barium sulfate, strontium sulfate, but also sodium chloride (halite). This paper presents the development of test methods and their corresponding testing results for scale inhibitor evaluations in the laboratory and their applications in the field for high-salinity brines. It is well known that there is no effective test method for halite scale inhibitor laboratory testing due to the difficulty of controlling the amount of halite precipitation and reproducibility in the test. The evaluation of scale inhibitor performance was conducted by using a tube-blocking test and a static bottle test with synthetic high-salinity brines from the Williston Basin. Two sets of brines were designed, based on the field brine, and were tested with two methods. One set of brine was for halite scale inhibitor evaluation by mixing near-saturated NaCl synthetic brine with a highly concentrated brine of CaCl2-2H2O+ NaCl. The second set of brine was designed to evaluate scale inhibitor performance on calcium carbonate, calcium sulfate, barium sulfate, and strontium sulfate by modified brines. Three types of scale inhibitors were used for the performance evaluations, including halite scale inhibitors, general scale inhibitors, and a multifunctional scale inhibitor. The lab test results showed the multifuntinal scale inhibitor exhibited good scale inhibition performance for both sets of scale testing. Successful scale inhibitor implementations in the field applications and case history are also presented in this paper. Copyright 2014, Society of Petroleum Engineers.


Patent
Hess and Betzig | Date: 2012-05-16

First activation radiation is provided to a sample (601) that includes phototransformable optical labels (PTOLs) to activate a first subset of the PTOLs in the sample (601). First excitation radiation is provided to the first subset of PTOLs in the sample (601) to excite at least some of the activated PTOLs, and radiation emitted from activated and excited PTOLs within the first subset of PTOLs is detecting with imaging optics (602). The first activation radiation is controlled such that the mean volume per activated PTOLs in the first subset is greater than or approximately equal to a diffraction-limited resolution volume (DLRV) of the imaging optics (602).The first activation radiation and/or the first excitation radiation is provided to the sample (601) through a multi-photon absorption process. The PTOLs may be formed by photoactivated or photoswitched fluorescent proteins. The method and the apparatus allow to obtain superresolution images.


Patent
Hess and Betzig | Date: 2012-05-16

The invention relates to a method of imaging and a corresponding optical system characterized by a diffraction-limited resolution volume. Within the method, a sample is imaged comprising a plurality of transformable optical labels distributed in at least a portion of the sample with a density greater than an inverse of the diffraction-limited resolution volume of the optical system. The method includes the steps of activating a first subset of the labels in the portion of the sample, wherein the density of the labels in the first subset is less than the inverse of the diffraction-limited resolution volume; exciting a portion of the labels in the first subset of labels, in particular by using excitation radiation; detecting radiation emitted from the activated and excited labels in the first subset of labels with the imaging optics; and determining locations of activated and excited labels in the first subset of labels with a sub-diffraction-limited accuracy based on the detected radiation emitted from the activated and excited labels. The transformable optical labels may be formed by photoactivated or photoswitched fluorescent proteins. The method and the optical system allow to obtain superresolution images.


Patent
Hess and Betzig | Date: 2012-05-16

First activation radiation is provided to a sample that includes phototransformable optical labels (PTOLs) to activate a first subset of the PTOLs in the sample. First excitation radiation is provided to the first subset of PTOLs in the sample to excite at least some of the activated PTOLs, and radiation emitted from activated and excited PTOLs within the first subset of PTOLs is detecting with imaging optics. The first activation radiation is controlled such that the mean volume per activated PTOLs in the first subset is greater than or approximately equal to a diffraction-limited resolution volume (DLRV) of the imaging optics.The polarization of at least one of the activation radiation and the excitation radiation provided to the sample is controlled. The PTOLs may be formed by photoactivated or photoswitched fluorescent proteins. The method and the apparatus allow to obtain superresolution images.


Patent
Hess and Betzig | Date: 2012-05-16

The invention relates to a method comprising steps of: providing spatially-structured activation radiation having relatively high- and relatively low-intensity regions to a sample that includes phototransformable optical labels (PTOLs) to activate a subset of the PTOLs in the sample located predominately at relatively high intensity regions of the spatially-structured activation radiation; providing spatially-structured excitation radiation to the subset of activated PTOLs in the sample, wherein the exciting radiation is structured so that one or more relatively high intensity regions of the excitation radiation at least partially overlap one or more relatively high intensity regions of the activating radiation; detecting radiation emitted from the activated and excited PTOLs with imaging optics; and controlling the intensities and spatial structures of the activating radiation and the exciting radiation so that radiation emitted from PTOLs in the sample is emitted substantially from at least one volume that is comparable to or less than a diffraction-limited resolution volume (DLRV) of the imaging optics. The PTOLs may be formed by photoactivated or photoswitched fluorescent proteins. The invention also relates to a corresponding system.


Patent
Hess and Betzig | Date: 2012-05-16

First activation radiation is provided to a sample (601) that includes phototransformable optical labels (PTOLs) to activate a first subset of the PTOLs in the sample (601). First excitation radiation is provided to the first subset of PTOLs in the sample (601) to excite at least some of the activated PTOLs, and radiation emitted from activated and excited PTOLs within the first subset of PTOLs is detecting with imaging optics (602). The first activation radiation is controlled such that the mean volume per activated PTOLs in the first subset is greater than or approximately equal to a diffraction-limited resolution volume (DLRV) of the imaging optics (602).The sample (601) comprises at least a first species and a second species of PTOL, which are distinguished from each other based on at least one of emission characteristics of the first and second species and excitation characteristics of the first and second species. A density of each species of PTOL in the sample is greater than the inverse of DLRV of the imaging optics, and a density of species of PTOL in the first subset of activated PTOLs of that species is less than the inverse of the diffraction-limited resolution volume. The PTOLs may be formed by photoactivated or photoswitched fluorescent proteins. The method and the apparatus allow to obtain superresolution images.

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