Perforation Length Research Articles

Comparative evaluation of the accuracy of electronic apex locators and cone-beam computed tomography in detection of root canal perforation and working length during endodontic retreatment

BackgroundTo evaluate the accuracy of the electronic apex locators (EALs), and Cone-Beam Computed Tomography (CBCT) scanning, both in working length (WL) determination and in the detection of root canal perforations in retreatment cases.MethodsSixty human mandibular premolars were selected. After crown removal partially and canal access, root canals were instrumented and irrigated. The obturation process utilized gutta-percha and sealer with warm vertical compaction. Two groups were distinguished: one without perforation (Group 1) and the other with an apical third perforation (Group 2). Retreatment included filling removal, apical preparation, and irrigation. Actual working lengths (AWL) were determined using a stereomicroscope. CBCT images were used to measure CBCT working length (CWL), with adjustments for optimal views. Propex II and Dentaport ZX were used to measure electronic working length (EWL). Differences between EWL and AWL, as well as CWL, were analyzed to gauge accuracy. Data underwent Two-way ANOVA analysis. Measurements within ± 0.5 and ± 1 mm tolerance ranges were deemed successful for each device, followed by applying the Pearson Chi-square test.ResultsThe study reveals no significant inter-group variations in device performance (p > .05). Dentaport ZX missed detecting perforation in two Group 2 (apical perforation) cases. For ± 1 mm tolerance, Propex II displayed the highest success in Group 2 (apical perforation).ConclusionThis study demonstrates the comparable performance of Propex II, Dentaport ZX, and CBCT in endodontic retreatment, providing insights into diagnostic reliability.

Nasal Septal Perforation Dimensional Analysis.

To describe and illustrate septal perforation shape through the documentation and analysis of length and height measurements. A secondary objective is to correlate perforation size to surgical and nonsurgical etiologies. Retrospective case series. Tertiary academic medical center. Length and height of consecutively treated perforations over a 3-year period were measured directly or through computed tomography. Mean differences in length and height measurements were compared and regression analysis used to determine perforation shape and the effect of etiology on perforation size. Perforations were classified by length into small (1-5 mm), medium (6-15 mm), and large (>15 mm) and correlated to shape and etiology. One hundred twenty-four patients (mean age 50.4 years, 60.5% female) met study inclusion criteria. Height was less than length in 93% of perforations 5 mm or greater in length. Mean perforation height was significantly less than length for medium and large perforations (P < .001). Mean length and height measurements of nonsurgical perforations were greater than those for surgical perforations (P < .001). Height is less than length in over 90% of septal perforations. Most perforations assume an elliptical shape as they enlarge. Accurate measurement and presentation of length and height is relevant information to perforation management decisions and for the evaluation of treatment outcomes.

Mixing dynamics and recovery factor during hydrogen storage in depleted gas reservoirs

Large-scale hydrogen storage is strategically important for society and depleted gas reservoirs have been proposed as a potential solution. However, the mixing with remaining hydrocarbon gas during injection/production cycles and the impact of different reservoir parameters on the hydrogen recovery factor (RFH2) have not been fully understood. We investigate mixing dynamics and analyze the effects of initial hydrocarbon recovery factor, reservoir permeability, well perforation length, intelligent completion, and fractures on RFH2. Fine-grid gas reservoir models with compositional simulation were used to simulate cyclic hydrogen storage. Mixing of injected hydrogen with remaining hydrocarbon gas occurred in three distinct phases in each cycle: 1) displacement of remaining hydrocarbon gas through pressure-driven flow during hydrogen injection, 2) density-driven flow of gases during the idle time after hydrogen injection, and 3) pressure-driven flow of gases towards the production intervals during the hydrogen production phase. Higher RFH2 s were obtained when the storage process was initiated at higher hydrocarbon gas recovery factors. Storing hydrogen in reservoirs with lower permeability also led to higher RFH2 s, provided the well pressure limits were not an issue. In conditions of a 5× to 15× increase in permeability, the injected hydrogen moved upward and spread laterally, positioning it farther from the wellbore. This made hydrogen production more difficult and placed the mixing zone and hydrocarbon gas closer to perforations. Shorter perforation lengths at the top of the formation resulted in the best RFH2 s. Additionally, intelligent completions (that closed perforations producing gas with low hydrogen content) improved RFH2 by providing the possibility of purer hydrogen production. The presence of natural fractures significantly reduced hydrogen recovery, especially in the first few cycles. However, the influence decreased over time as highly conductive flow paths provided by fractures can contribute to the production of the accumulated unrecovered hydrogen from previous cycles.

Research on water-out mode and differential perforation in thick carbonate reservoir

The development of anti-rhythmic carbonate reservoirs in the Middle East often encounters challenges such as water hold-up and reverse coning during the water injection process, leading to premature water breakthrough and various water-out issues. The unclear understanding of these phenomena, attributed to strong reservoir heterogeneity, results in a relatively low recovery degree in water injection development. This paper investigates the mechanisms behind water hold-up and reverse coning phenomena, offering detailed solutions. Numerical models of the oil reservoirs were developed, and an extensive study of influencing factors, including reservoir types, Kv/Kh, water injection pressure differential, wettability, and perforation position, was conducted to unveil the underlying mechanisms. Key findings indicate that the water hold-up phenomenon is influenced by capillary force barriers due to wettability and high-perm streaks, while the reverse coning phenomenon depends on the combined forces of gravity, capillary force and downward production differential among which downward production differential is the dominant factor compared to capillary force and gravity. The study also proposes a differential perforation principle tailored to different water-out types to enhance vertical sweep efficiency. The differential perforation principle is as follows: the optimal perforation position is at top layer and the optimal perforation length approximately accounts for 1/4 of the total oil layer thickness for water-out in bottom; the avoidance perforation height in top accounts for 1/6 of the total oil layer thickness and the optimal perforation length approximately accounts for 1/2 of the total oil layer thickness for water-out in top; the avoidance perforation height in top and bottom accounts for 1/5 and 2/5 of the total oil layer thickness respectively for water-out in both top and bottom.

Minimally Invasive Robotic-assisted Perforator-to-Perforator DIEP Flap Breast Reconstruction.

Reducing morbidity has been the goal of many reconstructive microsurgery efforts. Several techniques have been described for deep inferior epigastric perforator flap breast reconstruction to minimize abdominal donor-site morbidity. Although these techniques have certain tradeoffs, we designed a minimally invasive robot-assisted perforator-to-perforator approach to achieve minimal donor- and recipient-site morbidity. Simultaneous identification of the deep inferior epigastric artery (DIEA) and internal mammary artery (IMA) perforator was performed, followed by a small fascial incision around the dominant DIEA perforator. The IMA perforator was prepared for a prepectoral anastomosis. The short DIEA pedicle was dissected without further longitudinal fascial incision until an adequate diameter compared with the IMA perforator was reached, and a robot-assisted perforator-to-perforator anastomosis was performed prepectorally. All patients underwent reconstruction performed by a single surgeon. The smallest abdominal incision was 2.5 cm with a DIEP pedicle length of 6 cm. The average IMA perforator diameter was 1.14 mm (1.0 mm-1.2 mm). The average vein diameter was 2.0 mm (1.5-3.0 mm). The incision to closure lasted 330 minutes (313-348 minutes). Flap ischemia was 105 minutes (82-118 minutes), whereas the time for robot-assisted anastomosis was 25 minutes (22-30 minutes). All anastomoses were performed successfully. Our initial experience with robot-assisted perforator-to-perforator anastomosis for DIEP flap breast reconstruction demonstrates promise in achieving minimal patient morbidity. Raising only a very short pedicle can be compensated by adding the prepectoral IMA perforator length and enabling a good size match for small-caliber anastomosis. This technique combines important aspects of most minimally invasive DIEP flap harvests and insets.

Simultaneous Co-surgeon Deep Inferior Epigastric Perforator (DIEP) Flap Breast Reconstructions: Feasibility and Clinical Outcomes.

A co-surgeon model is known to be favorable in microvascular breast reconstruction, but simultaneous co-surgeon deep inferior epigastric perforator (DIEP) flap cases have not been well-studied. The authors hypothesize that performing two simultaneous co-surgeon bilateral DIEP flap reconstructions results in non-inferior clinical outcomes and may improve patient access to care. A single-institution, retrospective cohort study was performed utilizing record review to identify all cases of co-surgeon free-flap breast reconstructions over a 38-month period. Patients who underwent simultaneous bilateral DIEP flap breast reconstructions with the same two co-surgeons were identified. The control group consisted of subjects who underwent non-simultaneous reconstruction by the same co-surgeons within the same, preceding, or following month of those in the study group. Primary outcome variables were 90-day postoperative complications, while secondary outcomes were operating time, ischemia time, and length of stay. Descriptive statistics, univariate and multivariable regression analyses were performed. Overall, 137 subjects were identified and 64 met the inclusion criteria (n=28 study, n=36 control). There were no statistically significant differences between groups in body mass index, radiation, trainee experience, flap perforator number, immediate/delayed reconstruction, or length of stay. There were also no statistically significant differences in complications, including flap loss, anastomosis revision, take-back to the operating room, or re-admission. Operative time was longer in the simultaneous DIEP group (540.5 vs. 443.5 min, p<0.01), but ischemia time was shorter in the simultaneous group (64.0 vs. 80.5min, p<0.01). A simultaneous co-surgeon approach to bilateral DIEP flap reconstruction may improve access to care and does not result in a higher complication rate compared with non-simultaneous bilateral DIEP flaps.

A Cadaveric Study on Perforator Anatomy of the Medial Sural Artery Perforator Flap.

Background The medial sural artery perforator (MSAP) flap was described by Cavadas et al in 2001. The aim of this study was to analyze the flap characteristics in the regional population and was planned as a cadaveric dissection study. Methods Thirty-three legs of fresh cadavers were studied for perforator characteristics, length, and origin of pedicle and skin paddle thickness. Observations were documented and analyzed. Results Seventeen right legs (51.5%) and sixteen left legs (48.5%) were studied. Twenty-five pedicles originated from popliteal artery (86.2%) and four (13.8%) from the common sural trunk. No perforators were seen in four legs. The mean number of perforators is 2 (0-6). The mean distance of perforator from midpoint of popliteal fossa was 10.7 cm (8-13 cm) and from posterior midline it was 3.2 cm. The mean size of the perforator was 1.1 ± 0.8 mm (0.8-1.5 mm). The mean pedicle length was 9.3 ± 1.3 cm. The mean flap thickness was 4.3 ± 0.7 mm (3.0-5.5 mm). There was no correlation for flap or perforator characteristics with side of leg. Conclusion This study concludes that MSAP is a good flap in terms of perforator characteristics, pedicle length, and flap thickness, when a medium sized thin flap with long pedicle is needed. The location of perforator on calf varies in different population. Being a perforator flap, anatomical variability is common and should be thought of while choosing this flap.

Quantifying the impact of geological and construction factors on hydraulic fracture dynamics in heterogeneous rock layers using the phase field method

Hydraulic fracturing, a pivotal practice for optimizing development in tight oil reservoirs, encounters challenges in accurately predicting propagation paths within heterogeneous rock formations. Existing phase models often overlook the influence of complex formations, especially in porous media with heterogeneous characteristics. Addressing this gap, we present a novel phase field method aligned with on-site practices. This innovative approach considers cracks, bedding planes, and faults as heterogeneous structures, integrating directional physical and mechanical properties. The key innovation lies in constructing assignment functions to characterize mechanical and seepage parameters of the rock matrix. Anchored in pore elasticity theory and the principle of energy minimization, we establish and validate a hydraulic coupled phase field model through plaster experiments. This model not only corrects the oversight of formation heterogeneity but also provides a comprehensive analysis of the impact of physical and construction parameters on crack propagation. The study extends to numerical simulation studies on three typical heterogeneous rock layers—natural fractures, bedding planes, and faults. Utilizing indicators like fracture pressure, crack extension length, and damage area, a random forest algorithm quantifies the degree of influence of each factor on fracturing. Our results underscore varying impacts from geological factors (natural fractures, bedding angle, stress difference, elastic modulus, matrix porosity, and permeability) and construction factors (cluster spacing, perforation length, fracturing fluid viscosity, displacement, well spacing, and perforation opening) on the fracturing effect of heterogeneous rock layers. In conclusion, our proposed phase field framework demonstrates predictive capability across diverse heterogeneous situations. This innovative model not only rectifies past oversights but also offers insights unattainable through traditional experimental testing, significantly advancing our understanding of hydraulic fracture dynamics.

Characterization of radial artery perforation patterns using optical coherence tomography

BackgroundThe characterization of radial artery perforation (RAP) patterns using optical coherence tomography (OCT) has not been well established. This study aimed to identify the characteristic RAP patterns in patients diagnosed through post-procedural OCT examination. MethodsThis retrospective study included 1936 consecutive patients who underwent radial artery (RA) OCT following OCT-guided transradial coronary intervention (TRI) from January 2016 to July 2022. Data regarding RAP characteristics were collected through OCT, including the perforation site as well as dimensions such as the length, width, and arc. Furthermore, RAP types were classified as small or large perforations, with a cut-off arc value of ≤90°. ResultsRAP, as identified by RA angiography (RAA) during TRI and on post-procedural OCT, was found in 16 out of 1936 patients (0.83 %). RA OCT imaging showed that the median distance between the RA ostium and the perforation site, the perforation length, width, and arc were 30.6 (14.4–42.2) mm, 1.55 (1.03–1.92) mm, 0.74 (0.60–1.14) mm, and 42.5 (25.0–58.1) °, respectively. Small perforations (arc ≤90°) were observed in 14 out of the 16 (87.5 %) patients with RAP. Post-procedural RAA revealed that 15 out of the 16 (93.7 %) patients with RAP had sealed perforations, with the remaining patient requiring external compression. ConclusionsOur findings demonstrated that RAP is uncommon during TRI, with clearly defined characteristic patterns on OCT. Most RAPs are small and tend to spontaneous seal through catheter tamponade.

(262) Salvage Penile Prosthetic Surgery, Unique Surgical Technique. Institutional Experience

Abstract Introduction `-Penile prosthesis surgery represents the end-stage treatment for erectile dysfunction. It is conventionally used only in cases of erectile dysfunction refractory to pharmacological treatments. -Penile prothesis surgery is associated with a high satisfaction rate and a low complication profile. However, it must be appreciated that the complications of surgery can have devastating consequences on a patient's quality of life and satisfaction and include infection, prosthesis malfunction, penile corporal perforation and penile length loss. -This study discusses the diagnosis and management of infected penile prosthesis with highlighting special intra-operative surgical technique that might be a valuable step in Salvage penile prosthetic surgery Objective Since its introduction in 1996 Mulcahy salvage has significantly improved outcomes for the removal and replacement of infected penile prostheses. Long-term follow up data of Mulcahy salvage show an infection-free rate of 82%. In our study we evaluated the Salvage Penile Prosthetic Surgery Cases done in our tertiary institution since (2000 up to date) and introduce the unique surgical technique that resulted in reduction the re-infetion rate. Methods This is a retrospective, institutional review Results total of 13 Salvage penile prosthetic surgeries done in our tertiary center since between 2000 and 2023 out of them only one case developed reinfection and ended with penile prosthesis removal. Therefor, the rate of re-infection is 8% comparing with latest successe rate of Mulcahy technique (18%) We applied surgical step intra- operative that might be the underling reason of decreasing the the reinfection rate that will be presented in details. Conclusions This retrospective analysis of salvage procedures and replacement of infected penile prosthesis with malleable prosthesis shows a high infection-free rate. Disclosure No.

Septal perforation

Aim: This study isolates septal perforations due to nasal surgery for clinical analysis and their effect on bilateral mucosal flap repair. Methods: This is a retrospective review of a single surgeon’s 20-year experience with endonasal perforation repair utilizing bilateral mucosal advancement flaps supported with an autologous tissue interposition graft. Patients with a minimum of 4-month postoperative follow-up were included in the study. Comparative analyses of repair failure rates and perforation size of failures between surgical and non-surgical etiologies were performed. Results: Three hundred ninety-two patients met the criteria for inclusion in the study. The incidence of perforation and prior septal surgery was 40.6%. Overall repair closure in patients with a minimum of 4 months follow-up was 94.8%. Failures were noted in 5.7% of surgical and 4.7% of non-surgical perforation etiologies (P = 0.816). Mean differences in perforation length and height in failed repairs between non-surgical and surgical etiologies (19.4 vs. 13.7 and 15.5 vs. 9.3 mm, respectively) were significant (P = 0.048 length, P = 0.006 height). Conclusion: Post-surgical nasal septal perforations can be repaired with a low rate of failure. However, this study found that the size of perforations in failed repairs was significantly smaller in patients with a history of septal surgery, suggesting that prior septal surgery increases the technical difficulty of a bilateral flap perforation repair.

A New Experimental Method for Acid Pretreatment in Perforated Horizontal Wells: A Case Study of Mahu Conglomerate Reservoir

The Mahu Oilfield in Xinjiang, China, is the world’s largest conglomerate oilfield, with a daily output of more than 8000 tons. In the fracturing of perforated horizontal wells, the breakdown pressure is high, resulting in difficulties in their treatment. Acid pretreatment has been applied to reduce the breakdown pressure in the field, but with poor performance. Few studies have been conducted on how acid pretreatment affects the breakdown pressure under perforation conditions in the Mahu conglomerate reservoir. Also, existing fracturing or acid pretreatment experiments cannot simulate perforation well. Therefore, a new method was developed to make perforations by hydro jetting the fracturing specimens (300 mm × 300 mm × 300 mm) first. It can achieve specified perforation parameters, including the perforation angle, position, and length. Subsequently, true triaxial hydraulic fracturing experiments were conducted on the conglomerate specimens obtained from the Mahu area. The effects of the acid pretreatment on the fracture initiation and breakdown pressure were investigated by injecting the perforation section of the conglomerate using various acid systems. The study results showed that the perforation made by the new apparatus was extremely close to the perforation on-site. The acid pretreatment effectively dissolved minerals and could decrease the breakdown pressure down to 7.7 MPa. A combination of 6%HF + 10%HCl was recommended for the acid pretreatment in the Mahu conglomerate reservoir. A total of 60 min acid–rock contact time is necessary for sufficient rock dissolution. The mechanism of the acid pretreatment to decrease the breakdown pressure is that the rock dissolution by the acid reduces the rock tensile strength and increases the permeability. The raised permeability increases the fluid pressure of the reservoir near the wellbore so as to reduce the breakdown pressure of the formation. The research results provide technical support for reducing construction difficulty and optimizing parameters in the Mahu Oilfield.

Construction and application of flow pressure drop model of perforated well considering pressure loss of perforation hole

Perforating well is one of the main production wells in reservoir development. Perforating effect directly affects well production, so the optimization of perforating parameters has attracted wide attention. Because pressure difference serves as the driving force for fluid flowing from formation to wellbore, it is important to understand the composition of production pressure difference in perforating well, which can guide the optimization of perforating parameters and the evaluation of perforating effect. In order to clarify the composition of production pressure difference during the production process of perforated wells, a pressure drop model pressure drop model is established based on fluid mechanics theory, which includes a pressure drop model of formation and a pressure drop model of perforation hole. The pressure drop model of formation is firstly constructed based on the Darcy's law and the equivalent resistance method, and the pressure drop model of perforation hole is built by the fluid tube-flow theory. Secondly, the numerical calculation method is adopted to realize the coupling solution of models, and the accuracy of this model is verified by comparison of the Karakas-Tariq model. Finally, the effects of formation physical properties and perforating parameters on flow pressure drop are discussed. The results show that there is a difference of more than 2 orders of magnitude between the pressure drop generated in perforation hole and flow pressure difference, and pressure drop of perforation hole can be neglected in practical applications. Comparing with medium–high permeability reservoirs, optimizing perforation parameters in low permeability reservoirs has a more significant impact on flow pressure drop. Among perforating parameters, perforation length and perforation density have great influence on flow pressure difference, while perforation diameter and phase angle have relatively little influence. These results have certain guiding significance for optimizing perforating parameters in different permeability reservoirs.

Multi-objective optimization of geometrical parameters of laterally perforated on silt fin by gray relation analysis based on Taguchi method

In this paper, slit fin with lateral perforations are presented and the optimal parameters of the perforation on the silt fin are determined. The effects of the three design parameters of perforation length H, perforation height P and tilt angle θ on the j and f-factor are analyzed using gray relation analysis (GRA) base on the Taguchi method (TM). Numerical simulations were performed for different combinations of the three geometric parameters for 16 cases. Based on the Taguchi method (single-objective optimization) analysis, out of the three perforation parameters, the perforation length H exhibited the most pronounced impact on the j-factor, boasting a substantial contribution ratio of 33.1 %. The contribution ratios of the perforation length H, height P, and tilt angle θ influencing the f-factor were determined to be 31.1 %, 46.2 %, and 18.4 %, respectively. The optimal combination of parameters for perforation on the slit fins was obtained by Gray relation analysis (multi-objective optimization) with values of H = 1/3, P = 1 mm and θ = 90°, representing the highest j-factor and the lowest f-factor of the parameter configuration, in contrast to the remaining parameter combinations, the SNR values for its j and f-factor stand at −49.14 and 35.1, respectively while the JF-factor also outperformed those of the other 16 groups of cases. Finally, the results obtained by Taguchi method and GRA are analyzed in conjunction with flow behavior.

Structural behaviour of LDSS tubular beams with web perforation under three-point bending

The paper deals with the numerical study of Lean Duplex Stainless Steel (LDSS) rectangular tubular beams with circular and rectangular web perforation under three-point bending to assess the shear and moment response employing FE software package Abaqus. Various parameters such as cross-section slenderness, perforation depth, perforation length and shape were considered in the study. The results of the FE analysis are then compared to the revised European stainless-steel design regulations. A modification of the currently available European design specification was also proposed based on the numerical study conducted.

Experimental study of hydraulic fracturing initiation and propagation from perforated wellbore in oil shale formation

Perforation hydraulic fracturing is essential in developing unconventional oil and gas resources. This study scales the critical parameters to simulate operations at the field scale, using a true triaxial hydraulic fracturing experimental system to mimic actual far-field stress conditions. The research simulates various scenarios of perforation and fracturing fluid parameters, which significantly influence fracture propagation behaviour and fracture network morphology. The results showed that the initiation pressure required for fracturing with perforation is 20.91% lower than that of open-hole fracturing. Multiple fractures, including bedding and branch fractures, exhibit cross-propagation behaviour, forming barrier-type morphology. Induced by perforation, hydraulic fracture initiation and propagation occur along the direction of maximum geo-stress, but unreasonable orientation and reduction in perforation length can also increase initiation pressure. The flow rate and viscosity of fracturing fluid are positively proportional to the initiation pressure. A high flow rate of 100 mL/min facilitates the generation of bedding fractures, enhances the bedding fractures connectivity and increases fracture network complexity. However, the increase in viscosity forces hydraulic fracture to penetrate the bedding plane directly and diminishes the complexity of the fracture network. Compared to the pressure build-up phase, fluctuations in the fracturing curve during the propagation phase are significantly related to the complexity of the fracture network. Small-scale structural surfaces developed within the strata can become part of the hydraulic fractures and increase the fracture network complexity. Additionally, the hydraulic fractures are captured and hindered by large-scale structural surfaces, forming a single fracture morphology. The findings significantly aid in predicting fracture propagation and fracture network morphology in oil shale exploitation.

Autologous Interposition Grafts for Mucosal Flap Septal Perforation Repair.

Background: Nasal septal perforation repair is commonly attempted utilizing bilateral nasal mucosal flaps supported with an interposition graft. Objectives: To compare the failure rates for bilateral flap repairs utilizing four different autologous interposition grafts. Methods: This is a retrospective review of a single surgeon's bilateral flap perforation repairs supported with an autologous interposition graft. Study inclusion over the 18-year review period required at least one examination 1 month after surgery. Repair failure rates were calculated and compared for each graft type, and logistic regression was performed for multivariate analysis. Results: For the 356 study patients, median (range) age was 51 years (14-81) and 63.0% were women. Mean (range) perforation length was 13.9 mm (1-45). Median (range) at last follow-up was 11.2 months (1-192). Graft types used (percentage of patients and failure rate) were temporalis fascia (58.7/4.4), septal cartilage (23.3/7.3), auricular perichondrium (13.8/4.1), and septal bone (4.2/6.7) (p > 0.05). Conclusion: There was no significant difference in bilateral mucosal flap perforation repair failure rate when either a temporalis fascia, septal cartilage, auricular perichondrium, or septal bone interposition graft was used.

Evaluation and optimization of a horizontal well-triplet for CO2 plume geothermal harvest: Comparison between open and close reservoirs

Depleted oil/gas reservoirs can be used for CO2 sequestration and utilization; CO2 plume geothermal (CPG) production from a CO2 geological storage reservoir has emerged as a viable approach owing to its favorable thermodynamic properties. However, most oil/gas reservoirs are separated by faults into geological blocks, and the impact of these fault boundaries on CPG performance remains unclear. This study evaluated and compared the technical performances of a horizontal well-triplet placement and CPG operation in a thin geothermal reservoir between open and close boundaries. A meta-model simulation–optimization framework was also applied for the economic assessment of both systems. For each boundary system, 200 samples of the horizontal well-triplet design, including injection well overpressure, horizontal perforation length of injection and production wells, and distance between injection and production well, were derived from a 4D-parameter space constrained by particular ranges. These 200 samples of input parameters yielded 200 numerical models for the simulation of CPG operations. A suite of technical metrics, including lifespan, injected, produced, and stored CO2, recovered heat energy, and produced heat flux, were computed from the model simulations for technical performance evaluations. Meta models for economic objectives were developed based on the 200 input–output datasets and used in optimization. A multi-objective particle swarm optimization (MOPSO) approach was utilized to obtain the appropriate optimal designs of the well-triplet for the two boundary systems. The results indicated that performance of both systems was controlled by the well space, which was positively correlated to CO2 storage and total heat recovery but negatively to power plant capacity. High horizontal well lengths and overpressure facilitated CO2 storage, heat recovery, and plant capacity. The open system could generate much more overall profit than the close system owing to CO2 storage income.

Technique Evaluates Polymer Injectivity in High-Salinity/High-Temperature Carbonates

_ This article, written by JPT Technology Editor Chris Carpenter, contains highlights of paper SPE 211451, “Assessment of World-First Two-Polymer Injectivity Tests Performed in Two Giant High-Salinity/High-Temperature Carbonate Reservoirs Using Single-Well Simulation Models and Pressure-Falloff Analysis,” by Juan M. Leon, Shehadeh K. Masalmeh, SPE, and Ali M. Al-Sumaiti, SPE, ADNOC, et al. The paper has not been peer reviewed. _ The complete paper presents the interpretation of two polymer injectivity tests (PITs) performed in two giant light-oil high-salinity/high-temperature (HS/HT) carbonate reservoirs onshore Abu Dhabi. The detailed data acquired in both tests were used to evaluate both polymer injectivity at representative field conditions and in-depth mobility reduction. The interpretation of the pressure transient analysis (PTA) of the pressure falloffs (PFOs) and the mechanistic 3D simulation models of the two PITs confirmed the generation of polymer banks and demonstrated effective propagation of the polymer into the reservoirs at target concentrations and representative rates of future interwell pilots. Introduction The reservoirs tested in the PITs can be described as heterogeneous carbonate reservoirs divided into upper and lower zones. Upper-zone porosities range between 20 and 30%; permeability ranges from 10 to 1000 md. In contrast, the lower zone has porosities and permeabilities ranging from 10 to 30% and from 1 to 20 md, respectively. The main production mechanisms in the reservoirs are peripheral water injection, middip-pattern water injection, and crestal hydrocarbon gas injection in the gas cap. The reservoirs have been developed through long horizontal wells oriented into the lower zones to allow a more-homogeneous sweep. However, the injected fluids in the lower zone travel quickly through the upper zone not far from the injection wells and around the producers into the lower zone. This water or gas inverse coning results in bypassed oil in the lower zone. To face this challenge, the operator has investigated simultaneous injection of miscible CO2 gas and polymer (SIMGAP) for reservoirs with an approximately 10-fold permeability contrast between the lower and upper zones and simultaneous injection of water and polymer (SIWAP) for reservoirs with a permeability contrast of 100-fold or greater between the lower and upper zones. These techniques rely on reducing mobility by polymer injection in the upper zone to provide a pressure barrier and reduce crossflow of the higher-mobility fluid injected into the lower zone. PIT Simulation Model Setup A single-well radial simulation model was built for PIT 1 to assess near-wellbore phenomena by minimizing in-situ velocity and shear-rate calculation errors compared with Cartesian coordinate grids. For interpretation of PIT 2, a mechanistic Cartesian 3D thermal black-oil simulation model was built by extracting a subsector from the last available static geomodel, preserving well architecture and grid resolution in the extracted subsector. The radial simulation model was found unsuitable for PIT 2 because the injector well presented a very high deviated section in the target reservoir, while the long string presented a long horizontal section. Therefore, the polymer injectivity and polymer bank propagation in the upper reservoir might not be represented properly using a vertical well. Different local-grid-refinement (LGR) levels were implemented around the perforation length (upper zone), while the lower zone was in the root grid. The minimum cell radius in the model was determined to be 1.3 ft to avoid errors in well-index calculations considering the well-flow model. Thus, three LGR levels were applied.

Transient Productivity Analysis and Completion Parameter Optimization of Perforating Herringbone Wells.

Herringbone wells are of great significance in tapping the potential of remaining reservoirs, improving recovery efficiency, and reducing development costs and have been widely used in oilfields, especially offshore oilfields. Due to the complex structure of herringbone wells, there is mutual interference between wellbores during seepage, resulting in complex seepage problems, and it is difficult to analyze the productivity and evaluate the perforating effect. In this paper, considering the mutual interference between branches and perforations, a prediction model of transient productivity of perforated herringbone wells was derived based on the theory of transient seepage, and the complex structure with any number of branches, arbitrary configurations, and orientations in three-dimensional space could be considered in this model. The formation pressure in reservoir points at different production times, IPR curves, and the radial inflow of herringbone well were studied by the line-source superposition method, which directly reflected the process of productivity and pressure change, avoiding the one-sidedness caused by using a point source to replace the line source in the stability analysis. Then, through the productivity calculation of different perforation schemes, the influence curves of perforation density, perforation length, perforation phase angle, and perforation radius on unstable productivity were obtained. Orthogonal tests were performed to obtain the degree of impact of each parameter on productivity. Lastly, the selective completion perforation technology was adopted. When the shot density at the end of the wellbore was increased, the productivity of herringbone wells could be improved economically and effectively. According to the above study, a scientific and reasonable construction scheme is recommended for oil well completion construction, which provides a theoretical basis for the improvement and development of perforation completion technology.