Application of Successful New Downhole Fluid Sampling Technique in Ultra Low Permeability Reservoir in Abu Dhabi Onshore

Downhole reservoir fluids sampling in tight formations has been a continuous challenge due to various reasons. The paper presents a technique of successfully collecting downhole fluid samples for first time in ultra-low permeability reservoir having a history of deep invasion. This became possible by initiating micro-scale fractures followed by pumping out for sampling. Using this technique, downhole formation fluid samples were collected, clean-up time was optimized, in addition to acquiring in-situ stress information during the process. A preliminary assessment was performed using open hole formation evaluation logs and pore pressure measurements to identify the most suitable zones for stress measurement and fluid sampling. Single packer sleeve fracture initiation tests were performed to break down the high stress dense layers. In the reservoir rock, the stress measurement involving initiation of a micro-scale fracture was followed by pumping out formation fluid from the fractured zones to collect clean formation fluid samples. The formation breakdown and fracture closure pressure were measured successfully to calibrate minimum and maximum lateral tectonic strains which were valuable inputs for designing the hydraulic fracturing treatment. In the offset wells, fluid sampling attempts from this zone of interest have proven unsuccessful after multiple attempts involving pumping out over 300 liters because of the high depth of invasion leading to a thick flushed zone around the wellbore. The process of initiating micro-scale fractures followed by pumping out provided a high permeability flow channel for efficient fluid sampling. The near wellbore fractures resulted in pumping at higher rates and reaching the higher oil saturated zones of this deeply invaded formation. Hence, formation fluid samples were successfully collected in spite of the low permeability and high invasion typically encountered in this reservoir. Unlike the unsuccessful sampling attempts in the offset wells, this technique of initiating micro-scale fractures in the reservoir rock followed by pumping out helped in collecting formation fluid samples. This technique can be used to collect reservoir fluid samples from micro-Darcy formations and unconventional reservoirs by improving the flow through the induced fractures and thereby reducing the uncertainty that may persist in failing to collect samples from such zones.

The Role of Rock Matrix Permeability in Controlling Hydraulic Fracturing in Sandstones

A concomitant effect of a hydraulic fracturing experimenting is frequently fluid permeation into the rock matrix, with the injected fluid permeating through the porous rock matrix (leak-off) rather than contributing to the buildup of borehole pressure, thereby slowing down or impeding the hydro-fracturing process. Different parameters, such as low fluid viscosity, low injection rate and high rock permeability, contribute to fluid permeation. This effect is particularly prominent in highly permeable materials, therefore, making sleeve fracturing tests (where an internal jacket separates the injected fluid in the borehole from the porous rock matrix) necessary to generate hydraulic fractures. The side effect, however, is an increase in pressure breakdown, which results in higher volume of injected fluid and in higher seismic activity. To better understand this phenomenon, we report data from a new comparative study from a suite of micro-hydraulic fracturing experiments on highly permeable and on low-permeability rock samples. Experiments were conducted in both sleeve fracture and direct fluid fracture modes using two different injection rates. Consistent with previous studies, our results show that hydraulic fracturing occurred only with low permeation, either due to the intrinsic low permeability or due to the presence of an inner silicon rubber sleeve. In particular, due to the presence of quasi-impermeable inner sleeve or borehole skin in the sleeve fracturing experiment, fracturing occurs, with the breakdown pressure supporting the linear elastic approach considering poroelastic effects, therefore, with low stress drop and consequently low microseismicity. Rock matrix permeability also controls the presence of precursory Acoustic Emission activity, as this is linked to the infiltration of fluids and consequent expansion of the pore space. Finally, permeability is shown to mainly control fracturing speed, because the permeation of fluid into the newly created fracture via the highly permeable rock matrix slows down its full development. The application of these results to the field may help to reduce induced seismicity and to conduct well stimulation in a more efficient way.

Stress due to interfacial slip causing sleeve fracture in shrink-fitted work roll

The rolls are classified into two types; one is a single-solid type, and the other is a shrink-fitted construction type consisting of a sleeve and a shaft. The bimetallic work rolls are widely used in the roughing stands of hot rolling stand mills. Regarding a shrink-fitted construction type, the interfacial slip sometimes appears between the shaft and the shrink-fitted sleeve. This interfacial slip can be regarded as the relative displacement between the sleeve and the shaft. In this paper, the stress due to the interfacial slip is studied because the stress may cause the sleeve fracture. It is found that the stress in the shrink-fitted surface is slightly decreased with increasing number of rotations [Formula: see text]. Therefore, the stress obtained by the simulation at [Formula: see text] can be used to estimate the fatigue strength.

Patella sleeve fracture injury: a case report

Patella sleeve fracture is a rare injury that occurs in children and is characterized by an avulsion of extensive sleeve of cartilage and periosteum with small bony fragments, usually from the inferior pole of the patella. It is important to make this diagnosis promptly and act accordingly, because a delay or misdiagnosis will result in severe permanent disability to the affected child. A case of this injury is presented to create awareness among physicians, especially front-liners within the medical community in Sub-Saharan Africa, where such an injury has been rarely reported in the literature. The presentation, evaluation, management and outcome over a six months period is being presented.

Transosseous Repair of Patellar Sleeve Fractures: A Case Series and Surgical Technique Guide

The purpose of this study is to describe the surgical technique and outcomes of transosseous repair of patellar sleeve fractures in a pediatric cohort. A retrospective review was performed on patients younger than 16 years undergoing transosseous repair of distal patellar sleeve fractures. A chart review was performed on demographics, surgical repair technique, and postoperative care. Primary outcomes included intact extensor mechanism function and range of motion (ROM) at final follow-up. In this study, 20 patients, 17 males and 3 females, with a mean age of 11.7 years were included. ROM was initiated at a median of 27.5 days following surgery. All patients had a healed patellar sleeve fracture and intact extensor function at final follow-up. Final mean knee ROM among the 18 patients with minimum 3-month follow-up was 132 degrees. Thirteen patients (72%) achieved full ROM (≥ 130 degrees) and 5 patients (28%) achieved less than 130 degrees knee flexion. Duration of initial immobilization was found to be the only variable strongly associated with final postoperative ROM. Mean duration of immobilization for patients achieving ≥ 130 degrees was 24 days versus 44 days in those patients achieving < 130 degrees, p = 0.009. All patients who began knee ROM within 21 days of surgery obtained full knee ROM. No patients experienced construct failure or extensor lag. Operative management of displaced patellar sleeve fractures with anatomic transosseous suture repair of the sleeve fracture, brief immobilization no more than 21 days, and initiation range of early ROM results in excellent outcomes.

Neglected Isolated Sleeve Fracture of the Superior Pole of the Patella in a Healthy Adult – A Case Report and Review of Literature

Introduction: Sleeve fracture (SF) represents an unusual type of patellar fracture and has been reported mainly in children or adolescents. Superior pole fracture in adults is a very rare occurrence because the enthesis of the adult patella is more resilient to avulsion injury as compared to an immature pediatric skeleton. Due to the rarity of these fractures in adults and vague radiographic findings, the chances of missing the fracture are very high. Case Report: An 18-year-old boy presented to our outpatient department with a history of fall while trying to jump across a wall 6 months ago. At the time of presentation, the patient mainly complained of loss of active extension of the knee in the sitting position and a palpable gap over the upper part of the patella. After radiographic evaluation, a diagnosis of SF was made. The patient was managed surgically, and thereafter, early rehabilitation was done. After 10 weeks post-surgery, the patient was free from any pain, had a full range of motion, and was able to walk without support. Conclusion: Adults presenting with acute injury to knee with limitation of extension and palpable gap over the superior pole of the patella, a differential diagnosis of SF must be suspected and should be ruled out by clinical examination and relevant investigations. Keywords: Sleeve fracture, patella, superior pole, adult.

Superior pole patellar sleeve fracture after medial patellofemoral ligament reconstruction

A 13-year-old boy sustained a superior pole patellar sleeve fracture after a blunt trauma of the knee. A medial patellofemoral ligament reconstruction had been performed 4 weeks earlier. The patient underwent surgery to reinsert the quadriceps tendon in the superior pole of the patella using two bone suture anchors. One-year postoperative assessment revealed excellent functional outcomes. Sleeve fractures are easily misdiagnosed, and in our case, clinical examination was essential in order to perform the diagnosis.