Permeability development within and around the cement, placed in the casing-hole annulus in oil and gas wells, is a frequently encountered worldwide problem that might lead to various adverse economic and, possibly, catastrophic consequences. The resultant loss of hydrocarbon production and, sometimes, the wells constitutes the major part of the adverse economic impact. The loss of wells, in turn, might lead to severe environmental pollution and most importantly the loss of lives. Sustained casing pressure (SCP,) described as the pressure buildup due to flow through the permeable cement matrix or the micro annulus developed around the cement, had been experienced by about sixty percent of the wells producing oil and/or gas in the Gulf of Mexico, according to the literature. Although various methods are used to prevent the problem, there is no widely accepted universal method by the industry. Currently, the problem is attempted to be mitigated using distinct methods applied either during the cementing operations or after the problem is detected. The present study is an experimental investigation for the prevention of permeability development within and around the set cement at ambient conditions. A natural magnesium complex with carbonate, coded ARI, is used the first time ever as a cement additive to achieve desired prevention. Gas permeability measurements are conducted on the samples of cements of 19 different compositions, at the end of the successive curing periods up to 28 days. ARI containing cement samples are found to develope an impermeable matrix to gas flow and to exhibit no shrinkage in volume during setting. The performance of ARI as a cement additive is also investigated in the presence of other commonly used cement additives, e.g. friction reducer and fluid loss controlling agents.

Polymer augmented alkaline flooding (PAAF) is a relatively new EOR process, and its first version has been defined as injecting an alkaline slug chased by a polymer slug. During the early 1980's the second version of PAAF was introduced, being composed of a single slug of alkaline and polymer blended together, followed by a polymer slug. A series of corefloods was conducted with alkaline solution, polymer solution, and a blend solution of alkaline and polymer in linear and radial Berea sandstone cores for studying the mechanisms of the second-version PAAF process. Sodium hydroxide was used as the alkaline agent, and the polymer was 30-percent hydrolyzed polyacrylamide. The efficiency of the second-version PAAF was compared with that of both alkaline flooding and polymer flooding alone. Results showed that the synergistic effect of the second-version PAAF provides better efficiency than either alkaline or polymer alone for enhancing oil recovery. This chemical system of alkaline and polymer blended together yielded more oil recovery with increasing blend slug size. Also, a phenomenon never before reported was observed. It is a visible residual oil saturation ring next to the region cleaned of oil adjacent to the injection sand face, and it was observed in both linear and radial cores after the application of the second version PAAF process. The size of this oil ring is similar to the size of the blend slug of alkaline and polymer.

Discussion - No abstract available.

This study is conducted to prevent the accidental petroleum product release from some onshore storage tanks into seas, in Turkey. The seawater, used to displace the liquid petroleum products from tanker ships into the onshore storage tanks, accumulates under the petroleum product in the storage tank. The field personnel, operating the gravity-controlled seawater discharge manually, may occasionally miss the discharge time and close the discharge valve too late. Hence, the petroleum product, chasing seawater in the discharge line, is accidentally released to the sea. Thus, estimating the seawater discharge time accurately is of great value for eliminating the potential coastal and offshore environmental damage, preventing the petroleum product loss, and for efficient use of personnel time. The flow behavior is modeled mathematically for the accurate estimation of total seawater discharge time. A semi-steady-state flow model is developed by the integration of an unsteady-state mass balance and a steady-state energy balance. The effect of conical geometry of such tank bottoms on flow behavior is also taken into account. The differential equations of the model are solved by both analytical and numerical integration techniques. Excellent agreement of both results is obtained and compared with the field data. Introduction In the transfer of a LHP (Liquid Hydrocarbon Product) from the tankership into the onshore storage tank, LHP is pumped through the port pipeline, which would be filled with seawater, initially. Here LHP refers to various petroleum products, such as fuel oil, diesel oil, gasoil, gasoline, etc. As the LHP is pumped from the tankership, the seawater in the pipeline is first displaced into the onshore storage tank. When all LHP is pumped out of the tankership, the port pipeline would still be filled with LHP. The pipeline should be kept free of LHP, becausethe LHP in the pipeline should be put into the storage tank for sales, andthe pipeline may need to be allocated for the transfer of another type of LHP into another onshore storage tank. Thus, the tankership pumps seawater to displace the LHP out of the pipeline into the storage tank, and pipeline is left as filled with seawater. Finally, the initially displaced seawater and a small part of the displacing seawater enter the storage tank and reside under the LHP column. Once the transfer operation is completed, seawater in the onshore storage tank is discharged back into the sea. A widely used application of seawater discharge from such storage tanks in Turkey is a manual operation. The discharge valve of the storage tank is opened and seawater is let flow out through the discharge line, until the chasing LHP appears in the separator by the shoreline, then the discharge valve is shut manually. The schematic in Figure 1 illustrates this operation. The level of seawater in the tank and, in turn, the discharge time may vary depending on the diameter and height of the storage tank, the volume of transferred LHP in the tank, and the conditions of the transfer operation. Thus, the exact time of seawater discharge is generally unknown to the personnel in charge, who has to wait and observe the LHP appearance at the separator and then shut the discharge valve. Problems in Current Seawater Discharge Practice The problems encountered in the current seawater discharge practice mentioned here exhibit some technical difficulties and some adverse consequences. Inefficient Use of Personnel Time. A seawater discharge operation is completed in a time frame of at least one hour or more. Having one person idle and waiting for the appearance of LHP at the separator in that time frame is a very inefficient use of personnel time. Inefficient Use of Personnel Time. A seawater discharge operation is completed in a time frame of at least one hour or more. Having one person idle and waiting for the appearance of LHP at the separator in that time frame is a very inefficient use of personnel time.

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