Primary CaP Research Articles

Genomic cloning of Xenopus TFIIS (TCEA1) and identification of its transcription start site.

We previously cloned the cDNA of the transcription factor TFIIS (SII) from Xenopus laevis and showed that its expression was not constant during Xenopus development. To investigate its regulation, we cloned the genomic DNA of Xenopus TFIIS, focusing on the 5'-promoter region. Here, we present the Xenopus TFIIS genomic sequence (-1730 to +214) and transcription start site (cap site). We define the position of the primary cap site as the adenine located 142 bp upstream from the adenine of the ATG (Met) codon. Another putative start-site region, where 13 transcriptional start sites are clustered within 12 bp, was mapped about 100 bp downstream of the primary cap site. Although a computer search found putative trans-element binding sites proximal to two Xenopus TFIIS transcription start sites, we could not identify typical "TATA" or "CAATT" boxes upstream of the primary cap site, probably owing to TFIIS's character as a "house keeping gene".

Osteoprotegerin and rank ligand expression in prostate cancer

Objectives. To investigate the expression of osteoprotegerin (OPG) and RANK ligand (RANKL) in human prostatic tissues. The factors regulating the increased turnover associated with prostate cancer (CaP) bone metastasis are unknown. OPG and RANKL are recently identified regulators of bone resorption and bone remodeling. Methods. Tissues from 28 patients with CaP and from 4 normal organ donors were analyzed by reverse transcriptase-polymerase chain reaction and immunohistochemistry for the expression of OPG and RANKL. Results. OPG and RANKL messages were detected in both normal and cancerous prostate samples. In the normal prostate, OPG protein was detected in luminal epithelial and stromal cells (5% to 65% and 15% to 70%, respectively) and RANKL immunoreactivity was observed in 15% to 50% of basal epithelial cells, 40% to 90% of luminal epithelial cells, and 70% to 100% of stromal cells. OPG was not detected in 8 of 10 primary CaP specimens; RANKL was heterogeneously expressed in 10 of 11 CaP specimens. The percentage of tumor cells expressing OPG and RANKL was significantly increased in all CaP bone metastases compared with nonosseous metastases or primary CaP. Conclusions. CaP bone metastases were consistently immunoreactive for both OPG and RANKL compared with nonosseous metastases or primary CaP. The presence of these crucial bone resorption regulators in CaP bone metastases suggests a mechanism whereby CaP cells may modulate bone turnover and has profound implications for the establishment and development of CaP bone metastases in advanced disease.

Stromal and Epithelial Expression of Tumor Markers Hyaluronic Acid and HYAL1 Hyaluronidase in Prostate Cancer

Hyaluronic acid (HA), a glycosaminoglycan, regulates cell adhesion and migration. Hyaluronidase (HAase), an endoglycosidase, degrades HA into small angiogenic fragments. Using an enzyme-linked immunosorbent assay-like assay, we found increased HA levels (3-8-fold) in prostate cancer (CaP) tissues when compared with normal (NAP) and benign (BPH) tissues. The majority ( approximately 75-80%) of HA in prostate tissues was found to exist in the free form. Primary CaP fibroblast and epithelial cells secreted 3-8-fold more HA than respective NAP and BPH cultures. Only CaP epithelial cells and established CaP lines secreted HAase and the secretion increased with tumor grade and metastasis. The pH activity profile and optimum (4.2; range 4.0-4.3) of CaP HAase was identical to the HYAL1-type HAase present in human serum and urine. Full-length HYAL1 transcript and splice variants were detected in CaP cells by reverse transcriptase-polymerase chain reaction, cloning, and sequencing. Immunoblotting confirmed secretion of a approximately 60-kDa HYAL1-related protein by CaP cells. Immunohistochemistry showed minimal HA and HYAL1 staining in NAP and BPH tissues. However, a stromal and epithelial pattern of HA and HYAL1 expression was observed in CaP tissues. While high HA staining was observed in tumor-associated stroma, HYAL1 staining in tumor cells increased with tumor grade and metastasis. The gel-filtration column profiles of HA species in NAP, BPH, and CaP tissues were different. While the higher molecular mass and intermediate size HA was found in all tissues, the HA fragments were found only in CaP tissues. In particular, the high-grade CaP tissues, which showed both elevated HA and HYAL1 levels, contained angiogenic HA fragments. The stromal-epithelial HA and HYAL1 expression may promote angiogenesis in CaP and may serve as prognostic markers for CaP.

A small nucleolar guide RNA functions both in 2'-O-ribose methylation and pseudouridylation of the U5 spliceosomal RNA.

In eukaryotes, two distinct classes of small nucleolar RNAs (snoRNAs), namely the fibrillarin-associated box C/D snoRNAs and the Gar1p-associated box H/ACA snoRNAs, direct the site-specific 2'-O-ribose methylation and pseudouridylation of ribosomal RNAs (rRNAs), respectively. We have identified a novel evolutionarily conserved snoRNA, called U85, which possesses the box elements of both classes of snoRNAs and associates with both fibrillarin and Gar1p. In vitro and in vivo pseudouridylation and 2'-O-methylation experiments provide evidence that the U85 snoRNA directs 2'-O-methylation of the C45 and pseudouridylation of the U46 residues in the invariant loop 1 of the human U5 spliceosomal RNA. The U85 is the first example of a snoRNA that directs modification of an RNA polymerase II-transcribed spliceosomal RNA and that functions both in RNA pseudouridylation and 2'-O-methylation.

Clinical Evaluation of Percent Free Prostate–Specific Antigen Using the AxSYM System in the Best Analytical Scenario

Objective: Percent free prostate–specific antigen (PSA) is a promising tool for prostate cancer (CaP) diagnosis. However, its diagnostic performances have not yet been established. The present study was carried out with the aim of evaluating percent free PSA in the most favourable analytical conditions.Materials and Methods: Eighty–eight patients affected by newly diagnosed, untreated, primary CaP, and 169 cases with biopsy–confirmed, untreated, benign prostatic hypertrophy (BPH) were prospectively enrolled. Abbott AxSYM total and free PSA were measured by the same technician using the same instrument and the same reagent batch.Results: Percent free PSA was more effective than total PSA in differential diagnosis between CaP and BPH in every evaluated dose range of total PSA. In cases with total PSA >4 μg/l, percent free PSA could have reduced by about 50% the rate of unnecessary biopsies with a probably still acceptable 93% cancer detection rate. The likelihood of CaP after the determination of percent free PSA was in fact higher than 50% using cut–off points which provide low sensitivity values (i.e. 58% in men aged 50–59 years).Conclusions: Percent free PSA is superior to total PSA in distinguishing primary CaP from BPH in patients with total PSA between 2 and 30 μg/l and in reducing the rate of unnecessary biopsies in men with total PSA higher than 4 μg/l. However, percent free PSA should be cautiously interpreted in decision making in individual patients since post–test probability is relatively low in men aged 50–70 years.

Identification of two distinct regions of allelic imbalance on chromosome 18q in metastatic prostate cancer

Like most cancers, prostate cancer (CaP) is believed to be the result of the accumulation of genetic alterations within cells. Previous studies have implicated numerous chromosomal regions with elevated rates of allelic imbalance (AI), using mostly primary CaPs with an unknown disease outcome. These regions of AI are proposed sites for tumor suppressor genes. One of the regions previously implicated as coding for at least one tumor suppressor gene is the long arm of chromosome 18 (18q). To confirm this observation, as well as to narrow the critical region for this putative tumor suppressor, we analyzed 32 metastatic CaP specimens for AI on chromosome 18q. Thirty-one of these 32 specimens (96.8%) exhibited AI at one or more loci on chromosome 18q. Our analysis using 17 polymorphic markers revealed statistically significant AI on chromosome 18q at 3 markers, D18S35, D18S64 and D18S461. Using these markers as a guide, we have been able to identify 2 distinct minimum regions of AI on 18q. The first region is between the genetic markers D18S1119 and D18S64. The second region lies more distal on the long arm of the chromosome and is between the genetic markers D18S848 and D18S58. To determine if 18q loss is a late event in the progression of CaP, we also examined prostatic intraepithelial neoplasia (PIN) and primary prostate tumors from 17 patients for AI with a subset of 18q markers. We found significantly higher AI in the metastatic samples. Our results are consistent with 18q losses occurring late in CaP progression.

Genetic pattern of prostate cancer progression.

Genetic alterations in primary prostate cancer (CaP) have been extensively studied, yet little is known about the genetic mechanisms underlying progression of primary CaP to metastatic prostate cancer. As a result, it is not possible to distinguish clinically indolent localized disease from potentially life-threatening tumors with high metastatic potential. To address this question, we collected tissue from 34 autopsy-derived metastases, samples rarely analyzed in previous studies. These were compared to a separate set of 17 prostatectomy specimens containing 22 foci of CaP associated with 49 examples of high-grade prostatic intraepithelial neoplasia (PIN), a histological precursor of CaP. We compared the loss of heterozygosity (LOH) profiles of high-grade PIN, primary CaP and metastases by analyzing 33 microsatellite markers previously found to have high frequencies of LOH in primary CaP. These markers were on chromosomes 5q, 6q, 7q, 8p, 9p, 10q, 11p, 13q, 16q, 17, 18q and 21q. In addition, markers on chromosomes 4p, 11q, 14q and 20q with no reported LOH in primary CaP were analyzed to determine the frequency of background LOH. In PIN lesions, the rate of LOH was significant only at D5S806 (20%) and D16S422 (29%). In addition, different PIN lesions within the same prostate gland were genetically diverse, indicating divergent evolution of synchronous neoplastic precursor lesions. LOH frequency was progressively higher in primary CaP and metastatic lesions. In primary CaP, significant losses occurred at the 8p, 10q, 11p, 16q, 17p, 18q and 21q loci (range 17-43%). Distinct patterns of LOH frequencies were observed in primary CaP compared with metastases. Although some loci (D16S422, D17S960, D21S156) showed similar frequencies of LOH in primary CaP and metastatic CaP, most other loci showed up to 7-fold metastasis-related increases. The metastatic samples revealed previously unrecognized prostate cancer LOH at D5S806, D6S262, D9S157, D13S133 and D13S227. These significant stage-specific differences in LOH frequency specify genetic loci that may play key roles in CaP progression and could represent clinically useful biomarkers for CaP aggressiveness.

Percent free prostate-specific antigen in assessing the probability of prostate cancer under optimal analytical conditions

Although general consensus exists that percent free prostate-specific antigen (PSA) is superior to total immunoreactive PSA for prostate cancer (CaP) detection, its diagnostic performance is not yet well established. Analytical problems may account for difficulties in evaluating percent free PSA because the free PSA concentration is substantially lower than that of total PSA. The aim of the present study was to establish the diagnostic performances of the IMMULITE percent free PSA assay from Diagnostics Products Corp. under experimental conditions optimized to minimize analytical variability. Eighty-five patients with untreated primary CaP and 261 with untreated benign prostate hypertrophy (BPH) were prospectively enrolled. The Diagnostics Products IMMULITE total (Third Generation) and free PSA were measured by the same technician, using the same instrument and the same reagent batch. We calculated the post-test probability to express how the likelihood of the diagnosis of CaP changed after the percent free PSA was determined. Areas under the ROC curves of percent free PSA were better than those of total PSA in every evaluated range of total PSA. The percent free PSA could have reduced the rate of unnecessary biopsies by 47% in patients with total PSA >/=4 microg/L with only 3.8% false-negative results. The post-test probability of percent free PSA was, however, <50% in men 50-70 years of age, using cutoff points providing sensitivity from 99% to 80%. Percent free PSA is superior to total PSA in distinguishing primary CaP from BPH in patients with total PSA between 2 and 30 microg/L. In men with low total PSA, the diagnostic performance of the percent free PSA assay may be optimized by controlling methodological variability. The percent free PSA assay is effective in reducing the rate of unnecessary biopsies in men with total PSA >4 microg/L. However, the post-test probability provided by percent free PSA is relatively low in asymptomatic patients 50-70 years of age.

Prostate cancer probability after total PSA and percent free PSA determination.

The percent free PSA value is a promising diagnostic tool for prostate cancer. However, its actual role has not yet been established because of the widely diverging sensitivity and specificity values. This could depend at least in part on analytical difficulties, since the free PSA concentration is much lower than that of total PSA. The present investigation was designed to evaluate the diagnostic performance of the percent free PSA in the most favorable analytical conditions. 81 patients affected by newly diagnosed, untreated primary prostate cancer (CaP) and 239 patients with untreated benign prostatic hyperplasia (BPH) were prospectively enrolled. Hybritech total and free PSA were measured by the same technician using the same reagent batch. The percent free PSA was not significantly associated with age, tumor stage, gland volume, Gleason score, and total PSA, nor was it significantly affected by concomitant prostatic complications either in CaP or BPH. Percent free PSA was more effective than total PSA in the differential diagnosis between CaP and BPH in every evaluated dose range of total PSA. Percent free PSA determination could have reduced the rate of unnecessary biopsies in cases with total PSA > or = 4 ng/mL and > or = 10 ng/mL (avoided biopsies 61% and 63%, respectively). The post-test probability of the disease, which represents the proportion of patients with a positive percent free PSA value who have the disease, was, however, relatively low in younger patients with total PSA within the normal range. The diagnostic performance of the percent free PSA value is enhanced when the methodological variability is reduced, particularly in men with low total PSA. Percent free PSA is superior to total PSA in distinguishing primary CaP from BPH in patients with total PSA between 2 and 30 ng/mL. The percent free PSA value is effective in reducing the rate of unnecessary biopsies in men with total PSA higher than 4 or 10 ng/mL. However, due to its relatively low post-test probability, the percent free PSA value should be interpreted with caution in the decision-making related to individual patients and should be used in association with clinical and instrumental evaluation of the patient.

Identification of two estrogen receptor transcripts with novel 5' exons isolated from a MCF7 cDNA library.

Two novel transcripts of human estrogen receptor (ER) have been identified that differ in the 5' untranslated sequence. It has previously been determined that an alternate ER transcript is generated from transcription initiated upstream of the main ER cap site (P1), and utilizes a splice acceptor site at +163. Here we report the isolation of 21 ER clones from a MCF7 cDNA library. Eleven of these clones correspond to transcripts that initiate at the P1 cap site, whereas the remaining 10 clones are derived from two previously unidentified ER transcripts (designated E and H) that both utilize the +163 splice acceptor site. A panel of breast and endometrial carcinoma cell lines were screened by reverse transcriptase-polymerase chain reaction (RT-PCR) for expression of the E and H transcripts. It was found that all ER-positive cell lines expressed both of the novel transcripts. In addition, 10 primary human breast cancers were analyzed, of which six expressed the E transcript and five abundantly expressed the H transcript. These data indicate that expression of ER in human breast cancers can be dependent upon an alternate promoter at least 20 kb upstream of the primary cap site for ER.

The Linde structure, Denmark and example of a CO 2-depository with a secondary chalk cap rock

The Danish Linde Structure is being investigated with respect to be used as a depository of CO 2. The structure has been drilled with a comprehensive coring and logging program thus making the structure suitable to use as a model structure. The reservoir rock is sand, while the primary cap rock is claystone, with chalk as a secondary cap rock. In the case of the Linde reservoir, when carbonic acid may react with the calcite secondary cap rock, or with carbonates cementing the reservoir sandstone, the gas/brine/rock chemistry is also extremely important. Dissolution and weakening of the cap rock may put an effective stop to the utilization of an otherwise interesting formation for CO 2 storage.

Phosphorus transformations in a toposequence of lithosols and cambisols from semi-arid northeastern brazil

Concepts of phosphorus transformations in soils and landscapes have largely been developed in temperate regions on moderate slopes. Little is known about the P dynamics and availability in semi-arid tropical soils where rainfall extremes cause limited but periodically intensive leaching and erosion. We therefore studied the different forms of inorganic P (Pi) and organic P (Po) as related to mineralogy and landscape position in semi-arid northeastern Brazil. Samples were collected from a catena of Lithosols at upper, and Cambisols at mid and lower slopes. All soils were derived from syenite which had a high total P content near 5500 mg kg −1. Phosphaterich particles were identified by X-ray microprobe as fluor-apatite. The apatite contents of the A horizons were reduced in the weathering sequence from Lithosols to the older Cambisols, while the total P contents diminished to between 1200 and 2300 mg kg −. The lower-slope soils had also lost two thirds of the Ca, Mg and Fe contents from sand and silt fractions. Chemicals fractionation of P showed the lowest Ca-P contents in the C horizons of the Cambisols, indicating a maximum transformation of primary Ca-P in these lowermost horizons. Deposition of partly weathered materials from upper slopes explained some of the differences in the Ca-P contents between R and C horizons and the overlying solum at the mid and lower slope. Similarly, some Lithosols showed an exceptionally high Ca-P contents suggesting that these soils have been replenished with unweathered material from rock outcrops above. Microprobe analysis revealed P-rich silt particles containing Fe, Al and Ca, which may be explained by the impregnation of primary Ca-P with Fe-oxyhydroxides. This absorption of Fe by mineral particles would represent a short-cut in the transformations of primary P to secondary, resistant P forms. The observation of Fe-oxyhydroxide coatings in feldspars from saprolite indicates that such transformations did occur and may have general importance where primary and highly weathered minerals are intimately mixed through erosion, limited leaching and high weathering intensities typical of semi-arid tropical environments. Only 5% of the total P was found in organic forms, mostly in stable forms of low availability with little contribution to P fertility.

The catabolite activator protein stabilizes its binding site in the E. coli lactose promoter.

The effect of catabolite activator protein, CAP, on the thermal stability of DNA was examined. Site specific binding was studied with a 62 bp DNA restriction fragment containing the primary CAP site of the E. coli lactose (lac) promoter. A 144 bp DNA containing the lac promoter region and a 234 bp DNA from the pBR322 plasmid provided other DNA sites. Thermal denaturation of protein-DNA complexes was carried out in a low ionic strength solvent with 40% dimethyl sulfoxide, DMSO. In this solvent free DNA denatured below the denaturation temperature of CAP. The temperature stability of CAP for site specific binding was monitored using an acrylamide gel electrophoresis assay. Results show that both specific and non-specific CAP binding stabilize duplex DNA. Site specific binding to the 62 bp DNA produced a 13.3 degrees C increase in the transition under conditions where non-specific binding stabilized this DNA by 2-3 degrees C.

Texaco''s Expanded Bonnie Glen Solution Gas Processing And NGL Fractionation Facilities

Introduction When Texaco Canada Resources Ltd. opened the $40 million addition to its Bonnie Glen gas processing facHities in June 1982, the three-plant complex located 80 km southwest of Edmonton, became one of Canada's largest natural gas liquids producers. The new Bonnie Glen Solution Plant No.2 can handle 1.4 million cubic metres of gas a day, including a 2780 cubic metre a day fractionation train. The new solution gas processing plant was completed on time and on budget under an engineering, procurement and construction turnkey contract. The Oilfields Texaco's Bonnie Glen complex serves two of Canada's most prolific oilfields, Wizard Lake and Bonnie Glen, discovered within a year of each other in the early 1950s. The Wizard Lake oilfield, about 11 km north of the Bonnie Glen Gas Plant, has an original oil-in-place of 61.2 million cubic metres and has been under pressure maintenance since 1969. The Wizard Lake Miscible Flood is one of the largest and most successful enhanced recovery projects of its type in the world. The project increased the field's recoverable oil by 11 million cubic metres to an estimated 84% of the original oil-in-place. Over the years, some 4.4 million cubic metres of LPG solvent has been injected into its miscible slug. The field, 100% owned by Texaco, can produce up to 8700 cubic metres of oil per day. The Bonnie Glen find differed from Wizard Lake because it had an original primary gas cap overlying the 119 million cubic metres of oil-in-place. This pool, 74% Texaco owned, is not under pressure maintenance. However, ultimate recovery is still expected to be 71% of the original oil-in-place with a production capability of 1300 cubic metres a day. In 1975, the gas cap was unitized and a cycling scheme was brought on-line which has successfully minimized retrograde losses and improved ultimate pool recovery by 4.3 million cubic metres. The Processing Complex The Bonnie Glen gas processing complex today includes three facilities: two solution gas plants, Nos. 1 and 2, each with a 1.4 million cubic-metre-a-day capacity and a cycle plant which has a 3.9 million cubic-metre-a-day capacity to extract natural gas liquids as part of the gas cap cycling project (Fig. 1). The original Bonnie Glen Solution Plant No. 1 came into operation in 1954 with the capacity to handle 790 000 cubic metres of gas a day. It was one of the first gas plants built in Alberta, installed at that time for conservation purposes. Plant No.1 had five integral compressors, a mine sweetening and ambient temperature lean oil absorption systems and a fractionation facility. By 1969, the plant's rated capacity was increased to 1.4 million cubic metres a day through a series of improvements which included the addition of compression, a propane refrigerated gas fractionator downstream of the lean oil absorber and a second depropanizer. Then as now, Plant No.1 extracted more NGL than it could fractionate. The excess raw NGL formed one of the solvent streams injected in the Wizard Lake Miscible Flood.

Improved Reservoir CharacterizationA Key to Future Reservoir Management for the West Seminole San Andres Unit

A comprehensive reservoir study using a black-oil simulation model showedthat control of vertical movement of oil into the gas cap under waterfloodoperations was the key to maximizing oil recovery from this west TexasSan Andres reservoir. Recovery of an additional 4 MMSTB of oil isexpected as a result of a reservoir management plan which includes a46-well infill drilling program. Introduction Improved reservoir description is becomingrecognized as an essential requirement for effectivereservoir management. This is particularly important for the extremely heterogeneous, geologicallycomplex San Andres carbonate reservoirs of westTexas. The West Seminole field in west centralGaines County, TX, (Fig. 1) produces from the SanAndres formation at an average depth ofapproximately 5,100 ft. Fig. 2a shows the generalstructural configuration of the reservoir; it consistsof a large main dome with a smaller dome structureto the east. A large primary gas cap, shownschematically in Fig. 2b, covers most of the fieldarea. A summary of basic reservoir and fluid data ispresented in Table 1. Throughout the field's producing life, there hasbeen a question about the extent of verticalcommunication within the reservoir, particularly betweenthe oil zone and the overlying gas cap. This questionbecame a critical operating consideration when apattern waterflood was proposed in the early 1970's.An extensive reservoir study was undertaken topredict the future production performance of thefield under waterflood operations. The overall objective of this study was to developthe most profitable and effective reservoir managementprogram for the West Seminole San Andres Unit. Thefollowing specific objectives and procedures weredeveloped for the work.Use all available geologic and engineering datato develop a detailed and accurate reservoirdescription for this field.Incorporate the reservoir descriptioninformation into a black-oil computer simulationmodel. Use the simulator to verify and further refine the reservoir description by history matching thepressure and production data.Use the history-matched simulation model toproject future reservoir performance under currentwaterflood operations.Evaluate various alternative operating plans andrecommend the most effective reservoir managementprogram for the unit. JPT P. 2009＾

Scab Cementing-An Economical Workover Technique For Effective Production Control

Abstract The Main Gatchell zone of the Coalinga Nose field, Fresno County, Calif., is one of the major oil pools in the state. One very significant phase of over-all operations in this field is scab cementing. Scab cementing used in the Coalinga Nose field as a method of well workover, establishes cement bonds between the perforated liner and the formation, separating a single long productive interval into several short intervals. Cup-type tubing packers and choke nipples are set opposite these cement bonds to allow selective production of oil, gas and water using the control obtained from bottom-hole chokes. The cemented perforated sections are called "scabs".Detailed descriptions of the various phases of scab cementing are given, as well as an analysis of the costs involved. Nearly all of the wells recompleted by scab cementing in the Coalinga Nose field are still flowing. Some or all of the techniques used in scab cementing for production control have been applied to other workover operations where a cement bond is needed between perforated or blank pipe and the formation. Successful application of scab cementing in other areas would depend on a careful examination of reservoir conditions, producing mechanisms and methods of lift. Where conditions are favorable for its use, scab cementing is an economical and effective workover technique that allows selective production control through designed tubing strings. Introduction The Main Gatchell zone of the Coalinga Nose field, Fresno County, Calif., is one of the major oil pools in the state. Discovered in 1938, it has produced over 300-million bbl of 31 degrees API oil primarily by a gravity-drainage mechanism. More than 94 per cent of the productive acreage was included when the Coalinga Nose Unit was formed on March 1, 1950.The Main Gatchell zone is a stratigraphic trap situated on a plunging anticline. The reservoir is a thick, massive quartzose sand of Eocene age. The air permeability averages about 750 md in the up-structure portion of the reservoir which is very nearly isotropic. Dips range from 100 to 300 at the sand and underlying shale contact, depending upon regional location on the structure. Drill depth to the top of the Main Gatchell zone averages about 7,500 ft. There was no primary gas cap in the Main Gatchell zone. Early in the productive life as the reservoir pressure decreased, gas accumulated at the top of the structure and expanded into the up-structure producing wells as a well-defined secondary gas cap, indicating that an effective gravity segregation of oil and gas was taking place. The attendant increases in gas-oil ratios of up-structure wells were controlled in many instances by decreasing the oil rates. When this was no longer effective (or when the ratios became excessive) the wells were shut in or, if feasible, deepened. Fig. 1 shows the area affected by the growth of the secondary gas cap over the years. History of Cementing Workovers It was recognized early that remedial operations would be necessary to control gas production from the encroaching secondary gas cap. The current scab-cementing method of production control, with minor variations, was initiated in 1950 and is the only method described in detail in this paper. Scab cementing is used in the Coalinga Nose field as a method of well workover, or repair. This establishes cement bonds between the perforated liner and the formation, separating a single long productive interval into several short intervals. Cup-type tubing packers and choke nipples are set opposite these cement bonds to allow selective production of oil, gas and water using the control obtained from bottom-hole chokes. The cemented perforated sections are called "scabs". JPT P. 349^

Extensions of the Muskat Depletion Performance Equation

Published in Petroleum Transactions, AIME, Volume 213, 1958, pages 285–291. Abstract Muskat's depletion performance equation is here derived considering the expansion behavior of the reservoir hydrocarbon system and a simple fractional-flow equation. This method of derivation leads logically to the two extensions that follow. The first of these is concerned with gravity segregation in a depletion-drive reservoir. The second is concerned with including an empirically determined term for water influx in the performance equation. The more general equation for gravity segregation when there is a primary gas cap and empirically-determined water influx is stated for completeness. These equations have been found useful in reservoir performance calculations in Eastern Venezuela. A discussion on the methods of solving these equations follows, and considers firstly the effect of taking finite intervals in the numerical integration, and secondly, methods of incorporating the time functions involved in segregation in with the expansion behavior. The paper concludes with a brief general discussion on further extensions to the depletion performance equation. Introduction The two fundamental sources of energy by which oil is produced from a reservoir result from pressure depletion inside the boundaries of the reservoir and fluid encroachment across the boundaries of the reservoir. The wells in either case form low pressure outlets through which oil and gas may be produced by the expansive force of the reservoir fluids and associated encroaching fluids. When the reservoir pressure is higher than the bubble-point pressure of the oil, so that there is no free gas in the reservoir, these expansive forces are the only ones available for the production of oil. However, when the reservoir pressure is less than the bubble-point pressure of the oil, free gas is vaporized as the pressure falls. With both oil and free-gas phases present, the additional forces of gravity and capillarity may operate on the gas-oil system, as they have previously operated on the oil-interstitial water system. Gravity tends to segregate the free gas from the oil due to their density difference. Capillarity opposes and eventually balances gravity as the more extreme free gas and oil saturations are reached, preventing the independent movement of free gas until it is above a certain saturation, and the independent movement of oil when it is below a certain saturation.

The Performance of the Ten Section Oil Field

Introduction The Ten Section oil field is located in the San Joaquin Valley in KernCounty, California, about 12 miles southwest of Bakersfield in Township 30South, Ranges 25 and 26 East. The accumulation is in a low relief anticlinaldome and has a productive area of approximately 2,200 acres. Discovered in 1936as a result of seismic work, it was the first field on the floor of the Valleyto obtain production. It had a small primary gas cap, and since its inceptionhas been produced by depletion with controlled withdrawal from the gas cap tominimize blowthrough. Structure and Stratigraphy The Ten Section structure is an elongated anticlinal dome with flank dips ofonly about 7 degrees. A map of the field, now fully developed, and a compositelog are shown in Figs. 1 and 2. Contours shown on the map are on the top of thefirst zone, or Marker XA as indicated on the composite log. As shown, the field has a productive closure of only some 350'Feet, and thereapparently is no faulting in the reservoir. The productive measures in Ten Section are of Upper Miocene age and are knownas the Stevens sand. They contain thin, irregular shale or siltstone streakswhich vary considerably in stratigraphic position and thickness and apparentlyare rather discontinuous. As a result, individual sands and shales cannot becorrelated over any appreciable area, which makes it difficult to subdivide thesand body into separate zones which are distinct throughout the field. However, there are two fairly persistent siltstone bodies that at the time ofdevelopment were considered to divide the productive measures into threegeneral zones. The first, or uppermost zone is productive over the entire field and has anaverage thickness of 180'Feet, of which some 65 per cent is sand. It had aprimary gas cap in the crestal area with an areal extent of 930 acres. Thesecond zone has a productive area somewhat smaller than the first zone, but itdid not have any original gas cap. It has an average thickness of about 360feet, of which 55 per cent is sand. The third zone has a very limited arealextent and a maximum productive thickness of 100'Feet, of which 80 per cent issand. Recently, a deeper oil accumulation, termed the "53" sand, wasdiscovered, but it is not discussed in this analysis. In the first and secondzones the water table was at 7,980'Feet subsea, while in the third zone it wasat 8,080'Feet subsea. T.P. 2643

Some Theoretical Aspects of Well Drainage and Economic Ultimate Recovery

Abstract A method for incorporating well drawdown effect into reservoir calculations ispresented in detail, together with examples of its use for widely divergentconditions that could be normally encountered in oil reservoir sands. Tentativeconclusions as to the effect such factors as permeability, producing interval, well spacing, or well damage caused by completion or repair practice could haveupon economic ultimate recovery are reached. It is carefully pointed out thatthe conclusions reached are subject to limitations indicated in the text, andplaced upon all calculations made in the paper. Introduction Papers have been presented I-a in which theoretical depletion histories forreservoirs under equilibrium conditions and no appreciable well-bore drawdownpressure are determined. However, except for a limited number of cases, appreciable drawdown pressures in a well bore exist, and pressure andsaturation gradients consequently vary throughout a reservoir. This paper is an attempt to incorporate well-pressure drawdown into reservoirhistory, and to analyze certain factors, such as those involving recovery, wellspacing, and productivity index, from the standpoint of permeability anddrainage radius. By incorporation? of drawdown into reservoir history, it isbelieved that theoretical considerations will more closely approximate actualreservoir behavior experienced in an oil field. For purposes of simplification, a solution gas-drive typefield, without primary gas cap, has been selected. Basic Data and Assumptions Details of equilibrium saturation conditions for no drawdown production forvarious pressures in a reservoir are determinable by methods described byseveral authors permitting the construction of a curve of oil saturation vs.pressure for any selected combination of initial interstitial water andhydrocarbon saturation (Fig I). This curve is then a description of equilibriumsaturation conditions at any given pressure in a reservoir. Developing the above, details of saturation and flow permeability may thus bedetermined for any increment or portion of a well drainage area or reservoir, In this manner the effect of pressure differential (draw down) may beincorporated into reservoir and well drainage considerations. It is pointed out that this method thus makes use of no-drawdown equilibriumproduction data, superimposing a drawdown effect upon them. It also assumesthat net flow conditions in any considered increment of reservoir are notmaterially altered by the entrance of fluids from other increments into them, but approach equilibrium for the existing pressure and saturation (i.e., eachincrement behaves in more or less independent fashion, dependent largely uponthe equilibrium considerations mentioned above). T.P. 2201

Karyosphere formation and synapsis in the beetle, phanaeus

AbstractThe parasynaptic union of chromosomes associated with the formation of a karyosphere is demonstrated in the spermatocytes of Phanaeus.The twelve V‐shaped leptotene threads are polarized with their apices embedded in one plasmosome‐like body, their distal ends in another (primary and secondary caps, respectively), and undergo a conjugation of the parasynaptic type. The distal ends of the chromosomes are freed from their attachment in the secondary cap. The six pachytene loops retain their polarized configuration.The basichromatin of the pachytene chromosomes appears ultimately to be withdrawn to form the karyosphere comprising six chromatic bodies within an oxychromatic «plasmosome,» the latter probably derived from the primary cap. The two caps are believed to arise from the chromosomes. The primary cap apparently becomes incorporated again in the chromosomes; the secondary cap, together with linin remnants of the pachytene chromosomes, disintegrates in the nucleus as residual chromatin.In the dissolution of the karyosphere six ring‐shaped tetrads emerge arranged in a temporarily connected chain, giving under certain conditions, the misleading impression of twelve components arranged end to end. The entire content of the karyosphere appears to be employed in the formation of the chromosomes; no visible plasmosome remains.