Airway neutrophilia is a prominent feature of chronic obstructive pulmonary disease. As cigarette smoke (CS) and epidermal growth factor (EGF) both cause release of interleukin-8 (IL-8) from epithelial cells in vitro, we investigated whether autocrine ligands for the EGF receptor (EGFR) are involved in this proinflammatory response to CS. NCI-H292 or primary bronchial epithelial cells were cultured with or without cigarette smoke extract (CSE) or EGF for 6-48 h. We then tested culture supernatants for lactate dehydrogenase activity to assess cell viability, and for IL-8 and EGFR ligands by ELISA; quantitative RT-PCR was used to measure IL-8 and EGFR ligand mRNA. EGF and low concentrations of CSE both promoted cell survival and caused enhanced transcription and release of IL-8. Similarly, levels of mRNA encoding transforming growth factor alpha (TGF-alpha), heparin-binding EGF-like growth factor, and amphiregulin (AR) were increased, as was shedding of TGF-alpha and AR protein into the culture medium. With the exception of AR gene transcription, the CS-induced responses were blocked by the EGFR-selective kinase inhibitor AG1478. Furthermore, ~ 45% of CS-induced IL-8 release was inhibited by a neutralising anti-EGFR. Our data indicate that secretion of IL-8 in response to CSE is dependent on EGFR activation and that autocrine production of TGF-alpha makes a substantial contribution to this response.

We described a nondestructive method to estimate the maximum and minimum horizontal stresses and formation nonlinear elastic constants using sonic data from a vertical wellbore. This method for the estimation of horizontal stress magnitudes consists of using radial profiles of the three shear moduli obtained from the Stoneley and cross-dipole sonic data in a vertical wellbore. These shear moduli change as a function of formation stresses, which in turn change as a function of the radial position away from the wellbore. Two difference equations were constructed from the three far-field shear moduli and the other two were constructed from differences in the shear moduli at radial positions with different stresses in the presence of near-wellbore stress concentrations. Outputs from this inversion algorithm included the maximum and minimum horizontal stress magnitudes, and two rock nonlinear constants referred to a local hydrostatically loaded reference state. The underlying acoustoelastic theory behind this inversion algorithm assumes that differences in the three shear moduli are caused by differences in the formation principal stresses. Additionally, the orientation of the maximum horizontal stress direction was identified from the fast-shear azimuth in the presence of a dipole dispersion crossover. Hence, the principal horizontal stress state was fully determined. Good agreement was obtained between the predicted minimum horizontal stress magnitude and that measured from an extended leak-off test in a vertical offshore wellbore in Malaysia. One of the nonlinear constants was obtained from differences between compressional velocity at two depths caused by differences in the overburden stress and the maximum and minimum horizontal stresses. Estimates were obtained for the stress coefficients of the compressional, fast-shear, and slow-shear velocities referred to a local reference state. These stress coefficients of velocities helped in the interpretation of observed time-lapse changes in seismic traveltimes caused by fluid saturation and reservoir stress changes.

The purpose of this paper is to provide the oil industry completion engineers with a workable method for selecting the appropriate fluid loss control systems for their completions. Fluid loss has long been recognized as a major concern when determining completion costs and assessing well management. For this reason, much research has been dedicated to investigating various methods and equipment to address the scenarios from which fluid loss results. Numerous papers have been written over the years on fluid loss control during well completion and workover. Many of these papers describe a specific method that has been used to address the problem, and a number of innovative devices and fluids have been developed. Most of these devices or systems have been addressed individually in the literature or as comparisons between products that are similar in design and function. Little has been provided on evaluating the merits of a variety of systems in an effort to provide a means of selecting an appropriate solution on a well-by-well or situation basis. This paper provides an in-depth discussion on the benefits, limitations, methods of operation, and possible applications for each of the methods and equipment currently in use.

This paper was prepared for presentation at the SPE Annual Technical Conference and Exhibition held in Houston, Texas 3–6 October 1999.

Introduction This paper will focus on recent advances in hydraulic fracturing technology with emphasis on North Sea applications. Five generalized applications that will benefit most from advances in technology have been identified. Because North Sea oil and gas field development requires the use of platform facilities for wellhead and processing equipment, deviated and horizontal wells are often used to effectively drain the reservoirs. Many of these wells require fracture stimulation. The success rate of such wells has increased significantly in recent years as a result of the following:Researchers better understand how fractures initiate and grow.Pre-treatment diagnostic techniques have improved substantially.Engineers better understand how completion design affects well performance. With improved understanding of post-frac well performance, engineers can evaluate the feasibility of developing a reservoir through fractured, horizontal wells. A significant number of the new fields developed in the North Sea will be marginal fields. As a result, the most advanced technologies must be used to ensure economic uccess, even though the funds available for pre-frac planning will be limited. Advances in diagnostic injection tests, real-time treatment analysis, and on-site redesign capabilities help ensure that hydraulic fracturing can be successfully applied in such marginal fields. Several high-pressure, high-temperature (HPHT) fields are currently being developed in the North Sea. Although HPHT fracturing has not yet been attempted in the North Sea, it has been successfully applied in other parts of the world. In addition to a review of the advances in HPHT technology that would apply to North Sea applications, this paper will identify improvements necessary before these techniques are applied in the North Sea. One of the most significant occurrences in fracture advancement is the expansion of fracturing techniques to reservoirs that traditionally were not considered fracturing candidates. Historically, hydraulic fracturing was considered an engineering tool for improving well productivity from tight, therwise non-commercial reservoirs. Now, however, hydraulic fracturing is being used more frequently (1) in high-permeability reservoirs to improve the overall profitability f the project, and (2) as an alternative to traditional sand control applications in soft, weakly consolidated reservoirs. The effect of hydraulic fracturing operations on the North Sea environment must be recognized. The advances in fluid design and post-treatment flowback procedures that minimize these effects are discussed. Fracturing Deviated and Horizontal Wells North Sea oil and gas field development requires the use of platform facilities for wellhead and processing equipment. Deviated and horizontal wells have a natural application in these conditions where wellheads are located close together yet reserves are located in a radial pattern around the installation. Many North Sea reservoirs require stimulation to maximize production rates and economic returns. As a result, propped hydraulic fracture treatments have been successfully used for both oil and gas production in horizontal and highly deviated wells in several sectors of the North Sea. In theDanish sector alone, over 300 propped hydraulic fracture stimulation treatments have been performed to date. The North Sea has led the industry in this technology.