Cementing Method Enhances Well Killing KILLING and CEMENTING DRILLING with CASING Has Been Used in South Texas to Reduce Costs

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IADC/SPE DRILLING CONFERENCE: CEMENTING & ZONAL ISOLATION Cementing method enhances well killing KILLING AND CEMENTING DRILLING WITH CASING has been used in South Texas to reduce costs. Underbalanced drilling seems to have the potential to eliminate an intermedi- ate casing string. By drilling underbalanced, it would be possible to drill with a mud weight low enough to prevent loss of circulation in the shallow weak zones while dealing with the gas from the pay zones below. Drilling with casing eliminates the necessity of trips. However, once TD was reached, it would be necessary to balance the well to allow cementing of the production casing string. The challenge was to develop a way to kill the well so that the cement could be placed and allowed to set while at the same time not breaking down and losing circulation into the weak upper zones. This had to be done by having different equivalent circulating densities and equivalent mud weights up and down the 98896: In tests measuring the mechanical parameters of five cement formulations after exposure to hole throughout the circulating and a temperature of 645 degrees Fahrenheit, the temperature conditions to which the cement was cementing operation. This paper exposed was found to have a significant impact on the mechanical parameters. The mechanical describes the development of the required methodology and its successful parameters of systems exposed to 645 degrees varied significantly from systems exposed to an ambi- field application. ent temperature of 77 degrees. Simultaneous Dynamic Killing and Cementing of a Live Well (IADC/SPE Peroyea, T Aguilar, ExxonMobil; DT cement would be in the range of 50 to 150 98440) PA Solano, Halliburton; R Strick- Mueller, D Doherty, BJ Services. psi. Is this assumption correct? ler, ConocoPhilips; DD Moore, Signa This paper characterizes the early state Engineering Corp. CEMENT DESIGNS physical properties and mechanical behavior of accelerated Type I, Class A, DEEP GAS WELL CEMENTING Pressure events that occur after surface G, and H cement designs during the 12 casing cementation impose stress on the hours after placement. This paper discusses the risk analysis cement sheath. If pressure testing takes Characterization of the Early Time and development plan that led to the place early in cement curing, the tangen- Mechanical Behavior of Well Cements selection of a liquid cement premix for tial stress imposed may exceed the ten- Employed in Surface Casing Opera- large-volume jobs. The paper covers the sile strength of the cement, thereby tions (IADC/SPE 98632) DT Mueller, RN design requirements of the jobs and inducing cement sheath failure. Eid, BJ Services. addresses the risks associated with the In most wellbore pressure scenarios, the available options. Information is provid- cement sheath fails in tension. The pro- ed on risks associated with boat and portionality between the compressive ULTRA-HIGH TEMPERATURES barge stability, draft limits at available strength and the tensile strength of set The ability of a cement sheath to remain bulk facilities, deck load limits and logis- cement is generally assumed to be a 10:1 tics of alternate designs. intact when exposed to changing well- ratio. In surface casing applications, the bore stresses is highly dependent on the The paper further covers the equipment time at which induced pressure events parameters of Young’s Modulus, Pois- requirements and mixing needs and occur may be as low as 8 to 12 hours son’s Ratio and tensile strength of the compares the selected option to that of a after the cementing operation. cement and the surrounding rock. conventional cement job. In this time frame, the cement will have a Wells subjected to Cyclic Steam Stimula- Deep Gas Well Cementation: A Review compressive strength ranging from that tion (CSS) for heavy oil recovery undergo of Risks and Design Basis for Use of a required for the commencement of drilling extreme temperature changes. During Liquid Cement Premix for Large Off- operations (500 psi) to upwards of 1,500 CSS, wellbore temperatures can fluctu- shore Cementing Operations psi. Accordingly, conventional wisdom ate between 77 deg F and 645 deg F. (IADC/SPE 98970) G Benge, JB Darby, M would hold that the tensile strength of the

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IADC/SPE DRILLING CONFERENCE: CEMENTING & ZONAL ISOLATION Various Finite Element Analysis models require input of cement mechanical parameters. But no mechanical parameters are made after long-term exposure of the cement to the ultra-high temperatures encountered in CSS wells. This paper presents a test methodology for measuring the mechanical parameters of five cement formulations after exposure to a temperature of 645 deg F. Effects of Long Term Exposure to Ultrahigh Temperature on the Mechan- ical Parameters of Cement (IADC/SPE 98896) D Stiles, ExxonMobil.

EXTREME STRESSES The deep Bossier formations of the East Texas Hilltop Field encounter low per- meability gas bearing formations at over 15,000 psi and 400 deg F. Wellbore temperature variations occurring between 98891: A dedicated injector well was chosen as an application for stress modeling and a novel new stimulation and production operations sealant. Stress modeling indicated that as wellbore temperature decreased from bottomhole static are extreme. Two of the first three wells completed in this area failed via casing to injection temperature, and bottomhole pressure cycled between static and dynamic conditions, collapse. conventional cement would fail in tension and create a microannulus. In view of these challenges, Analysis confirmed that the extreme the team in charge of cementing the well decided to redesign the cement program incorporating stresses being applied to these wells ren- stress analysis calculations and mechanical properties testing to provide a sealant material that dered the previous casings and cement sheaths as underdesigned. Detailed ther- would resist failure due to excessive wellbore stresses. mal and mechanical modeling of all wellbore operations resulted in redesigned This article presents the results of a Rivereau, A Audibert-Hayet, X Lon- casings. comprehensive study on the degradation gaygue, Inst Francais du Petrole. High-strength, corrosion-resistant cas- of cement in simulating the interaction of the set cement with injected supercritical ings and specialty cement designs were CEMENTING DISPOSAL WELL successfully used. All of the wells have CO2 under downhole conditions. withstood stimulations at treating pres- Mitigation Strategies for the Risk of This paper will discuss the design, exe- sures exceeding 14,000 psi, production CO2 Migration Through Wellbores cution and evaluation of a dedicated drawdowns of over 13,000 psi, and tem- (IADC/SPE 98924) V Barlet-Gouedard, injector well in the Grane field in the Nor- perature changes estimated at over 300 TS Ramakrishnan, Schlumberger; G wegian North Sea for an application for degrees F. Rimmele, B Goffe, ENS/CNRS. stress modeling and a new sealant. Finite Element Analysis Couples Cas- Stress modeling indicated that conven- ing and Cement Designs for HT/HP CEMENT DURABILITY tional cement would fail in tension. The Wells in East Texas (IADC/SPE 98869) team redesigned the cement program JF Heathman, Halliburton; F Beck, Gas- It’s estimated that 40 percent of the incorporating stress analysis calcula- tar Exploration Ltd. world’s remaining gas reserves contain a tions and mechanical properties testing CO2 content higher than 2 percent to provide a sealant material that would and/or a H2S content higher than 100 resist failure due to excessive wellbore PREVENTING CO2 MIGRATION ppm. Therefore, special attention has to stresses. The chosen sealant material A leaking wellbore annulus can be a be paid to the design of well materials. incorporated flexible and expanding pathway for CO2 migration into This paper addresses the problem of materials within an optimized particle unplanned zones. durability of oilwell cement in different size distribution blend. With the lack of industry standard prac- hydrogen sulphide environments. The well has been logged with sonic and tices dealing with wellbore isolation for In this paper, we present the methodolo- ultrasonic tools and has indicated an the time scale of geological storage, a gy implemented under HP/HT conditions excellent bonding response. methodology to mitigate the associated for aging tests of materials in H2S-con- Cementing of an Offshore Disposal risks is required. This requirement led to taining fluids and results obtained on Well Using a Novel Sealant That With- the need and development of a laborato- cement-based materials. stands Pressure and Temperature ry qualification of resistant cements and Durability of Oilwell Cement Formu- Cycles (IADC/SPE 98891) CR Johnson, E the long-term modeling of cement sheet lations Aged in H2S Containing Fluids Therond, Schlumberger; C Scheie, I integrity. (IADC/SPE 99105) E Lecolier, A Hydro; R Pedersen, Hydro.

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